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Too Much Synthroid (Levothyroxine) Symptoms

Synthroid (Levothyroxine) is a synthetic form of T4 (thyroxine), a hormone secreted by the follicular cells of the thyroid gland.  Individuals with insufficient levels of thyroxine (T4) exhibit symptoms of hypothyroidism such as: depression, lethargy, malaise, and sleepiness.  Regular administration of synthroid (levothyroxine) is thought to reverse symptoms of hypothyroidism and normalize all neurophysiological processes impaired by low thyroxine (T4).

When initiating treatment, certain patients may run the risk of taking too much synthroid.  In a majority of cases, individuals that take too much synthroid do so unintentionally.  It is common for patients to misinterpret dosing instructions given by a medical professional and/or pharmacist and mistakenly ingest larger than instructed doses.

In other cases, a doctor may inadvertently prescribe too high of a synthroid dosage for a particular patient.  Since synthroid has a narrow therapeutic index (NTI) for dosing, even slightly too much of the synthetic hormone may provoke a tailspin of unwanted symptoms, most of which resemble hyperthyroidism (or excess thyroid hormone).  If you are taking synthroid and suspect that you may have ingested an excessive amount, it is important to beware of severe synthroid side effects and adverse reactions.

Too Much Synthroid (Levothyroxine) Symptoms

Below is a list of possible symptoms that you may experience if you took too much synthroid (levothyroxine).  Understand that the number and severity of your symptoms will likely be contingent upon how much more synthroid you took than was necessary.  For example, if you were prescribed 100 mcg per day, yet took 300 mcg – you’ll likely exhibit more noticeable effects from too much synthroid compared to someone who was prescribed 25 mcg and took 50 mcg; the contrast is more significant in the first example.

Since synthroid is a synthetic version of thyroxine (T4) that serves as a non-bioidentical replacement, excessive amounts may lead to hyperthyroidism-like symptoms.  Common symptoms experienced from those who take too much synthroid include: anxiety, diarrhea, rapid heartbeat, sweating, and increased body temperature.  Should you experience any of these symptoms while taking synthroid, medical attention is warranted.

