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Hydroxyzine Side Effects & Adverse Reactions (List)

Hydroxyzine is an antihistaminergic drug that was initially marketed in the 1950s by Pfizer.  It is manufactured under the brand names Vistaril and Atarax, but widely purchased as a generic.  Although hydroxyzine has been on the market for over half a century (50+ years), it is still commonly utilized by medical practitioners in a variety of scenarios including: as a perioperative adjunct anesthetic and analgesic; as an anxiolytic for generalized anxiety disorder (GAD) and panic disorder; and as an antiallergic agent to combat allergic reactions (e.g. atopic dermatitis or hives).

In some cases, it is also prescribed to attenuate the severity of alcohol withdrawal and opiate withdrawal symptoms.  Hydroxyzine often considered a unique pharmaceutical intervention in that its pharmacodynamics primarily involve targeting the H1 receptor as an inverse agonist and, to a lesser extent, the 5-HT2A receptor as an antagonist.  This delivers a combination of antihistaminergic and antiserotonergic effects that alleviate anxiety, decrease allergic responses, and improve sleep quality.

Due to the fact that hydroxyzine has a low potential for abuse, addiction, dependence, and a slow tolerance onset – many believe it is advantageous over other anxiolytics such as benzodiazepines.  Although hydroxyzine may be an ideal treatment for certain individuals, it is not devoid of side effects and tolerability issues.  Many users experience unwanted hydroxyzine side effects, leading them to discontinue treatment and pursue other pharmaceutical options.

Hydroxyzine Side Effects & Adverse Reactions (List)

Included below is a list of hydroxyzine side effects and adverse reactions as reported by the literature, as well as via anecdotes.  Keep in mind that not all users will experience unwanted side effects – some may experience none.  Others may experience a laundry list of adverse effects from hydroxyzine, leading them to discontinue usage.

Realize that the number of side effects you experience, as well as their respective severities, are subject to significant individual variation.  That said, published studies suggest that the most commonly reported side effects among hydroxyzine users include: transient sleepiness, dry mouth, insomnia, weight gain, and difficulty concentrating.

Appetite increases: Certain individuals may notice that after taking hydroxyzine, their appetite increases.  An increased appetite generally leads to greater daily caloric intake and/or difficulty resisting food cravings.  This in turn may lead to weight gain with continued treatment, a side effect reported by around 12% of hydroxyzine users.

It isn’t known exactly what causes some individuals to experience an increase in appetite.  We could speculate that there may be downregulated activity in areas of the brain involved in registering satiation, hormone alterations (e.g. increases in ghrelin), or other factors that may lead to increased food consumption.  If your stomach feels empty all the time while taking hydroxyzine, know that increased appetite is a documented side effect.

Blurred vision: If after taking hydroxyzine your vision seems to have blurred, realize that this is a common side effect.  Medications that cause blurred vision may be affecting activation within the visual cortex, thereby leading to a hazy projection of your external surroundings.  This side effect may be especially confusing among those who already have visual abnormalities and wear contacts or glasses.

It is possible that blurred vision from taking hydroxyzine is transient and will subside with continued usage.  However, dosage reductions should be considered as a potential strategy to reduce the degree to which vision is blurred while taking this medication.  Understand that the drug likely isn’t affecting your eyes directly, but it’s altering activity in your visual cortex, leading you to believe that suddenly your eyes aren’t functioning to their full capacity.

Brain fog: Arguably the most debilitating side effect of any antihistamine is “brain fog” or clouded thinking.  Though brain fog is a slang term to describe decreased clarity of thought and isn’t well understood by medical professionals, it is common among those taking antihistaminergics.  Histamine is thought to play a role in regulating arousal and wakefulness, and when an H1 receptor inverse agonist is administered such as hydroxyzine, a user may feel as if they’ve become an incoherent, brain-dead, sleep-walking zombie.

Unfortunately, there aren’t really any major shortcuts around the brain fog induced by hydroxyzine.  Sometimes the antihistaminergic effects diminish with repeated usage and the brain fog improves.  Some users may want to consider reducing dosages, shifting the time of day at which hydroxyzine is administered, or perhaps utilizing a stimulant to combat the antihistaminergic clouding of consciousness.

