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Imitrex (Sumatriptan) Side Effects & Adverse Reactions (List)

Sumatriptan (brand names “Imitrex”) is a synthetic medication that was initially approved in 1991 for the treatment of migraine and cluster headaches.  Chemically, it is classified as a “triptan” or tryptamine-based agent and is identified as a structural analogue of various alkaloids such as bufotenine and DMT (dimethyltryptamine).  When administered following the onset of a migraine or cluster headache, Sumatriptan is clinically effective in attenuating symptoms.

However, if administered prior to the onset of a migraine or cluster headache in effort to prevent their occurrence, Sumatriptan is regarded as clinically ineffective.  Pharmacodynamically, Sumatriptan acts as a selective serotonin receptor agonist with highest affinity for 5-HT1D and 5-HT1B sites.  Agonism at the aforestated 5-HT1D and 5-HT1B receptor sites induces vasoconstriction (contraction) of the cranial and basilar arteries – offsetting the vasodilation (expansion) that may have triggered a migraine.

In addition, sumatriptan appears to reduce activity within the trigeminal nerve, thereby mitigating the upregulation in trigeminal nerve activation associated with cluster headaches.  Though many people with migraines and cluster headaches derive substantial benefit from intermittent (as-needed) administration of sumatriptan, some users experience unwanted side effects and/or adverse reactions.  While most users can cope with a mild side effect or two, some users will end up discontinuing treatment due to intolerable reactions.

Imitrex (Sumatriptan): Side Effects & Adverse Reactions (List)

Included below is a comprehensive list of potential side effects and/or adverse reactions that you may experience as a result of Imitrex (Sumatriptan); 44% of all users report side effects. The most commonly reported Sumatriptan side effects include: dizziness, drowsiness, heaviness, nausea, stomach aches, tingling, and weakness.  Other fairly common side effects include: headaches, hot/cold flashes, and tiredness.

Understand that the specific side effects, total number of side effects, and severity of respective side effects among users is subject to significant variation.  In other words, you may take Sumatriptan and find that it makes you feel nauseous, while another person may report mild dizziness with zero nausea.  A third individual may find that he/she experiences tingling throughout the body and muscle weakness, while a fourth may report zero noticeable side effects.

Anxiety: There is evidence suggesting that Imitrex (Sumatriptan) can induce anxiogenic effects in humans.  In a double-blind, placebo-controlled study involving 15 patients diagnosed with panic disorder, it was discovered that Sumatriptan significantly increased anxiety symptoms compared to the placebo.  While it is unclear as to whether the drug increases anxiety among those without preexisting anxiety disorders, many would speculate that it could.

Results from another study noted that Sumatriptan increased fear of simulated speaking compared to a placebo.  Researchers noted that cortisol concentrations increased, vigilance increased, and prolactin levels decreased.  It is hypothesized that Sumatriptan exacerbates anxiety by lowering serotonin levels in the synaptic cleft, thereby facilitating opposite serotonergic effects compared to SSRIs (which reduce anxiety).

  • Source: http://www.ncbi.nlm.nih.gov/pubmed/15820416
  • Source: http://www.ncbi.nlm.nih.gov/pubmed/23325368

Bodily pressure: Many Sumatriptan users report sensations of pressure throughout their body.  The pressure sensations are not necessarily painful and may be either localized (to one specific region) or widespread throughout various regions of the body.  Anecdotal accounts note that the pressure sensations may last anywhere from 30 minutes to several hours after taking the medication.  It is unclear as to what may cause these pressure sensations, but some speculate that it may be due to alterations in blood flow velocity and/or a result of serotonin receptor agonism.

These pressure sensations are often mild and aren’t documented as problematic by users.  If you suspect that bodily pressure may be a sign of a serious medical issue or adverse reaction, be sure to consult a medical professional for advice.  That said, experiencing sensations of pressure as the drug takes effect is considered common.

Brain fog: An unfortunate side effect that you may experience while taking Sumatriptan is “brain fog” or inability to think clearly.  As the drug kicks in, you may have a difficult time thinking clearly, organizing your thoughts, and may feel as if you’re in some sort of twilight zone – your thoughts are clouded.  There are numerous potential mechanisms that may be responsible for inducing brain fog among Sumatriptan users.

Sumatriptan increases blood flow velocity, modulates serotonin receptors (and serotonergic neurotransmission), and alters trigeminal nerve activation.  The culmination of these effects may facilitate the induction of brain fog for certain individuals.  This brain fog may linger even after the anti-headache effects of the drug have faded due to the fact that your neurotransmission will need to reset itself to a homeostatic baseline.

Burning sensations: A popularly reported side effect of Sumatriptan is that of burning sensations under and/or above the skin.  These burning sensations may occur in one specific region of the body, but could also occur in multiple areas – and may be accompanied by skin irritation and redness.  Burning sensations and skin irritation are most frequently reported by those who administer Sumatriptan via injection.

If you administer injectable Sumatriptan, burning and/or irritation may be most prominent at the specific site of injection.  Those that utilize Sumatriptan intranasal spray may find that nasal and/or oral mucosa are irritated and/or slightly burning after administration.  Fortunately, the burning sensations are usually tolerable for most users.  If these sensations become severe and/or are causing you significant distress, consult your doctor for an alternative intervention and/or modality of administration.

Cardiac events: Ingestion of Sumatriptan tablets and injections have been associated with serious cardiac complications including: coronary artery vasospasm, myocardial infarction, myocardial ischemia, transient ventricular tachycardia, and ventricular fibrillation (V-Fib).  Though these cardiac events will not occur in most users, those with preexisting cardiac complications should be closely monitored while taking Sumatriptan.  In fact, there may be safer antimigraine treatments available for ultra risk averse individuals.