  • Anxiety: There is a relationship between excessive thyroid hormone and neuropsychiatric anxiety. If after taking synthroid you feel insanely anxious, jittery, and nervous – it could be a result of an abnormally high dosage.  Some users have reported that taking too much synthroid leads to so much anxiety that they cannot sleep, think clearly, or interact socially with others.  Additionally, anxiety resulting from excess levothyroxine may provoke panic attacks or unpredictable feelings of panic and fear.
  • Bone density decrease: There is evidence to suggest that too much synthroid replacement can accelerate bone loss, which in turn may increase likelihood of fractures. Decreased bone density is most likely to occur among those that have taken too much synthroid over a prolonged duration.  Administration of a single supratherapeutic synthroid dosage is unlikely to prompt significant bone loss.  Decreased bone density may be most noticeable among older adults and elderly synthroid users, but may occur in all ages if an abnormally high dosage is repeatedly administered.
  • Chest pain: If you’re experiencing chest pain from synthroid treatment, it is recommended to immediately seek medical evaluation. Chest pain may be a sign of an adverse cardiac response to the medication.  Since high doses of synthroid can affect heart rhythms and function, it is important to rule out serious complications associated with treatment.  Usually chest pain is most common among those that ingested significantly more synthroid than necessary.  Chest pain may also be interrelated to the physiological anxiety and tension associated with high doses.
  • Diarrhea: It is known that excessive levothyroxine (synthroid) can cause severe gastrointestinal distress and stomach aches. Many people lose weight from high doses simply because they cannot hold down food.  Too much synthroid is thought to expedite the movement of food through the digestive tract, leading to frequent bowel movements or diarrhea.  Diarrhea can occur even at standard doses, but is more likely to occur (and be more severe) among high-dose synthroid users.
  • Difficulty concentrating: Ingesting excess synthroid (levothyroxine) is likely to cause difficulties with concentration and focus. You may feel so anxious, jittery, and wired with disconcerting physical symptoms – that it becomes nearly impossible to stay focused on any cognitively demanding task.  To ensure that your concentrative abilities return, you’ll want to get your dosage adjusted and/or refrain from using unnecessarily large synthroid doses.
  • Fever: Thyroid hormones play an important role in thermoregulation and when modified to extremes (as in the case of taking too much synthroid), body temperature can fluctuate. In the event that you took too much synthroid, you’re likely to feel excessively hot and with a fever.  If the amount ingested wasn’t considerably more than your daily requirements, the fever may be low-grade.  However, in the event of an overdose (or ingesting significantly more than necessary), the fever is likely to be high and possibly fatal.
  • Hair loss: Individuals taking too much synthroid are more likely to experience hair loss than those taking proper dosages. While hair loss can occur as a side effect during the first few months of treatment, most users notice that hair loss subsides as the body adapts to the daily synthroid administration.  If you’ve been regularly ingesting too much synthetic thyroxine (synthroid), hair loss may be more substantial and may never subside until the dosage is reduced.
  • Headaches: Another common symptom associated with ingesting too much synthroid is headaches. While headaches are a normal side effect of the medication (even at standard doses), excessively high doses of synthroid trigger severe headaches (e.g. migraines).  If you feel a throbbing, incessant headache that won’t subside, it could be a sign that you’ve administered too much synthroid.
  • High blood pressure: Synthroid treatment may trigger hypertension, especially when too high of a dose is ingested. Blood pressure spikes and/or irregularities may be most prominent among those who have a history of hypertension, but can occur among any user that has unintentionally (or intentionally) administered too much synthroid.  It is important to realize that if ignored, hypertension (from too much synthroid) could lead to complications such as: blood vessel damage, heart attack, and/or stroke.
  • Hot flashes: Taking too much synthroid can cause hot flashes or sudden waves of feverish heat, usually localized in the facial region. The hot flashes may be accompanied by profuse sweating, and in some cases, an actual fever.  Even slightly too much synthroid may be enough to trigger more hot flashes than usual.  That said, hot flashes are also considered a normal side effect of synthroid, so don’t automatically suspect that you took too much if you only experience a hot flash.
  • Insomnia: Individuals that regularly ingest supratherapeutic doses of synthroid are likely to exhibit insomnia or inability to fall asleep (or stay asleep). Those that inadvertently ingest too much synthroid will likely notice that no matter how hard they try to relax and drift off to sleep – they cannot overcome the insomnia.  While mild insomnia may not be too problematic, sometimes it leads to a full night of sleeplessness – which can have numerous deleterious health implications.
  • Irritability: The combination of anxiety, jitteriness, and nerves can lead some individuals that took too much synthroid to feel irritable. You may find yourself angry at every “little thing” and as if you’re ready to snap at friends and/or family over minor disputes.  It is important to recognize that if you weren’t irritable prior to taking synthroid, it’s probably induced by the medication.  Though this is a side effect experienced by many individuals taking standard doses, it is especially common among those who took too much.
  • Menstrual irregularities: Female users that take too much synthroid are likely to experience menstrual irregularities. Some women report that after starting synthroid, their periods are whacky and completely unpredictable – this is a normal side effect.  However, chronically taking too high of a synthroid dosage may cause abnormally light periods and/or even missed periods.  Assuming you’ve been taking unnecessarily high synthroid doses for awhile, time between periods is likely to be prolonged.
  • Muscle weakness: It’s no surprise that individuals who take too much synthroid could end up with serious muscle weakness. High concentrations of levothyroxine can accelerate bone density loss and possibly even muscle loss via increases in BMR.  The reduction in bone density and muscle tissue may be responsible for causing muscle weakness.  Muscle weakness may be most noticeable among older adults and/or elderly synthroid patients.
  • Nervousness: Nervousness can occur as a standard synthroid side effect – even when taken at the proper dose. That said, if you end up taking too much synthroid, nervousness is very likely to occur – leading you to feel uncomfortable and riddled with anxiety.  The nervousness may be accompanied by a racing heart, sweating, thoughts of panic, and muscle tension.  Once your dosage is readjusted to a proper level, nervousness should lessen in severity.
  • Profuse sweating: Taking slightly more synthroid than necessary can increase likelihood of sweating. On the other hand, taking substantially more synthroid than necessary is nearly a surefire guarantee to sweat profusely.  Although sweating is a standard side effect reported at normal doses, profuse and/or excessive unremitting sweats are most likely to be a result of excess levothyroxine intake.  Too much synthroid increases body temperature, causes hot flashes, and alters blood flow – ultimately causing some users to sweat uncontrollably.
  • Rapid or irregular heartbeat: A very common symptom of taking too much synthroid is rapid or irregular heartbeat. Most individuals are consciously aware of changes in heartbeat and/or rhythms as provoked by synthroid.  Ingesting too much levothyroxine can cause atrial fibrillation or even heart failure (especially among those with preexisting heart disease).  The greater the quantity of synthroid ingested over the optimal amount (for you as an individual), the more likely you are to experience heartbeat irregularities.  If you took too much synthroid and are experiencing heartbeat irregularities, immediate medical attention is essential.
  • Shortness of breath: If you took too high of a synthroid dosage, you may feel as if you’re constantly gasping for air or having a tough time breathing. Shortness of breath is common among those who take too much synthroid.  While shortness of breath could just be a result of increased anxiety from too much synthroid, it could also be a sign of a more serious adverse reaction (e.g. heart attack).  For this reason, it is necessary to seek medical evaluation if you have this symptom after taking too large of a synthroid dose.
  • Sleeplessness: If you took more synthroid than prescribed (or too much for your particular condition), you may be unable to sleep at night. While insomnia may occur among those that took slightly more synthroid than necessary, outright sleeplessness is common among individuals that ingested considerably larger doses than medically required.  Someone that overdoses on synthroid will have a difficult time getting any sleep – and if they do get sleep, the quality will be poor.
  • Temperature sensitivity: You may find that warm temperatures are intolerable after taking too much synthroid. This is because excess levothyroxine increases blood flow to the skin, making you feel warmer than usual.  It also generates more body heat than necessary as a result of changes in metabolism.  As a result, you sweat more, feel feverish, and may be unable to tolerate a warm or hot environment.  Upon correction of your synthroid dosing, you may feel as if you can actually tolerate a warm environment.
  • Tremors: Abnormally high doses of synthroid can cause some individuals to shake uncontrollably, particularly in the hands. If you’ve noticed tremors in your hands, legs, facial muscles, etc. – it could be that you’re overstimulated with too much levothyroxine.  A doctor may need to readjust your dosage if the tremors continue throughout your treatment.
  • Vomiting: A telltale symptom that you may have taken too much synthroid is vomiting. Prior to vomiting you may feel extremely nauseous and unable to maintain an appetite.  Although not everyone who takes too much synthroid will vomit, if you’re vomiting, it is likely a sign from your body that too much has been ingested and/or you’re unable to tolerate the drug.  If you constantly vomit and feel like you have the flu, seek medical attention immediately.
  • Weight loss: When initially beginning synthroid treatment, it is common for users to end up losing some weight; this is due to a reversal of hypothyroidism-induced BMR slowing. If you’ve been taking too much synthroid, not only will you likely feel like an anxious, sleepless maniac, but you’ll probably shed more body weight than expected.  Some of this weight loss will be a result of GI changes (e.g. diarrhea), some may be due to decreased bone density and/or muscle loss, and most will be from an abnormally increased BMR (basal metabolic rate).  (Read: Synthroid and Weight Loss).

Note: Not all people that take too much synthroid will experience every last symptom listed above.  Symptoms of taking excess synthroid may be subject to interindividual variation.  If you believe you took too much synthroid and are experiencing any symptoms, consulting a medical professional is advised.

Taking Too Much Synthroid: Interindivdiual Variation in Dosing

Individuals undergoing treatment for hypothyroidism with synthroid are prescribed dosages aimed to optimize TSH (thyroid stimulating hormone) levels.  Excessively high TSH levels signifies that an individual is likely not getting enough synthroid.  Since the severity of hypothyroidism is subject to individual variation and synthroid dosages necessitate patient-specific optimization, “too much synthroid” for one user may be a normal dose for another.