  • Source: http://www.ncbi.nlm.nih.gov/pubmed/20851648

Cognitive deficits: Deficits in cognitive function may be noted among some hydroxyzine users.  If before taking hydroxyzine you had no difficulties with writing, organization of thoughts, mathematics, problem solving, reading, and/or comprehension – but after taking hydroxyzine you struggle – it’s likely a result of the drug.  Antihistaminergics are known to impair various aspects of executive function.

This may be a result of decreased sympathetic activation (and diminished physiologic arousal), reduced stimulatory neurotransmission (e.g. dopamine/norepinephrine), and altered activation of the prefrontal cortex.  Those working in cognitively-demanding occupations will likely struggle to maintain normative cognition whilst on hydroxyzine.  Cognitive deficits from hydroxyzine could cause decreased motivation/productivity, increase on-the-job errors, and lead to additional unwanted stress (as a result).

Constipation: A known side effect of hydroxyzine is constipation or inability to empty bowels.  If you become constipated while taking hydroxyzine, realize that it may subside with continued usage.  However, if the constipation is overwhelming, there may be several strategies you can utilize to decrease its severity such as by altering your diet and/or augmentation of a laxative.

Always talk to your doctor for the most trusted information in dealing with constipation as a side effect.  In some cases, a simple readjustment of your dosage may correct the constipation, whereas in other scenarios, a switch in medications may be necessary.  Realize that compared to most hydroxyzine side effects, constipation isn’t very common.

Depression: A reported side effect from some hydroxyzine users is depression or low mood.  There are a number of mechanisms by which hydroxyzine may cause depression in certain individuals including: decreased sympathetic activation (and catecholamine synthesis), altered neural activation, and neuroelectrical changes (e.g. fewer beta waves).  Hydroxyzine decreases arousal and CNS activation and is considered a CNS depressant.

If you become depressed while taking hydroxyzine, you are certainly not alone – this is a reported reaction.  Talk to your doctor about potential strategies for dealing with this depression as a result of your medication.  If you’ve been formally diagnosed with major depressive disorder (MDD), realize that hydroxyzine could exacerbate symptoms and potentiate your depressed outlook.

Diarrhea: Although a subset of hydroxyzine users may experience constipation, some experience the exact opposite – diarrhea.  Diarrhea is usually provoked by gastrointestinal irritation associated with ingestion of hydroxyzine.  Although some individuals may notice that diarrhea and/or loose bowels subside with continued hydroxyzine usage, others may report continuous, ongoing diarrhea.

One possible way to mitigate diarrhea is by taking an over-the-counter (OTC) agent such as Imodium.  That said, a simpler strategy that may prove efficacious in reducing diarrhea is to take hydroxyzine after a large meal.  By taking hydroxyzine with food or after a meal, gastrointestinal irritation may be reduced and/or subside as a result of the co-ingested food.

Dizziness: A commonly reported side effect with nearly every drug capable of altering neurotransmission is dizziness.  Some individuals may notice that while taking hydroxyzine, they feel a bit dizzier than usual.  For most hydroxyzine users, dizziness is of mild to moderate severity and is most severe within the first few days or weeks of administration.

In some cases, the dizziness subsides with continued hydroxyzine usage – likely due to the fact that neurophysiological processes have adapted to the drug.  Since the dizziness is not generally severe, most hydroxyzine users are able to put up with it as a side effect.  Additionally, reducing the dosage of hydroxyzine may prove effective in lessening the dizziness.

Drowsiness: The most common side effect (along with sleepiness) is drowsiness.  The drowsiness is likely a result of H1 histamine receptor inverse agonism.  Most antihistaminergics have a tendency to induce drowsiness, especially when taken at high doses.

In general, the greater the dosage of hydroxyzine you take, the more likely you are to become drowsy.  Realize that for certain individuals, the drowsiness is transient and subsides within a week or two of consistent hydroxyzine administration.  Since drowsiness can impair your ability to operate a motor vehicle and/or heavy machinery (at work), you may want to discuss it further with your doctor.

Dry mouth: The second most common side effect of hydroxyzine is dry mouth.  Clinical trials document that around 14% of all users will experience dry mouth, which can be uncomfortable.  It may feel as if the insides of your mouth are completely parched, and no matter how much water you drink, it doesn’t seem to fix the problem.

You may also feel as if your oral mucosa has transitioned from a state of optimal salivary lubrication to a complete desert.  When taking hydroxyzine, it is necessary to realize that it can interfere with your salivary glands’ ability to generate saliva.  As a result, your mouth becomes dry, feels raspy, and your breath may smell bad (from xerostomia-induced halitosis).