The way Sumatriptan may induce these cardiac events is by constricting blood vessels.  Although vasoconstriction of blood vessels within the brain can help offset migraines which are induced by vasodilation, constriction may also occur within the peripheral nervous system – specifically around the heart.  A reduction in blood flow to areas around the heart may induce a heart attack or other serious adverse effects.

Chest pain or tightness: Another fairly common side effect of Sumatriptan is chest tightness and/or pain.  This tightness may feel as if there is intense pressure throughout your chest or within one specific area of your chest.  Chest tightness and pain can be frightening and/or anxiety-provoking because it is commonly associated with heart attacks.

Just because it is a common medication side effect does not rule out that it couldn’t be a sign of a potentially more serious issue.  For this reason, if you ever experience chest tightness, regardless of whether it’s from the medication or not, you should consult a medical professional for a full cardiac evaluation.  Assuming your cardiac function is considered healthy, and the tightness only occurs after taking Sumatriptan, it may be nothing more than an unwanted side effect.

Perhaps most troubling is the fact that Sumatriptan has been linked to cardiac events in a subset of users.  The chest tightness may stem from the fact that Sumatriptan may be constricting blood vessels, and ultimately blood flow to the heart.  If you suspect that Sumatriptan is taking a toll on your cardiac function, you may want to pursue alternative, less risky treatments.

Cognitive deficits: In addition to the already-mentioned side effect of brain fog or “clouded thinking,” you may notice cognitive impairment from Sumatriptan.  The degree to which your cognitive function suffers may be based upon the dosage of Sumatriptan administered, your baseline neurophysiology, and genetics.  For certain individuals, serotonergic modulation at 5-HT1B and 5-HT1D receptor sites has a noticeably deleterious effect upon cognition.

You may find that after taking a Sumatriptan pill, your ability to stay productive in a cognitively-demanding occupation and/or academic pursuits – is significantly hampered.  Fortunately, most cognitive deficits associated with Sumatriptan are transient and normative cognitive function is restored after Sumatriptan is eliminated from systemic circulation.  However, some users may notice that it takes a day or two for complete cognitive recovery after experiencing drug-induced deficits.

Cold flashes: After taking Sumatriptan, some individuals report feeling brief sensations of coldness throughout their body or “cold flashes.”  The cold flashes may be accompanied by chills and or “goose bumps” throughout the body.  Since the serotonin system is heavily implicated in central and peripheral thermoregulation, modulation of serotonergic processes through 5-HT1B and 5-HT1D agonism may facilitate temperature changes.

These temperature changes may cause cold flashes in a subset of individuals.  In most cases, the cold flashes and sensations of coolness throughout certain parts of the body (e.g. face) tend to subside after the effect of Sumatriptan wears off.  Keep in mind that some individuals may only experience hot flashes or an unpredictable blend of hot plus cold flashes.

Dizziness: Among the most common side effects of Sumatriptan is dizziness.  The dizziness may be mild, moderate, or severe to the extent that you feel as if your head (or the room) is spinning.  In some cases, dizziness may result from an unnecessarily high dose of Sumatriptan, but it may be induced by the combination of increased blood flow, sudden vasoconstriction, and/or serotonin receptor agonism.

For most users the dizziness is mild-to-moderate and is often most noticeable among new users.  Sometimes the dizziness may become less noticeable and/or alarming after several weeks or months of “as-needed” Sumatriptan administration.  If the dizziness is extreme and doesn’t improve over time, you may want to evaluate other potential treatment options.

Drowsiness: Don’t be surprised if Sumatriptan makes you feel drowsy, fatigued, and sluggish.  The drowsiness may be a major reason why some individuals have a difficult time thinking clearly and performing complex cognitive tasks.  Drowsiness is usually caused as a result of a downregulation in CNS activity induced by an upregulation in inhibitory neurotransmission.

If you feel drowsy while taking Sumatriptan, it is important to avoid operating a motor vehicle and/or heavy machinery.  Fortunately, the drowsiness should subside once the medication is eliminated from systemic circulation (which may take up to 14 hours).  If the drowsiness is perceived as problematic (e.g. interfering with your occupational, academic, or athletic performance), you may wish to pursue alternative antimigraine agents that aren’t associated with drowsiness.

Facial flushing: Some individuals notice that Sumatriptan causes severe facial flushing and/or redness.  Facial flushing is characterized by redness of the cheeks and forehead areas along with sensations of warmth, tingling, or temperature changes.  The facial flushing induced by Sumatriptan may be associated with changes in serotonergic neurotransmission as well as blood flow velocity throughout the CNS.

For a majority of those experiencing this side effect, facial flushing is accompanied hot flashes and/or cold flashes [resulting from drug-induced thermoregulatory modification].  While this side effect may be somewhat annoying, especially if experienced each time you take Sumatriptan, most would not consider it problematic.  If the medication is therapeutically effective for severe headaches, you’ll likely be willing to put up with a flushed face.

Fatigue: Taking Sumatriptan may sap you of physical and mental energy, leaving you to feel fatigued and lethargic for nearly an entire day.  The fatigue may be noticeable within an hour post-administration and may linger for longer than you’d expected.  If you’re struggling to combat Sumatriptan-induced fatigue, you may want to discuss some potential mitigation strategies with your doctor.

If the fatigue caused by Sumatriptan is severe, it may make sense to pursue an alternative treatment.  On the other hand, a doctor may recommend a wakefulness-promoting or stimulatory agent to offset the drug-induced fatigue associated with Sumatriptan.  For some patients, a slight tweak in dosing and/or modality of administration may improve fatigue.