A person with severe hypothyroidism who weighs 200 lbs may take around 1.7 mcg/kg/day – for a daily total dosage of ~154.22 mcg.  Should the individual end up taking 175 mcg per day, he/she may exhibit subtle symptoms associated with too much synthroid.  On the other hand, someone who weighs 140 lbs and is taking 1 mcg/kg/day for subclinical hypothyroidism, a total daily dosage may be just 63.5 mcg.

If the individual instructed to take 63.5 mcg of synthroid ends up taking 175 mcg per day, more severe symptoms are likely to emerge because the recommended dosage will have been surpassed by a significant amount.  The lesser the extent to which an optimally calibrated dosage is surpassed, the less severe and/or numerous the symptoms of too much synthroid are likely to be.  The greater the dosage over the optimal amount of synthroid needed for optimal function, the greater the symptomatic severity associated with the “overdose.”

Reasons patients may take too much synthroid

There are several hypothetical reasons as why a patient may end up taking too much synthroid.  While taking too much is certainly not the “norm,” it could be a result of: misinterpreted dosing instructions, improper dosage (as prescribed by a doctor), or intentionally taking more than usual (either to improve symptoms or to inflict self-harm).  Most individuals that take too much synthroid do so unintentionally and/or unknowingly.

  1. Misinterpretation of dosing instructions: Some synthroid users may misinterpret dosing instructions as given by their doctor. While dosing instructions are generally confirmed with a pharmacist prior to administration of synthroid, some individuals are more absent-minded than others. It is possible to consider that a simple slip-up on the end of the patient may lead to ingestion of a dose that is larger than necessary.
  2. Improperly calibrated dose: Although most doctors attempt to prescribe patients with a minimal effective dose of synthroid, not all patients respond to low doses when beginning treatment. For this reason, a doctor may slightly overshoot the necessary dosing needs for a particular patient. Regular administration of an improperly calibrated dose can provoke symptoms of too much synthroid.
  3. Faster symptomatic relief: In rare cases, a patient may try to play “doctor” on themselves by making personal adjustments to their dosing. A patient may experiment with higher-than-necessary dosages in attempt to reverse hypothyroidism symptoms as soon as possible. Although the patient may believe that he/she will attain faster relief by taking a greater dosage than prescribed, this may lead to adverse effects and complications associated with too much levothyroxine.
  4. Intentional overdose: Another small percentage of patients may feel anxious, depressed, and possibly suicidal while taking synthroid. These individuals often have an underlying comorbid neuropsychiatric diagnosis (e.g. major depressive disorder, bipolar disorder, etc.). It is possible that the patient may attempt to inflict self-harm by overdosing on synthroid (levothyroxine).  In the event of an overdose, very severe symptoms are likely to arise – requiring immediate medical attention.

What should you do if you took too much synthroid?

If you know (or suspect) that you may have ingested too much synthroid, seeking emergency medical attention is necessary.  Complications arising from a synthroid overdose could be fatal if they aren’t addressed in a timely manner.  Thereafter, you should take steps to minimize the likelihood of future dosing errors by reviewing and confirming dosing instructions with your doctor.

  1. Seek medical attention: Since taking too much synthroid could prove to be fatal, it is necessary to seek medical assistance as soon as possible after your dosing. If you know that you overdosed and/or intentionally took too much, call emergency medical services and/or get yourself to a hospital. In rare cases, individuals may die of hyperthermia and/or cardiac arrest associated with elevated levothyroxine concentrations.
  2. Refrain from synthroid usage: If you know you took too much synthroid, your doctor may instruct you to refrain from synthroid usage for a day or two after your abnormally high dose. Don’t immediately stop taking synthroid without medical instruction, but be cognizant that in the event of an overdose, ingestion of additional synthroid may exacerbate adverse effects. Work with your doctor to determine when it is safe to resume normative synthroid administration.
  3. Optimize future dosing: Sometimes you may need to work with your doctor to review your current dosing regimen. This may involve blood testing for TSH, FT4, and FT3 to determine how you are affected by the synthroid. Assuming concentrations of TSH aren’t within a normal range (e.g. are too low), you may need to reduce your synthroid dose.  The goal should be to take a minimal effective dose of synthroid – or just enough to optimize TSH levels without inducing side effects from too much levothyroxine.

Have you ever taken too much synthroid (levothyroxine)?

If you’ve ever taken too much synthroid, leave a comment detailing your experience.  Share the symptoms you experienced, how much synthroid you took, and whether taking too much was accidental or intentional.  If the dosing error was unintentional, did it result from misinterpreting in the dosing instructions as given by a doctor or your pharmacist?

For those who intentionally took a higher-than-prescribed dose of synthroid, share your motive for doing so.  Document the most prominent symptoms you experienced as a result of ingesting excess levothyroxine.  How long did it take you to get over these symptoms and did you discuss them with a medical professional?

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{ 47 comments… add one }
  • Paul March 5, 2018, 5:21 pm

    Found out I had thyroid cancer at the end of 2016; got a full thyroidectomy at MD Anderson; my endocrinologist started me on 200mcg of Synthroid; at first, I wasn’t quite sure what was going on. I found that I have less energy and not motivated to really take on exercising or being active. I am generally a fairly active person; enjoy outdoor sports, tennis, swimming, biking, etc., but now just more tired than before.

    I also did tend to get sweaty at times and not even doing anything, being tired during my awake hours, I can doze off (30-90mins) just sitting on a couch even after a full-night’s rest of 7-8hrs. I wasn’t like that before the thyroidectomy; I’m about 5-8, 220lbs; my weight stayed fairly constant before and after the surgery.

    I don’t have any issues sleeping before & after starting Synthroid. Then I went to my primary-care doctor for my annual/full check-up in mid-2017; found a few things that either are just part of being 46 years old or coincidentally from the higher dosage of Synthroid, I don’t know. I found myself in the pre-diabetic range (5.7%-6.4%) with my A1C result which was not the case before.