Fatigue: During treatment with hydroxyzine, you may feel as if someone hijacked your zest for life.  You may feel unusually lethargic and unable to summon adequate energy necessary to complete certain tasks throughout the day.  This fatigue is a common side effect of antihistaminergic medications such as hydroxyzine that function by decreasing CNS arousal.

Although hydroxyzine is an effective anxiolytic and can improve sleep quality, one tradeoff is that it may sap your energy.  Usually the fatigue associated with hydroxyzine is most severe during the first week of treatment.  After several weeks of treatment and/or dosage adjustments, fatigue is usually not severe enough as to impair a user’s ability to function.

Inability to concentrate: Taking hydroxyzine may impair your ability to concentrate.  Some research suggests that around 9% of hydroxyzine users report substantial difficulty concentrating as a result of treatment.  This side effect isn’t surprising when considering the fact that hydroxyzine is an antihistamine known to decrease CNS activity and arousal.

The degree to which you are unable to concentrate while taking hydroxyzine may depend on your dosage.  Individuals taking higher dosages of hydroxyzine will experience more potent antihistaminergic effects, leading to greater difficulty concentrating than low dose users.  If concentration problems are overwhelming, you may want to discuss other medications and/or a dosage reduction with your doctor.

Insomnia: Perhaps the most counterintuitive side effect of hydroxyzine is insomnia.  Insomnia is considered counterintuitive due to the fact that hydroxyzine is often effective as a treatment for insomnia and enhancing sleep quality.  If you take hydroxyzine and end up staying up all night, unable to fall asleep – you’re likely among the 9% of users that experience insomnia as a side effect.

Consider that insomnia could be a transient side effect that may subside with continued hydroxyzine usage.  Sometimes a user’s neurophysiology simply needs a few days or weeks to make neurochemical adjustments to accommodate hydroxyzine, and once these adjustments are made, side effects like insomnia may diminish or subside.  Users may want to consider that time of administration, dosage, and co-administered medications could influence likelihood of experiencing insomnia.

If the insomnia persists as you continue using hydroxyzine, you may want to discuss: your dosage and time of day at which you administer hydroxyzine – with your doctor.  Generally, high dose users who administer hydroxyzine at night have no difficulty falling asleep.  Nighttime administration at a moderate/high dose usually yields somnolence and facilitates sleep induction.

Low blood pressure: Some hydroxyzine users experience significant reductions in blood pressure to the extent of hypotension.  Hypotension is characterized by dizziness, lightheadedness, and in more extreme cases – fainting.  If you have a history of low blood pressure or suspect that hydroxyzine is causing hypotension, you may want to monitor your blood pressure on a regular basis.

The degree to which your blood pressure drops while taking hydroxyzine may be dependent upon the dosage that you’re taking.  Since higher doses are most likely to induce the greatest degree CNS depression, high-dose users may be most likely to experience hypotension (as compared to low-dose users).

Nausea: Though uncommon, some individuals may become nauseated as a result of taking hydroxyzine.  Nausea as a side effect of hydroxyzine may be caused by numerous factors including: gastrointestinal irritation, taking it on an empty stomach (increasing likelihood of GI distress), administration with another medication, etc.  If the nausea is caused by gastrointestinal irritation, a user may benefit from taking hydroxyzine after a meal and/or along with an over-the-counter medication for GI irritation.

Prolonged erections: A lesser common, relatively unexpected adverse effect associated with hydroxyzine usage is prolonged penile erections.  One case report documented a particular individual who experienced sustained erections each time he took hydroxyzine.  That said, it is important to note that other studies have not documented prolonged erections as a common occurrence, therefore it should be considered a rare, adverse reaction.

Although prolonged erections may be perceived as favorable among a subset of individuals that have difficulty sustaining an erection of adequate duration to satisfy their partners, most hydroxyzine users won’t want an uncontrollable erection spanning for hours.  Researchers believe that the propensity of hydroxyzine to promote erections stems from its metabolite known as norchlorcyclizine.  Norchlorcyclizine is similar in chemical structure to m-chlorophenylpiperazine, a metabolite of the atypical antidepressant trazodone that has also been known to induce erections.

  • Source: http://www.ncbi.nlm.nih.gov/pubmed/7969858

Skin rash or redness: Though the antihistaminergic properties of hydroxyzine can provide substantial relief to an individuals experiencing itchy skin from an allergic reaction, some users may actually develop a skin rash from hydroxyzine.  Evidence suggests that a small percentage of hydroxyzine users will develop a maculopapular skin rash.  Maculopapular rashes are characterized by patches of skin redness with small bumps.