Hallucinations: A rare adverse reaction to Sumatriptan is experiencing visual and/or auditory hallucinations (e.g. hearing voices).  There are numerous potential reasons for which hallucinations could occur among those taking Sumatriptan.  First, it is necessary to consider that visual hallucinations may occur directly as a result of migraines such as among those who are diagnosed as having “migraine with aura.”

If these individuals are taking Sumatriptan, some may wrongfully assume that their hallucinations were drug-induced, when in reality, they were migraine-related.  On the other hand, it is certainly possible that Sumatriptan may cause hallucinations as a standalone.  It is a chemical analogue of the hallucinogenic agent DMT.

Perhaps its modulation of serotonergic neurotransmission facilitates hallucinations, especially among those with psychiatric conditions and/or among those co-administering other psychiatric substances.   It could also be that Sumatriptan alters brain waves and/or neurochemicals to such an extent, that some users experience hypnagogic or hypnopompic hallucinations upon sleep-wakefulness transitions (and vice-versa).

Headaches: Perhaps the most ironic side effect of Sumatriptan is headaches.  This is a treatment for cluster headaches and migraines, yet in some users, it may cause headaches.  While most of the headaches that it causes as a side effect are reported as mild, anecdotal accounts have suggested that Sumatriptan can cause very severe headaches as well.

Since the pathoetiological underpinnings of cluster headaches and/or migraines are subject to individual variation, we cannot assume that Sumatriptan will be 100% effective in all users.  Its mechanism of action as a serotonin receptor agonist induces vasoconstriction, which can cause headaches for some individuals.  If Sumatriptan is making your headaches worse and/or more severe, your underlying problem may be vasoconstriction and/or that you were taking too high of a dose.

Heart palpitations: Certain individuals may experience heart palpitations perceived as abnormally fast, loud, irregular, and/or fluttery heartbeats.  These palpitations are usually associated with anxiety, and since Sumatriptan can be anxiogenic for some users, palpitations may result.  In some cases, these palpitations may occur along with chest pressure and/or pain – leading you to believe that you’re experiencing a legitimate heart attack.

As was already mentioned, if you are concerned about your heart health, consult a cardiologist and get a full analysis to rule out any untreated cardiac conditions.  Sometimes palpitations may subside after your body adapts to the effects of Sumatriptan.  Other times, your doctor may need to reduce the dosing of your Sumatriptan to decrease these palpitations.

Heaviness sensation: Arguably the single most common side effect reported by Sumatriptan users is a sensation of heaviness throughout the body.  Most users have noted that the heaviness is most noticeable in the shoulders and arms.  It may feel as if someone strapped a ton of weights to various parts of your body and simultaneously extracted every last ounce of volitional energy necessary to move your body.

This sudden onset of heaviness may be accompanied by drowsiness, fatigue, impaired coordination, and/or muscle weakness.  Those that experience heaviness may struggle to engage in any physical activity and may not feel like doing anything other than relaxing on the couch or resting in bed.  Since this is a common side effect, you may need to simply learn to cope with it if you’d like to continue Sumatriptan treatment.

Hot flashes: Many individuals experience hot flashes, or a potent (yet transient) sensation of warmth and/or heat throughout the body as a side effect.  These hot flashes may be frequent and/or long lasting, but usually diminish within 14 hours post-administration.  Sumatriptan may cause hot flashes by stimulating serotonin receptors, which in turn alter serotonergic transmission implicated in thermoregulatory signaling.

Slight adjustments in thermoregulatory signaling could lead to hot flashes, as well as facial flushing and/or sweating.  In some cases, individuals may notice a combination of hot flashes and cold flashes during treatment.  Since hot flashes are not considered a harmful side effect, most individuals will put up with them as long as the medication is effectively inhibiting headaches.

Irritability: Though Sumatriptan isn’t technically classified as a psychiatric drug, it affects serotonergic neurotransmission, which is implicated in many models of psychiatric disorders.  It agonizes 5-HT1D and 5-HT1B which has been shown to decrease extracellular concentrations of serotonin.  This is thought to impair neuron-to-neuron signaling, which may lead some users to feel more irritable than usual.

This irritability may be accompanied by mood swings after taking Sumatriptan, especially at high doses.  The higher the dosage a person ingests, the more significant the neurophysiological modulation and greater potential of irritability.  Those who dislike the drug-induced irritability may want to consider a dosage reduction, alternative treatment, and/or adjunct to address this side effect.

Itchiness: A relatively uncommon Sumatriptan side effect is itchiness and/or itchy skin.  This itchiness may be accompanied by a skin rash, redness, burning, or tingling sensations – especially among those who administer the injectable format.  To rule out serious complications and/or an allergic reaction, those that become extremely itchy should discuss it with a medical professional.

Understand that most people will not experience severe itchiness while taking Sumatriptan, but it has been reported.  Itchiness is thought to occur more among those who administer it via intravenous injection as opposed to taking oral tablets.  In some cases, the itchiness may be associated with tingling and/or burning sensations throughout the skin.

Jaw pain: Another uncomfortable side effect occurring in some Sumatriptan users is jaw pain.  Your entire jaw may start to ache and you may feel as if there’s increased pressure in the areas surrounding your jaw.  Those that experience moderate-to-severe jaw pain each time they ingest this medication may eventually want to consider alternative interventions with less debilitating side effects.

Even if the drug is successfully alleviating your headaches, the fact that it is inducing jaw pain is disconcerting.  Though the jaw pain may not be severe, there are usually alternative medications that can effectively treat headaches without making your jaw feel as if it’s about to explode.  The mechanisms behind the jaw pain are unclear, but it may be a result of alterations in blood flow.