    I was diagnosed with Low-T, consistently under the standard range of 264-916ng/dL (measured 5 times between Apr 2017-Feb 2018) which my doctor informs me that I should check my bone density next especially if I don’t want to start any Testosterone therapy. My T4, free remains above the standard range of 1.77; averaging at 2.05 ng/dL measured 4 times in the same period (Apr 2017-Feb 2018).

    I’m also on blood pressure medication, Losartan, which I had just started at around the same time I’d found out I had thyroid cancer. I had my Endocrinologist lower my dosage from 200mcg to 175mcg in May 2017, so I was on 200mcg for 6 months. I think I did feel a bit better, not as tired all the time. Since the change, I’ve tried to plow through my day staying active as much as I can, I still find myself a bit ‘off’, tired at times and just a general lack of motivation unless I just overcome by staying active and getting even more tired.

    I think my weight is part of the problem too, so I have started a goal to try and lose 5-10% this year. My next endocrinologist visit isn’t until August, but I will ask her to lower it again, probably to 150mcg and see if that helps further.

  • Rachel March 3, 2018, 11:21 pm

    I once a slightly higher than usual dose of levothyroxine at my doctor’s advice because I hadn’t been able to take it for several days due to a stomach bug and was experiencing some pretty bad symptoms of hypothyroidism. I am NEVER gonna do that again. I have had panic attacks from Bipolar Disorder, but, they were nothing compared to the one I had after taking the extra levothyroxine.

    About 30 minutes after I took it, I started feeling a little nervous and thought it was about the appointment I was heading off to. Normally, I love car rides, but, this time, I completely lost my mind. When I got in the car with her to go to my appointment, I suddenly felt really claustrophobic, the movements of the vehicle were more intense than usual, I kept yelling at my mom to stop and let me out.

    She finally did after I almost passed out while we were going down a hill, and, being a nurse, she realized I was having a reaction to the surge in thyroid hormones, so, she told me to take my beta blocker, which, thankfully, stopped the reaction, and I was able to continue with the rest of my day, avoiding exertion. Next time, I will just resume my normal dose.

  • Nisha February 21, 2018, 9:38 pm

    I was advised to take 100mcg in pregnancy, before that I was taking 88mcg. After delivery, I was prescribed to take 88 mcg again. It caused me itching and anxiety. Itching is getting worse. Today I got my blood work results out and doctor has prescribed 50mcg now. Hoping I will be better in a week or two.

  • Dennis Rued February 12, 2018, 2:00 pm

    Hi. I’ve been hypo for 18 years now. My levels are rarely the same. I have the unique benefit/punishment of a former girlfriend trying to kill me by swapping my Synthroid for her seroquel. Lots of fun. The hospital ended up giving me 100,000 x my normal rate to bring me around. It’s left its mark.

    I regularly would increase the amount of Synthroid I would take because I knew what happened in me when I didn’t have enough. The alternative had to be better. I don’t have many of the symptoms of over medicating. However, the ones I do have are difficult to cope with.

    I’ve been vomiting and attributing it to pain that I cope with. Also, the person saying they slept 90 minutes A day, resonated with me. People think I don’t remember sleeping more than the 18 minutes I say I get on occasion.

    Those are rare, but there are plenty of sleepless nights. This article has changed the way I will proceed in the future in ways other than allowing someone else to set up my medications. Thank you

  • Sarah February 12, 2018, 2:53 am

    I started taking levothyroxine over a decade ago and was very stable on 50 mcg a day. However, at the beginning of 2017, I discovered that I had an issue with excess dietary copper. I worked to balance copper and zinc in my diet and later also realized I needed to balance iron and vitamin E. I came off all my supplements except for 400 IU of vitamin D a day (which I balance with vitamin A and other nutrients through diet), a complete omega supplement, and a probiotic.

    Several months after working through all these dietary issues, I started feeling terrible. I stopped my medication the day after my doctor did some thyroid blood work and noticed I felt a lot better. I later ordered lab tests to check things to make sure my results had normalized.

    When I had that blood work done, nearly two months after I stopped taking my medication, my TSH was elevated, over 6.5, compared to around 5.1 when it was tested the last day I was on medication. I decided to try going back on my medication by taking only half a tablet a day. About two and a half weeks later, I begin having the same symptoms as before when I decided to stop.

    While it may seem that my dietary changes are making me not need thyroid replacement hormone, the test results seem to suggest otherwise. I thought they might be due to high reverse T3 caused by too much T4, but I’m just not sure at this point. The only thing I can think of to try right now until I go back to my doctor next month is to take the half tablet every other day.

    My hemoglobin, MCV, MCH, and MCHC were all just slightly lower than normal on both tests (same day as thyroid tests were done), but I’ve had these issues at other times over the years and have never had problems with my thyroid medication at those times. In fact, this time, I wonder if the thyroid medication is causing the low numbers. I’m just not sure what’s going on.

    • Sarah February 14, 2018, 3:41 am

      I thought of something today that might explain my numbers. Perhaps the 6.5 could have actually been a part of a downward trend from a previously higher number. Over time after stopping my medication, perhaps my TSH got even higher than the 5.1 and then started coming down. Perhaps it will be even lower when I see my doctor next month. I can certainly hope!

  • Carol February 6, 2018, 7:11 pm

    When I was first prescribed Synthroid following a thyroidectomy in 2014, I inadvertently took 2 doses within 30 minutes and immediately experienced rapid heart rate and anxiety (compounded by fear upon realizing what I had done!). I knew that calcium interferes with absorption of Synthroid, so I downed a quart of yogurt and drank a lot of water. The negative side effects were gone in about an hour, and I never did that again!

  • Bert January 21, 2018, 4:26 pm

    Hi, I have been taking synthroid 175 mcg for approx 10 years after iodine drink and all was great, this past 6 months I have suffered from many of the symptoms of the list above, I am now hyper. I missed a few days of taking synthroid as per my physician. I have now been prescribed 150 and retest in 30-60 days.