Lightheadedness: Those experiencing cluster headaches and/or migraines may feel lightheaded during onset of a headache, however, Sumatriptan is also capable of causing lightheadedness.  Many people report extreme lightheadedness and dizziness while taking Sumatriptan.  There are numerous ways by which Sumatriptan could be inducing lightheadedness such as: vasoconstriction, serotonin modulation, and altered blood flow.

Since many users have reported that Sumatriptan significantly decreased their blood pressure, the lightheadedness may also be associated with hypotension.  For this reason, it may be necessary to regularly monitor your blood pressure while taking Sumatriptan.  If your blood pressure drops low, lightheadedness may result and could lead to fainting spells.

Loss of balance / coordination: Although migraines may render you relatively immobile and unable to walk, Sumatriptan may substantially affect your balance and/or coordination.  Once the drug kicks in, you may feel slightly intoxicated and as if you need to sit and/or lie down.  Since your balance and coordination may be compromised, you may want to avoid engaging in any physically demanding tasks, exercise, and/or athletics.

Also, since your balance and coordination may be temporarily downgraded while under the influence of Sumatriptan, you should avoid operating a motor vehicle or machinery.  Most people will notice that their fine motor skills return within half-a-day after their Sumatriptan dose; some regain these abilities sooner than later.  To minimize the severity of coordination and/or balance loss – consider taking a small dose.

Low blood pressure: A small percentage of individuals will notice that their blood pressure changes, perhaps significantly, while taking Sumatriptan.  If you have a history of blood pressure abnormalities, it is important to carefully monitor it during treatment.  Some have claimed that their blood pressure dipped to dangerously low levels as a result of this drug.

Realize that this side effect is not considered common, per se, but has been reported.  Signs of low blood pressure include dizziness, lightheadedness, and queasiness.  Individuals that are taking antihypertensive agents should be especially cognizant of this possible effect.

Muscle aches or stiffness: Some people may experience severe muscle aches and/or joint stiffness after taking Sumatriptan.  The achiness and stiffness may be caused by Sumatriptan-induced anxiety, but could also be a result of unknown neurophysiological mechanisms.  Perhaps the drug may be altering processes in the brain to increase muscle tension or may be modulating perceptual processes, leading some users to perceive aches throughout their musculature.

That said, some individuals may perceive muscle aches as being a side effect of the Sumatriptan medication, when in reality, they are a byproduct of the cluster headache, migraine headache, or stress resulting from the headache.  If the aches are induced by the medication, they should subside when a majority of the drug is eliminated from systemic circulation.  If you find this particular side effect to be overwhelming, there are always other medications to consider.

Nausea: If you feel nauseated after each dose of Sumatriptan, you are certainly not alone.  Nausea is regarded as being among the most common side effects of this drug and may lead to vomiting.  Since nausea is also associated with severe migraines, it may be difficult to distinguish whether the nausea resulted from Sumatriptan, the migraine, or possibly both (simultaneously).

Severe nausea may be a sign that you are unable to tolerate Sumatriptan and/or are taking too high of a dose.  Sometimes a dosage reduction will be helpful for decreasing nausea, but may fail to fully address headache symptoms.  The nausea may occur intermittently and/or persist for an extended duration following administration of Sumatriptan.  If nausea is overwhelming, discuss it with your doctor as he/she may recommend an adjunct antiemetic or alternative medication.

Numbness: Users have reported that various parts of their body feel numb after taking Sumatriptan.  This numbness may be accompanied by feelings of muscle weakness and/or tactile sensations such as burning, itching, or prickling sensations.  The underlying mechanisms by which this numbness is induced aren’t clear, but it could be that numbness is a result of restricted peripheral blood flow to certain regions.

Blood flow restriction is thought to occur as a result of vasoconstriction.  Among those taking high doses of Sumatriptan, the numbness feeling may be more prominent than low dose users.  However, it is possible that among those with already-poor circulation, numbness may occur following every Sumatriptan administration.

Skin rash: Certain users of Sumatriptan may develop skin rash following administration.  The skin rash may be accompanied by itchiness and could be localized to one particular area of the body or widespread.  It is important to consider that a skin rash may be a sign that a person is allergic to Sumatriptan and may need to discontinue treatment.

On the other hand, an isolated rash in one particular area may have resulted from excessive irritation following Sumatriptan injection.  Regardless of the size of the rash, individuals should seek medical verification that the rash isn’t a sign of a more serious adverse reaction or undetected condition.  Most people that end up with a severe skin rash from Sumatriptan will discontinue and/or change medications.

Sleep disturbances: Many individuals report changes in their sleep quality and/or quantity while taking Sumatriptan – especially if administered in the afternoon/evening.  These changes in sleep may be a result of serotonin receptor stimulation, which in turn, reduces extracellular levels of serotonin.  Reduced extracellular levels of serotonin may trigger insomnia or frequent waking throughout the night in a subset of users.

Manipulating serotonin receptor activity could also facilitate changes in a person’s circadian rhythm, ultimately affecting their sleep-wake cycle.  Serotonin receptor agonism may also provoke weird dreams and/or nightmares if administered in the latter half of the day.  Those who report sleep disturbances from Sumatriptan may want to consider alternative options for treating the onset of evening cluster headaches and migraines.

Stomach aches: Some individuals experience mild to moderate stomach aches after taking Sumatriptan.  These stomach aches may be a result of drug-induced gastrointestinal irritation, which could facilitate the occurrence of diarrhea, constipation, indigestion, or flatulence.  Among those with debilitating stomach aches after taking Sumatriptan, medical literature recommends taking it with food or after a meal.

In some cases, stomach aches may occur among those who have administered agents that are contraindicated with Sumatriptan.  Most users are able to put up with a minor stomach ache or two as long as their headache symptoms are addressed by the medication.  However, if stomach aches are intense, and only occur following Sumatriptan ingestion, alternative options should be assessed.

Sulfhemoglobinemia: Those taking high doses or supratherapeutic doses of Sumatriptan may experience a condition known as sulfhemoglobinemia.  This is an extreme adverse reaction to Sumatriptan characterized by abnormally high concentrations of sulfhemoglobin (SulfHb) within the bloodstream.  As a result, sulfur atoms maneuver their way into hemoglobin molecules and reduce oxygenation.

Individuals with sulfhemoglobinemia tend to experience bluish or greenish blood, skin, and/or mucous membranes.  While a majority of those experiencing sulfhemoglobinemia will recover within several weeks following Sumatriptan discontinuation, sometimes blood transfusions are necessary.  If you notice signs of sulfhemoglobinemia, immediate medical attention is warranted.

Sweating: Another relatively common reaction to Sumatriptan is an increase in bodily sweating.  This excessive sweating, technically referred to as “hyperhidrosis,” may soak your clothes during the daytime and your bed sheets at night.  Sweating usually becomes most prominent within an hour or two of administration and tends to decline as your body excretes Sumatriptan.

Some speculate that the sweating may be related to serotonergic-induced thermoregulatory modifications.  These modifications in thermoregulation may lead to sweating accompanied by hot/cold flashes and/or facial flushing.  It could also be that Sumatriptan inhibits stimulation of sweat glands, leading to an overproduction of sweat throughout the body or within particular areas.

Tingling sensations: An uncomfortable side effect that many Sumatriptan users notice is tingling.  Those that experience tingling tend to report that it emerges within 30 minutes of ingesting their dose and note that it may occur in one particular region (e.g. throughout the arms) or may be widespread throughout the entire body.

The tingling may feel as if it’s coming from underneath the skin and has been described as akin to pins and needles or prickling sensations.  Some have reported tingling along with burning sensations or general numbness.  While this tingling may be uncomfortable, most are willing to cope with these transient prickles as long as their headaches are improving.

Tiredness: As was mentioned, Sumatriptan may make you feel drowsy throughout the day and/or excessively fatigued.  It could also induce significant tiredness and somnolence, leading you to feel as if you need to take a nap and/or sleep more than usual.  In fact, a small percentage of users may find that Sumatriptan helps them fall asleep by counteracting insomnia.

In any regard, this tiredness may be unwanted, especially if you’re taking Sumatriptan during the daytime such as at work or school.  Those who wish to counteract the excessive tiredness (and tiredness-induced cognitive deficits) may want to discuss dosage reduction and/or adjunct wakefulness promoting agents with a medical professional.  That said, the tiredness eventually subsides and wakefulness reemerges once the medication is cleared from circulation.

Vertigo: It was noted that many people taking Sumatriptan experience dizziness, sometimes to a significant extent.  A specific type of dizziness reported among users is vertigo or a sensation that a person’s surrounding environment is spinning, swaying, or moving.  Those who experience vertigo as a side effect are also more likely to report balance problems, nausea, sweating, and vomiting.

Experiencing vertigo may lead a person taking Sumatriptan to remain in a seated or lying down until it subsides.  Understand that vertigo may be worsened by physical movement and/or activity.  In effort to reduce the severity of vertigo, only the smallest effective dosage of Sumatriptan should be used for headaches; large doses may exacerbate this unfavorable reaction.

Vision changes: Though Sumatriptan doesn’t actually damage the eyes, it can lead to changes in visual perception.  Since it is capable of altering cerebral blood flow and serotonin activity, it may be that these alterations affect visual processing systems in the brain.  Slight alterations in visual processing systems may lead a user to speculate that Sumatriptan is damaging eyesight.

In reality, what’s likely happening is that the visual perception systems are slightly amiss, leading to perceived blurred vision.  That said, don’t assume that the drug is causing the problem, eyesight can gradually worsen over time, especially among those who are middle-aged.  Consult an ophthalmologist for regular eyesight assessments throughout treatment to ensure that no actual damage was induced by the drug.

Vomiting: In a small percentage of Sumatriptan users, the side effect of vomiting may occur.  Vomiting may be a sign that a user took too high of a dose for their particular physiology, but it may also signify intolerability to Sumatriptan.  Vomiting could also be an indirect result of another drug-induced side effect such as dizziness, nausea, vertigo, etc. – or a byproduct of a severe migraine.

If after each dose of Sumatriptan you end up vomiting, chances are there’s a more tolerable medication on the market for your needs.  Though vomiting is a relatively rare adverse reaction, it should be promptly reported to a medical professional.  Sometimes a simple dosage reduction is capable of reducing drug-induced vomiting.

Weakness: Once Sumatriptan takes effect, you may suddenly feel extremely weak and unable to engage in any physically-demanding tasks.  This weakness may be accompanied by muscle and/or joint pain, but could occur as a standalone side effect.  As a result of weakness, users report having a tough time lifting their arms and/or moving their legs.

Understand that this weakness could be a result of other side effects such as drowsiness and/or fatigue.  The weakness may be most intense within the first couple of hours following administration and may fade once some of the drug is excreted from the body.  As the effect of Sumatriptan subsides, your energy should return along with your strength.

Note: A majority of Sumatriptan users will not experience every single aforestated side effect.  In fact, some individuals taking Sumatriptan will experience zero noticeable side effects.  If you have a question about any specific side effect(s), do not hesitate to contact your doctor.

Variables that influence Imitrex (Sumatriptan) side effects

The side effects of Sumatriptan are subject to significant interindividual variation.  Variables that influence the number, intensity, and specific side effects a person experiences following Sumatriptan administration include: dosage, modality of administration, frequency of usage, co-administered substances, as well as various individual factors.  When attempting to understand the side effects you’re experiencing from Sumatriptan, consider the influence of these variables.