    I could tell something was wrong as my mind would not stop thinking, headaches and diarrhea, also muscle ache and exercise didn’t seem to do anything for my muscles, trouble thinking and after many years I have been told my blood sugar is high, but I have not changed my daily routine. Doctor suggests to get my thyroid medication back to normal and retest everything, hope this helps.

  • Farmacyherb January 9, 2018, 1:12 pm

    Thanks information helped a lot! I’m experiencing all the above symptoms, doctor prescribed me 300 mcg of synthroid. I’m over-medicated… yikes.

  • Irene January 2, 2018, 12:13 am

    Great posts everyone…they are really so helpful. I have been overdosed twice, on by my doc who wrote the wrong prescription and I was being underdosed. I had the typical hypo symptoms which improved after a new doctor caught the error. Then, after years on the same dose, I went “crazy” as my family calls it, one summer and upon testing, the endo cut my dosage from 125 mcg to 75 mcg.

    About 6 years ago, I began having insomnia and extreme body pain. I was diagnosed with fibromyalgia but by then I had stopped seeing my endo due to scheduling difficulties and was relying on a gp. After 6 years of severe “fibro” pain, I discussed my tsh level with my gp. It had gone down from .75, to .52 and then .26 over a 3 year period.

    I had been to see my gp and rheumatologist repeatedly over the years as I dealt with severe pain and insomnia. I had been having muscle spasms, headaches, dry skin, hair falling out, etc. My gp finally agreed to cut my synthroid to 50 MCG and my symptoms stopped within a week. I have been pain free for 2 months.

    There were times where I couldn’t stand to have clothing touch my skin, hip pain, shoulder pain, and even feet throbbed in pain all night. Sleeping was difficult with ambien, tramadol er, occasionally t3. I am pretty tough having been through surgeries on my knees, shoulders, cervical fusion, lumbar fusion, etc., but the lack of a good, restorative sleep was horrible. I was supposed to start a new med, gabapentin, to see if it would help with the fibro, and I am so glad I didn’t.

    I even stopped my hrt and had no hot flashes. Now after having 2 steroid injections, 4 weeks apart in my knee, I am back to having horrible hot flashes. The last injection was a month ago so I am not sure if it was the steroid injections or my thyroid again. The hot flashes are common for me with steroids but not for more than 1 week. I hope to get it straightened out soon before my knee replacement this May.

  • Gail May 31, 2017, 5:03 pm

    I’ve been taking 400 mcg everyday for the past year. Way too high! This amount was prescribed by my GP and I had to follow up with an Endo. He is repeat testing my thyroid every 8 weeks as he lowers the dosage little by little. I feel like death.

    Every bone in my body aches, I get severe leg cramps every night and wake up in a pool of water due to sweating. Sometimes I wish the Endo would start on the lower end of scale of meds and work his way up. I surely feel the anxiety as well!

  • Marlene March 9, 2017, 2:31 am

    I was alternating one day 88 mcg, next day 100 mcg for about 2 years with no trouble. Then I started having some palpitations and so was tested … my TSH was 1.2, when normally I was around a 1.5. Since I wasn’t feeling quite right the doctor suggested I just take 88 mcg and stop the 100. Did that for about 4 or 5 months and felt good.

    But then I started getting anxiety. It became worse over the period of a month or two after which time I also started having terrible problems concentrating, developed frequent loose bowels movements, had an increased heart rate and started losing weight. I was surprised – these were symptoms of serious hyperthyroidism, but I had just REDUCED my meds earlier that year!

    I was tested again and TSH was 1.9 , a number that usually produces no symptoms for me. So I thought my symptoms were being caused by something else. I was so edgy and anxious that I seriously felt like I was developing a mental illness… it was HORRIBLE. Finally went to an alternative doctor who suggested I cut my 88 mcg pills in half for week and see what happens.

    I didn’t think my meds were the problem since my TSH was a very middle of the road 1.9, but I took his advice and I swear, within 3 days of lowering the dose my symptoms started to subside. I then saw my Endo and we tried a 50 dose for awhile, but then my TSH shot up to 17. After a year and a half of trial and error, I settled on 75 mcg 5 days a week and 88 mcg 2 days a week.

    Have been doing that for awhile now and I feel great. So at 88 daily, I felt like a lunatic, but the slightly lower dose of 75 with 2x a week at 88 brought me back to feeling normal. My new “ideal” for my TSH is about a 2.5 to 3.5. (It used to be about 1.5 – 2.4). Anything lower and I feel like an crazed, anxious loon.

    My doctor told me that sometimes after women enter menopause, synthroid tolerance and TSH “ideals” can change. Anyway, as bad as hypo feels, I can tell you that hyper is much, much much worse! Go by how you feel, not by the numbers!

  • Dennis Drews,Sr. February 28, 2017, 1:12 pm

    Primary doctor increased my levothyroxine from 50 mcg to 75 mcg. After another blood draw, 2 months later, she increased it to 150 mcg. Within a week I was back in A-Fib. My Cardio doctor said I should have called him before taking the increased dose. She knew my medical history. Cardio doctor lowered dose to 100 mcg. I waited almost a month before having the procedure hoping it would correct itself. WRONG!! Had another cardioversion, Nov. 30, ’16. I have been in rhythm since. Primary doctor said she was “sorry”, but also stated she wasn’t a Cardio doctor. I will be changing primary doctor.

    • Jackie March 27, 2017, 7:10 pm

      Dennis I would suggest an endocrinologist. They will coordinate with your primary and your cardio. Both of the non endo docs prescribe by the numbers. A good endo looks at a lot of factors and will look at t3 and t4. Please get a good endo. Your cardio may be closer than a primary, but you still should have been referred to a specialist for endocrinology.

  • Maxdefl February 26, 2017, 5:56 pm

    I am 40 now. I had thyroid cancer in 2013. I was put on 150 mcg Synthroid after that. I am a big guy (fat, not tall) at almost 6 ft and 250 lbs. Two months later, I find out I am diabetic. Fast forward another 6 months. Thyroid cancer is back. Remainder of thyroid was removed in late 2014. Iodine ablation in December 2014.