  1. Dosage (High vs. Low)

The dosage of Imitrex (Sumatriptan) administered can have a major impact on the severity and/or number of side effects that you experience.  In general, those taking higher doses of Sumatriptan are likely to experience a greater number of side effects and/or side effects of greater severity than those taking lower doses.  This is due to the fact that higher doses exert greater influence over homeostatic neurophysiological processes.

Sumatriptan functions as a serotonin receptor agonist, but the potency of this agonism is likely amplified at higher doses (e.g. 100 mg) compared to lower ones (e.g. 25 mg).  Amplification of serotonin receptor agonism may lead to more substantial vasoconstriction and/or trigeminal nerve modulation – ultimately triggering unwanted side effects.  Moreover, after ingesting a large oral dose of Sumatriptan, MAO enzymes will be taxed to a greater extent due to the fact that they play a role in metabolism and excretion – another potential reason for side effects.

Whenever there’s a larger amount of the drug to metabolize and excrete, users are at greater risk for side effects.  This is why certain adverse reactions such as sulfhemoglobinemia are only understood to affect those taking extremely high doses.  Those taking extremely low doses will be subject to fewer side effects because there’s less overall serotonergic modulation and the smaller quantity of Sumatriptan is efficiently absorbed, metabolized, and excreted.

  1. Modality of administration

It is important to consider the modality by which Sumatriptan is administered whenever contemplating the side effects.  Sumatriptan is manufactured in several formats including: oral tablets, injections, and nasal inhalers.  Though all three formats are comprised of the same Sumatriptan chemical, many users report slightly different side effect profiles based on the way in which it is delivered.

Some individuals are able to tolerate one modality of administration (e.g. tablet) better than another (e.g. injection).  There is no universal consensus in regards to whether one specific format of the drug yields fewer side effects than another.  Keep in mind that some side effects may be directly contingent upon the way you’ve been taking Sumatriptan.

Tablet: An extremely common way by which Sumatriptan is administered is in the form of tablets.  Tablets are often preferred over nasal inhalers and/or injections due to the fact that they don’t cause irritation (in the nasal cavity and/or skin) following administration.  Tablets undergo presystemic metabolism, and as a result, have a significantly lower bioavailability.

As a result of the lower bioavailability, a user needs to take a greater dose of the Sumatriptan compared to intranasal and/or injectable formats for an antimigraine effect.  The greater doses associated with tablet formats indicates that a larger amount of Sumatriptan will be absorbed, metabolized, and distributed throughout the body.  For this reason, it could be hypothesized that Sumatriptan in tablet form may be most likely to provoke side effects.

That said, tablets do not involve pricking the skin such as would occur with injectable Sumatriptan.  Many people report skin irritation as a result of injections and those administering Sumatriptan in the form of an inhaler (nasal spray) notice nasal cavity discomfort.  In some cases, irritation associated with injectable and/or intranasal Sumatriptan may be the single most severe side effect – making tablet form more tolerable among a subset of users.

Common adverse reactions to Sumatriptan tablets include:

  • Chest pain
  • Fatigue
  • Hot/cold sensations
  • Jaw pain
  • Neck pain
  • Paresthesia
  • Sensations of pressure
  • Throat pain
  • Vertigo

Intranasal: Sumatriptan is also manufactured in the form of a nasal spray at dosages of 5 mg, 10 mg, and 20 mg.  It is unclear as to whether the intranasal format is as effective as other formats, but it appears as though intranasal Sumatriptan has slightly greater bioavailability than oral tablets.  Superior bioavailability means that less of the drug needs to be administered for the desired therapeutic effect.

Compared to oral tablet forms of Sumatriptan, intranasally administered Sumatriptan doesn’t undergo extensive presystemic metabolism.  Based on bioavailability alone, one might speculate that nasal spray would be better tolerated than tablet formats.  However, many fail to consider that intranasal spray can be uncomfortable and cause may side effects as a result of inhaling a chemical through the nasal cavity.

Many have claimed that their entire nasal cavity for awhile after administration.  Others may report increased lightheadedness and/or dizziness due to the fact that the drug is delivered quickly to the CNS.  Those who prefer a gradual onset of action and/or prolonged elimination period may find oral forms of Sumatriptan to be more tolerable.

Most common adverse reactions to Sumatriptan nasal spray include:

  • Burning sensations
  • Dizziness (Vertigo)
  • Nasal cavity or sinus discomfort
  • Nausea
  • Sore throat
  • Unpleasant taste
  • Vertigo

Injection: When compared to other modalities of administration, injectable Imitrex (Sumatriptan succinate) has a bioavailability of 97%.  As a result of this high bioavailability, a smaller amount of the drug can be administered for significant therapeutic relief.  Dosages of injectable Sumatriptan range from 1 mg to 6 mg – with 6 mg being the highest recommended single-dose.

It is understood that injectable format of Sumatriptan provides the most rapid cluster headache and migraine relief.  However, injectable Sumatriptan is also associated with burning of the skin near the injection site, and may be more likely to cause skin tingling, numbness, and/or a rash.  Some believe that the injectable format may also increase likelihood of cardiac events due to its quicker absorption.

Most common adverse effects to Sumatriptan injections include:

  • Burning sensations
  • Dizziness
  • Facial flushing
  • Heaviness feeling
  • Hot/cold sensations
  • Injection site reactions
  • Numbness
  • Pressure sensations
  • Skin tingling
  • Tightness
  1. Frequency of usage

The frequency at which you use Imitrex (Sumatriptan) to treat cluster headaches and/or migraines could also influence the side effects that you experience.  Someone who uses the drug with maximal frequency such as multiple times per day, may experience more (or possibly fewer) side effects than an infrequent user.  A subset of frequent users may experience fewer side effects due to the fact that their body has fully adapted to receiving the drug at a high frequency.

In most cases, whenever someone begins taking a drug, the side effects are most significant in the first few weeks of treatment.  However, eventually the body adjusts to the presence of the drug and side effects often diminish in intensity and/or may subside altogether.  Though side effects may dwindle significantly for some chronic, high-frequency users, this will not be the case for everyone.

Some individuals may build up a tolerance to the effects of Sumatriptan and continuously need to increase their dosage to maintain therapeutic efficacy.  As a result of continuous dosage increases, side effects may become more severe.  Furthermore, some individuals may never fully adjust to the drug and/or could find that side effects actually worsen as a result of high-frequency usage.

The same theoretical framework applies to lower-frequency users of Sumatriptan.  A subset of infrequent users may report a significant number of side effects due to lack of neurophysiological adaptation.  Among these users, such as those taking Sumatriptan once every few weeks, may feel as if their entire CNS is shocked each time it receives the drug.

On the other hand, some infrequent users may be able to get away with taking lower doses of the drug due to lack of tolerance.  As a result of infrequent and low dose administration, a subset of infrequent users may experience fewer and/or less severe side effects.  In summary, the frequency at which Sumatriptan is administered will likely influence side effects, but whether a high/low frequency reduces or exacerbates side effects will be subject to interindividual variation.

  1. Co-administered agents

Taking other drugs and/or supplements along with Imitrex may exacerbate and/or reduce the number and severity of side effects you experience.  If you’re taking a medication or supplement in addition to Imitrex, it is important to discuss potential contraindications with your doctor.  Co-administered substances could interact with Sumatriptan’s pharmacokinetics, pharmacodynamics, or possibly both.

Since Sumatriptan modulates serotonergic processes, any serotonergic agent taken along with Sumatriptan could be problematic.  While most evidence suggests that medications such as SSRIs, MAOIs, and lithium are safe when administered along with Sumatriptan, select cases of serotonin syndrome have been reported.  One such case involved a 65-year-old woman who experienced serotonin syndrome after taking Sumatriptan and Paxil.

Researchers believe that overstimulation of the 5-HT1A receptors in the raphe nuclei region [resulting from Sumatriptan plus Paxil] caused the serotonin syndrome.  All serotonergic agents should be used with caution and under careful medical supervision when administered along with Sumatriptan.  Additionally, it could be hypothesized that certain co-administered agents will alter the pharmacokinetics of Sumatriptan, possibly leading to adverse effects.

Alternatively, some agents may mitigate various side effects induced by Sumatriptan.  For example, someone who drinks a cup of coffee just before or after taking Sumatriptan may find that the caffeine content offsets Sumatriptan-induced cognitive impairment, drowsiness, and/or fatigue that they would’ve otherwise experienced.  If you’re taking another substance along with Sumatriptan, consider that it may be offsetting or blunting certain Sumatriptan side effects.

  • Source: http://www.ncbi.nlm.nih.gov/pubmed/15868995
  1. Individual factors

Whenever considering side effects resulting from a specific drug, individual factors should be considered.  Even if someone is taking the same Sumatriptan: format (e.g. tablet), dosage (e.g. 50 mg), and with the same frequency – side effects could still slightly differ between users.  Miscellaneous individual factors such as a person’s: genetics, general health, sleep hygiene, stress level, etc. – may predict the severity of side effects experienced while taking Sumatriptan.

  • General health: A person’s general health may influence propensity to experience side effects. Someone with a history of cardiac abnormalities may be more susceptible to adverse cardiac events while taking Sumatriptan compared to someone with no prior cardiac problems.  Hypothetically, another example could be that someone with a history of hypotension would be more likely to experience Sumatriptan-induced hypotension than someone without a history of hypotension.  Also consider that someone with poor general health is more likely to be taking medications for other health conditions that may exacerbate certain side effects associated with Sumatriptan.
  • Genetics: Though Sumatriptan isn’t understood to undergo extensive hepatic metabolism, various genes likely predict how someone reacts to the drug. Gene expression influences a person’s entire neurophysiology and will be predictive of whether someone derives benefit from Sumatriptan and whether the side effects are severe.  Someone with a particular gene (or set of genes) may experience no noticeable side effects from Sumatriptan, while another person with a different set of genes may experience debilitating side effects.
  • Sleep: A person’s sleep cycle can have a huge impact on day-to-day health and well-being. Not getting enough sleep can trigger cognitive deficits, drowsiness, lethargy, and a host of other unwanted effects.  Someone who has poor sleep hygiene while taking Sumatriptan may report more severe side effects than someone who sticks to a regular sleep schedule.  This is because the physiological response associated with sleep deprivation may be synergistic with the unwanted side effects of Sumatriptan, thereby amplifying the severity.
  • Stress: It is necessary to evaluate your stress level and consider that stress may exacerbate certain side effects. Poor stress management can lead to an array of physical symptoms (such as heart palpitations, sweating, frequent urination, etc.) as well as psychological effects such as brain fog, racing thoughts, depersonalization, etc.  Someone with high stress or anxiety may find that side effects from Sumatriptan are exacerbated as a result of stress.  Moreover, some Sumatriptan users may mistakenly attribute the effects of stress to the Sumatriptan medication.

Imitrex (Sumatriptan): Do the antimigraine benefits outweigh the side effects?