    262 mcg for almost 2 years, with tsh suppressed to keep cancer at bay. Now on 237 mcg after TSH was less than 0.01, 6 months ago. I really don’t know which is worse, the anxiety, leg sweats, moodiness and irritability from the heavy doses of synthroid, or an increase in cancer risk. My personality has almost completely changed over the last two years. Scary really.

  • Ginny February 8, 2017, 4:51 am

    I have been taking 75 mcg, Doc told me my TSH was low and increased me to 88mcg. I have had heart palpitations, anxiety, increased heart rate, sleepless nights and hot flashes. I have been on the new dose for 2 weeks.

    Thinking about decreasing my meds. I did feel out of balance, so I agreed to the change in the dosage, but now I feel even worse. It has been six weeks since my last blood draw…is it to soon to be retested? If I am high now…would it show up after 2 weeks on the new dosage?

    • Jackie March 27, 2017, 7:21 pm

      There are some initial reactions to a new dose or even a new manufacturer. Contact your endo and request a follow up.

  • Cheryl January 22, 2017, 8:23 pm

    I have been hypothyroid for over 12 years, maybe longer. I started on 50mcg and had major tachy, anxiety, sweats. Took a cardiologist to stop the Meds and I was on a beta blocker. I have had med changes over the past 12 years. Always get the same symptoms just out of the blue, then continue until I stop Meds.

    Sometimes my TSH is normal sometimes not. I have found the labs are not always indicative of symptoms. Listen to your body. I’m having it again, stopped my Meds felt better, started again and symptoms returned. I am a mess, just moved, started a new job. Ughhhh.

  • MK January 9, 2017, 1:21 am

    My brother has been taking 50 mcg Levothyroxine and due to blood tests and was increased in the beginning of Nov. to 75 mcg. He experienced sleeping issues, anxiety, depression, unclear thinking, then eventually after about 5 weeks, he had insomnia (about 2 hours of sleep a night). Now, after he can’t take it any more and little help from his primary (PA’s and nurses), we decided it was the Levothyroxine that was too strong and needs to go back to 50mcg.

    It’s been two days on 50mcg. How long do you feel it will be before he’s able to sleep 5 or 6 hours again? I have read that after a week or so 50% is out of your system then about another week for another 25%, etc. I really need too know about when the sleeping aspect of the negative side effect will subside.

    (No sleeping prescription is working either!) He’s really breaking down. Could use advice. Will kidney detox help progress ridding his system of side effects quicker? Anything at all to help sleep??

  • Kris December 27, 2016, 1:22 am

    I had radioactive thyroid ablation 15 years ago due to Grave’s. It took a couple of years to get the right dosage of synthroid and I always used name brand synthroid. My thyroid levels have been normal for at least 10 years, then starting March 2016 I had heart palpitations, couldn’t sleep, night sweats, anxiety – I reported this to my doc and my labs showed hyperthyroidism, we didn’t change meds but waited and re-did labs 3 months later.

    I was hypothyroid that time, re-tested in June and was on the low end of normal, re-tested in September and was hyper. This time we changed to generic synthroid and lowered it to 112 mcg from 125. I am having heart palpitations, but am tired all the time, cold, and depressed.

    I have lost weight and am down to 108 pounds. Has anyone else had their labs jump all over the place in a year after many years of remaining stable? My doctor doesn’t have any answers for me when I ask why this could happen. I am curious to see what my next lab draw shows…

    • V January 21, 2017, 8:10 am

      I had my thyroid removed because of a goiter six years ago. This past summer the endocrinologist raised my dosage to 150. This was about time that I was experiencing medical issues, including continued perimenopase, so I attributed the anxiety and shortness of breath to worry. I ended up having emergency gallbladder surgery which increased my anxiety exponentially.

      My primary care physician tried many anti anxiety drugs to no avail. The made the insomnia worse. At one point, the ER department said my levels were fine after a gallbladder attack. I had my levels done for the endocrinologist and she called and said my levels were much too high, I had to stop taking for three days and begin at a much lower dose if 112.

      In three months, I will be tested again, knowing that I will probably have to increase to 125. My symptoms were off the chart. I have never had symptoms of hyperthyroidism before so I was unprepared for all these crazy and frightening side effects. My endo believes that perimenopase/menopause attributed to the rise of my levels since I am completely dependent on medication.

      I will be more diligent in checking my levels between doctor appointments when I feel something isn’t right. Hopefully I will start feeling better sooner than later.

    • Karlina January 31, 2017, 5:09 am

      Exact same scenario here! Also was reduced after 10 yrs from 125 mcg to 112, but after 12 weeks I have GAINED weight back that took me a long time and effort to lose! My nurse changed my dosage after just one lab result change… should have waited for another test before messing with the dosage I’m beginning to think!

  • Roz December 18, 2016, 10:04 pm

    I am shocked at the similarities everyone has posted on this site. Luckily I had to get blood work for my GYN since she’s trying to find the right dosage for my Bio-identical hormones. My Thyroid level was very low and she strongly suggested I see an Endocrinologist. A month later I see him and he tells me my dosage was too high & he decreased it by .25.

    The interesting part is I am wondering if the medication I was taking was the problem. I always, and everyone else should always, get Brand Synthroid. Your doctor probably didn’t advise you of that but it is very dangerous to take a hormone pill that could or could not be a little different. The color of my last refill in September was different yet from the same pharmacy Walgreens and pharmaceutical company Abbvie.

    It’s strange that the majority of comments were around September + or – 3 months. I feel awful and need to know how long it takes to calm down. My Fibromyalgia pain has increased, I perspire as if I just ran a relay, I walk around so pissed off, I don’t want to go anywhere but when I make myself go I’m ready to go home, forget about the holidays I didn’t like them anyway, and my deltoid muscles hurt so bad I wake up screaming because I can’t lift my arms up.

    I’m grateful for my Sicilian boyfriend but I need patience to deal with him on a good day. Please let me know what I can do to expedite & dismiss these symptoms. Thanks.