Whenever taking Imitrex (Sumatriptan), or any drug for that matter, it is necessary to evaluate whether the therapeutic benefits outweigh the unwanted side effects.  In other words, you’ll need to ask yourself whether the cluster headache and/or migraine relief derived from Sumatriptan substantial enough, relative to the side effects, to justify continued usage.  A subset of Sumatriptan users may notice that the drug provides significant benefits without any side effects.

If you are in the camp of all benefits without any unwanted side effects, continued usage makes a lot of sense.  Even if you are able to attain significant headache relief with just a few minor side effects, continued usage is likely your best bet.  However, deciding whether to continue treatment can get a bit dicey if you’re experiencing many unwanted side effects while simultaneously getting a bit of headache relief.

For those that are having difficulty deciding whether to continue with Sumatriptan or discontinue, it is recommended to weigh both the side effects and benefits with a medical professional.  It is also extremely helpful to maintain a journal throughout treatment to get a long-term, “big picture” understanding of subjective efficacy and tolerability.  If you’re experiencing dizziness and mild chest pressure, but are otherwise getting solid headache relief from Sumatriptan, you may want to continue using.

On the other hand, if you have a history of cardiac problems and experience chest pain and/or cardiac abnormalities from the drug – you’ll probably want to discontinue for general safety (to avoid a potential cardiac event).  Other Sumatriptan users may find themselves dealing with either: severe, debilitating side effects and/or limited efficacy.  In both cases (debilitating side effects and lack of efficacy), discontinuation of Sumatriptan in favor of another treatment is common sense.

Possible ways to reduce Imitrex (Sumatriptan) side effects

If you’ve been taking Imitrex (Sumatriptan) and are experiencing severe and/or unwanted side effects, you may want to consider some potential side effect mitigation strategies.  Prior to implementing any of these strategies, it is recommended to verify safety and hypothesized efficacy with a medical professional.  Examples of ways to decrease Imitrex side effects include: dosage reduction, altering modality of administration, avoiding other agents, adding other agents, and/or administering with food.

  1. Dosage reduction: If you’re experiencing severe side effects from Imitrex, it could be a result of the dosing. As was already discussed, higher dosages elicit greater neurophysiological change compared to lower ones and are more likely to provoke side effects. If you suspect that your dosage is too high, work with your doctor to find the “minimal effective dose” – or quantity of the drug that treats your headaches without inducing extreme side effects.
  2. Alter format: There are three formats of Sumatriptan available including: tablet, injectable, and intranasal spray. If you’re taking one format and dislike the side effects, you may want to try another format (or perhaps experiment with all three) to determine whether side effects are reduced. Some people report significantly fewer side effects as a result of a format switch (e.g. from oral to injectable).
  3. Avoid other agents: Some drugs are thought to interact with Sumatriptan, especially those that modulate concurrently modulate the neurotransmission of serotonin. If you’re taking another serotonergic agent such as a 5-HT receptor agonist or an MAO-A inhibitor, side effects may be more likely. You may want to discuss stopping these agents with your doctor.  Also, if you’re taking unnecessary supplements with Sumatriptan, you may want to discontinue them for awhile to assess whether side effects improve. There could be some unknown interactions between Sumatriptan and certain supplements that are causing unwanted side effects.
  4. Add another agent: In some cases, assuming Sumatriptan is fairly well tolerated but one or two side effects problematic, adding another drug or supplement may be helpful. For example, someone who ends up administering Sumatriptan during a work-day to treat a cluster headache may find that he/she cannot perform as well on cognitively-demanding tasks. Perhaps a medical professional may recommend a safe supplement or drug that can be taken along with Sumatriptan so that the person attains headache relief without the transient cognitive dysfunction.
  5. Take with food: Those that are experiencing gastrointestinal side effects after each dose of Sumatriptan may want to consider taking it with food or after a meal. Meals may reduce gastrointestinal burden and/or irritation induced by Sumatriptan. Specifically, individuals may want to consider taking Sumatriptan with a high fat meal as “high fat” meals increase the maximum serum concentrations and area under the curve by 15% and 12% (respectively).

Have you experienced Imitrex (Sumatriptan) side effects?

If you’ve taken Sumatriptan, feel free to share whether you’ve experienced any side effects in the comments section below.  To help others get a better understanding of your situation, share some additional details like: why you’re taking Sumatriptan (e.g. migraines), your dosage, modality of administration (e.g. oral tablets), whether you use any other substances (medications, supplements, etc.), and how long you’ve been taking it.  In your anecdotal experience, what side effects resulting from Sumatriptan would you consider to be most problematic?

For those that have been taking Sumatriptan for an extended period of time, have you found that side effects increased, decreased, or remained the same (in terms of number and intensity)?  In other words, after several months of using the drug, did tolerability improve?  Understand that no drug, including Sumatriptan, should be regarded as a utopian cluster headache and/or migraine treatment.

Since every pharmaceutical treatment is associated with side effects, it is up to you to determine whether the therapeutic benefits outweigh the unwanted side effects.  Always work with your doctor, listen to your body, and realize that even if you don’t tolerate Sumatriptan well, there are a multitude of other interventions you could utilize.

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2 thoughts on “Imitrex (Sumatriptan) Side Effects & Adverse Reactions (List)”

  1. My biggest side effects are painful joints and muscles, chest tightness and sore throat. I feel as though I’ve been run over by a Mac truck for the entire day after taking imetrex. But it gets rid of my migraine so I will continue to deal with the side effects.

  2. Hello I have been experiencing a rapid onset of anxiety symptoms following an extended period of taking high doses of Sumatriptan for migraines. I’ve had migraine nearly every day for two or three weeks and taken around 20 pills over that time. In the last two weeks I’ve had increasing occurrences of panic attacks and anxiety.


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