  • Dennis December 2, 2016, 5:36 pm

    I have A-fib that was corrected with an Ablation last Dec.’15. I needed another Cardioversion in Jan. ’16. I was back in RHYTHM. I went to my family doctor for something else in May and she wanted to check my Thyroid level, so I had a blood draw. They called and told me she increased my Levo to 75mcg. from 50mcg. I went back Nov. 1 st. and she DOUBLED it to 150 mcg. TWO DAYS LATER I went OUT OF RHYTHM! My Cardiologist told me that I SCREWED UP! I had to have another CARDIOVERSION on Nov. 30th. My Cardiologist told me to ALWAYS call him BEFORE changing ANY MEDS!

  • Dana November 28, 2016, 11:42 pm

    I am on 175 mcg of synthroid. My dr recently prescribed a mild diuretic for me to take at night. I unknowingly took a synthroid tablet rather than the similar looking diuretic. My heart felt like it was going to beat out of my chest, I could not breathe well, and my legs and face went numb. I went to the emergency room. After some time all of my symptoms eased.

  • Sharon November 24, 2016, 5:49 pm

    I have Hashimoto’s, back in July I was diagnosed with h-pylori. I was not informed that this would affect my thyroid so I continued to take 125mcg on a daily basis for 9 weeks, this caused me to have a thyroid storm. My heart rate went to 201 bpm, I experienced extreme tremors, sleeplessness loss of appetite eight loss and tachycardia.

    When I went to my Endocrinologist he thought I had Graves’ disease, and began testing after weeks of testing it was determined that I was still hypothyroid and he lowered my dose to 75mcg daily. However after 2 days all my symptoms returned and I had to stop meds again. It’s been 6 days since and I feel fatigued, and extremely emotional.

    My doctor wants to wait 2 weeks before running more blood tests. I am at a loss and I am desperate to find answers. Has anyone experienced this?

    • CAYLA December 12, 2016, 4:10 pm

      Sharon, 2 years ago I was extremely tired and was vomiting a lot. I went to the doctor and found out I had h-pylori as well has hypothyroid. They put me on 75mcg a day and I literally went insane. I couldn’t sleep was having panic attacks all the time just crazy stuff. I went back to the doctor and my test showed I was now hyper so they continued to lower my dosage.

      I now take only 15 mg of armour thyroid. I felt normal until now. Lately I have been getting lots of panic with extreme weight loss (I think like 15 pounds) and am having same symptoms I was having before. I felt very ill so I stopped taking my medicine and feel pretty normal except I’m very jittery, and can’t sleep much still, but I go to the doctor tomorrow. I know it’s hard but I hope this helps you.

  • Pete October 28, 2016, 4:12 am

    My wife has been a mess since seeing her doctor last week. Pretty much every symptom of too much medication. When she went in her TSH was low at 0.338 and her T3 was normal at 3.28 and T4 was also on the low end of normal at 1.2. Those numbers would indicate decreasing dosage or at a minimum of leaving it the same. Well the PA that saw here told her to DOUBLE her dosage from 100 to 200 micrograms of Levothyroxine. (She weighs 130 lbs). Her resting heart rate sitting at dinner was 128 BPM. I’m wondering how safe it is to wait it out.

  • Heather October 13, 2016, 11:32 am

    I started on the low dosage and didn’t see any improvement so I asked if they could up it a little. Felt okay but now every time I don’t take it at the right time in the morning or forget altogether, I have a migraine that lasts all day, despite taking the pill eventually. Is this normal?

  • David C Mills October 12, 2016, 9:27 pm

    I had a thyroidectomy 2 years ago and have been on 150 micrograms of levothyroxine. Everything was fine until about 30 days ago. Had severe palpitations and visited the ER. My endo lowered my dose to 125. Felt awful for about a week but then began to improve. The palpations subsided and it looked like that 125 would work fine.

    Then I got hit with heavy anxiety out of the blue. He lowered it again to 112 last week. Had to get a prescription for Xanax in the meantime to control the adrenaline surges. I’m praying these begin to subside over the next week. Awful experience.

    • Lakeelah Whitfield February 1, 2017, 2:31 pm

      The same thing happened to me. The anxiety came out of nowhere!!!

  • SANDRA October 10, 2016, 6:11 pm

    I am really worried about my daughter. She has been on Levothroxine (50ml) for years. About three weeks ago annual blood tests indicated that she needed an increased dose (75ml) Within a weeks she was displaying many of the symptoms above. She has Down Syndrome, and is unable to vocalize her distress. Her behavior and anxiety is resulting in her becoming aggressive. Whilst we are awaiting her to consent to blood tests she remains on 75ml. No one seems able to take my concerns seriously, putting it down to her having Down Syndrome. I am at my wits end trying to get answers.

  • Bob October 5, 2016, 12:19 am

    I’m a male in my late 50’s taking 100 mcg of Levothyroxine daily. I felt some jet lag after a 12 hour flight and decided to take an additional 88 mcg to see if it would make me feel better. Big mistake. That night I got zero sleep. The next night 1 hour. I haven’t taken any additional these past 2 days and I’m hoping tonight I get back to normal.

  • Kathy L. September 27, 2016, 4:04 pm

    I quit smoking. Most people who quit need more thyroid meds but I went hyper. Hyper symptoms is not good anytime but especially when you just quit smoking. What a nightmare but I survived and now I am a non-smoker and need less levoxyl.

  • Linda Dinnage September 15, 2016, 7:04 pm

    I have been on synthroid for 30 years and suddenly after intentional weight loss I began to be overdosed on my thyroid medication. I was reduced from .112 to .100 and my over medication only changed slightly. My doctor has reduced it to .05, cut it by half. I hope this works.

    We think I was over medicated for quite a while. I had headaches, jittery feelings, and palpitations, luckily no hyper tension, my blood pressure is very,low on the best day. I hope this will settle. Is it likely I might come off the medication or can it go lower?

  • Ann September 3, 2016, 10:09 am

    About 7 years ago I had thyroid cancer and had my thyroid completely removed. Afterward I stayed cold all the time, so cold I had a blanket year around. I was taking over 200 mg a day at first because of my weight. I was at 250 pounds. Anyway about 2 or 3 years ago I had gastric sleeve surgery and lost about 50 pounds. The doctor decreased my synthroid to 137 mg a day except on Sunday and then I take 2 of my pills making it 274 mg.

    I have started having nearly all the symptoms above just this year. Hot flashes are horrible, nearly every morning I wake up sweating even with the air on a low temp. I have had rapid heartbeat, can’t sleep more than 4 hours at night and my head bothers me all the time.

  • Nancy Lazenby August 20, 2016, 6:50 pm

    I am prescribed 100 mcg per day. This morning I accidentally took tomorrow’s dose, forgetting that I had already taken my pill. Frankly, I don’t feel any different 4 hours later. I am always depressed, in spite of taking Prozac and Trazodone along with .25 Xanax daily, and I sleep whenever I want to. I live in the deep south and no AC in the world can keep up with our heat, therefore if I am sweating I hardly notice it.

    It scared me when I discovered that I took two days worth of synthroid in one day, but otherwise I don’t notice side effects. Should I go to ER? Only option here in my town. I am caregiver for Alz husband and don’t want to get out needlessly, but this website has me worried that I might have a cardiac event!

  • Julie August 10, 2016, 4:41 am

    I have been on 0.5 mcg of synthroid for a while and was fine. But I started exercising a lot more,ingesting coconut oil and taking vitamins. I then began having these horrible, horrible bouts of panic, flushing, shaking, shortness of breath and nausea. One time I even threw up. When I realized it could be the synthroid, I quit taking it for a whole week to let me body calm down. Now I only take half – 0.25 mcg. I would not wish these symptoms on anyone! I probably should have gone to the hospital because it was that bad.

  • Cindy August 5, 2016, 9:35 am

    I purposely took 150mcg instead of 50mcg because I felt I needed that extra jump to get me thru some days… side effects of that are throbbing headaches, excessive body heat, and insomnia so far…

    • Tieara April 12, 2017, 11:57 am

      I too jumped my medication. I am on 100 a day and I’ve jumped to 300 for the past month. I am going to my Doctor tomorrow because the side effects are getting bad. I self medicated as my Doctor is so hard to get into, but the 300 is what made me feel “normal.” But now I’m getting the sh-t side effects.

  • Nancy July 4, 2016, 3:23 pm

    I was over medicated by my Dr. I knew these last 2 yrs I wasn’t feeling right. I brought to her attention we did labs and I was always told too high she said or low at times. But never did my dosage change just a day cut out or half of my pill on a Sunday instead of whole. I experienced of the symptoms and even worry that this long on a high dosage could have hurt my heart.

    I’ve had 2 ekgs done and both normal. I recently was told I was given too much meds after a new endocrinologist told me I was on a high dosage for my weight. 200mg at 130lbs. Now I am at 120lbs from loss of weight that happened within 3 weeks. I feel my body just went through a crash and said I can’t keep up no more.

    Right now I’m at 150 mg until my next labs, guessing my Dr is cutting it down little by little til we get to the right dosage. I hope these symptoms go away, and I get back on my old self.

  • Raven June 25, 2016, 10:18 pm

    I was prescribed 200 mcg. I was so upset I couldn’t loose weight because of this condition and unstable levels I increase my own dosage by take 800 mcg. That night I had horrible leg cramps that hurt for two weeks and I never did that again. I was stupid.

  • Cathy June 12, 2016, 1:25 pm

    I had been taking 75mcg one day 100mcg the next. My GP said I needed to increase my dosage to 100 a day. This happened months back. I have reduced it back to 75 now as I was living in a permanent state of being awake. If I slept it would be for about an hour to 90 mins and was ratty and irritable.

    I was also worrying about my work for no apparent reason. After routine tests my GP said to reduce my meds and only have the higher dose on two days a week. Well, today I realized… I’ve started sleeping again.

  • Laura June 7, 2016, 11:05 pm

    I have been over medicated on thyroid hormone. It is definitely not comfortable. I feel sick, dizzy, sharp headache, anxious, impaired cognition, and all the symptoms mentioned in above article. Symptoms will subside at lowering the dose. It takes about a week to feel a difference, not completely better.

    That takes a good 8 weeks. But if still feeling hyper at 10 weeks, another decrease may be in order. I just recently got a super potent dose of Synthroid 100 mcg. and developed hyper symptoms after taking only 8 days of pills. Not a happy camper. Hope this helps someone.

    • Nancy July 9, 2016, 5:26 pm

      I too was over medicated, just recently went down to 112mg from 200mg. Switched endocrinologist and that’s where the problem was found. I had been dealing with high anxiety, sleepless nights, night sweats and rapid heartbeat… I have to go back in 3 months to see where I stand. Dr doesn’t think I should have labs in a month because 3 months would be a more accurate way to determine.

      I’m hoping like everyone says I’ll feel some side edits subside within 2 weeks but I know I won’t be completely side effect free til I am on the right dosage. I have congenital hypothyroidism (born without thyroid gland).

    • Laura L Powers September 6, 2016, 9:08 pm

      I have been overmedicated accidentally for a while. I have had a hard time getting my dosage right. Do the symptoms of heart disease go away once you have gotten the right dosage? I have been on high dosage for awhile. Does anyone know if there is permanent damage?

    • Betsy January 25, 2017, 12:18 am

      Wow! Just read your comment and this is definitely what I am experiencing. I am actually taking Tirosint and my endo wanted to up my dosage to every other day alternating 25 mg and 50 mg. I also take 81.25 mg Nature thyroid.

      I only took three doses of the 50 mg and woke last night to profuse sweating and blood pressure was 138/101. I also have Addison’s disease. Talked with my doctor today and am not going to take the 50 mg anymore.

      Was experiencing heart palpitations, dizziness to where I thought I might pass out, sweating, anxiety, headache, nausea. It sucks it is so hard to get your thyroid dosage in a good range.

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