Although the hydroxyzine-induced maculopapular rash is unlikely to be itchy, it is an obvious cause of concern.  Seek immediate medical attention if you experience a rash after taking hydroxyzine.

  • Source: http://www.ncbi.nlm.nih.gov/pubmed/9145264

Sleepiness: Approximately 28% of hydroxyzine users will experience sleepiness as a side effect.  Although some sleepiness may be manageable, intense sleepiness may be considered unwelcome and difficult to manage.  If you feel as if you want to sleep your entire day away while taking hydroxyzine, you should know that the sleepiness may be transient.

Research indicates that sleepiness as a side effect was generally most severe within the first week of regular hydroxyzine administration.  Thereafter, sleepiness decreased and alertness/arousal seemed to have normalized.  Obviously if the sleepiness is persistent and fails to subside after several weeks of treatment, you may need to discuss reducing your dosage with a doctor or utilizing some sort of stimulatory adjunct to maintain wakefulness.

Typically, the higher the dosage of hydroxyzine you’re taking, the greater the likelihood you are to experience sleepiness.  Higher doses exert a more substantial sedating effect via H1 receptor inverse agonism than lower ones.  Additionally, it is plausible to consider that 5-HT2A receptor antagonism may also play a role in hydroxyzine’s propensity to induce sleepiness.

Stomach aches: Gastrointestinal distress and upset stomach can occur while taking hydroxyzine.  As a result of this distress, some hydroxyzine users may notice stomach aches and/or cramps.  If you’re experiencing stomach aches while taking hydroxyzine, it may be beneficial to talk to your doctor about dividing a large single dosage up into smaller dosages that are less likely to provoke upset stomach.

Another possible way to reduce the likelihood of stomach aches is to take hydroxyzine with food or after a large meal.  Sometimes taking hydroxyzine on an empty stomach increases gastrointestinal irritation and causes pains or aches.  The severity of stomach aches resulting from hydroxyzine is usually considered mild.

Tinnitus: Many drugs can cause tinnitus or “ringing in the ears,” including hydroxyzine.  It is unknown as to whether this side effect is a result of ototoxicity or simply transient adjustments in auditory processing.  That said, if you notice that your ears start ringing or buzzing constantly while taking hydroxyzine, it may be smart to consider other options and discuss this side effect with your doctor.

Tinnitus is a reaction that should always be taken seriously due to the fact that it could become permanent.  Usually if the tinnitus is noticed immediately and hydroxyzine is discontinued, it won’t become permanent.  Realize that compared to most other hydroxyzine side effects, tinnitus isn’t very common.  Lower doses may decrease likelihood of tinnitus development.

Tiredness: Many individuals taking hydroxyzine will feel excessively tired, unable to get out of bed in the morning.  The tiredness may be most significant early in the morning, but may linger throughout the day.  If you’re struggling to stay alert, you may want to counteract the increase in tiredness with some caffeine and/or a low-grade, legal stimulatory agent.

Since tiredness typically goes hand-in-hand with sleepiness, they may be considered analogous side effects.  However, not everyone who necessarily feels tired automatically feels sleepy.  Therefore, it may be best to list tiredness and sleepiness as separately occurring reactions to ingestion of hydroxyzine.

Tremors: A small percentage of hydroxyzine users may experience involuntary, uncontrollable muscle movements in the form of tremors or spasms.  If you find yourself shaking or exhibiting tremors after taking hydroxyzine, immediately contacting a medical professional is advised.  It should be noted that tremors induced via hydroxyzine are thought to occur most often among those taking high dosages.

With this knowledge, we can conclude that an obvious way to reduce the likelihood of tremors is to take a minimalist approach to dosing (e.g. don’t take more than necessary for therapeutic benefit).  Tremors are most likely to occur among recreational hydroxyzine users, cases of overdose, and/or anyone ingesting larger amounts than their nervous system can tolerate.  Those prescribed supratherapeutic dosages should be most cognizant of this side effect.

Weight gain: It is estimated that around 12% of all hydroxyzine users will gain some weight.  It is unclear as to exactly what spurs the weight gain, but there are numerous potential causes to consider.  Since hydroxyzine is a depressant, it may: slow a user’s basal metabolic rate and/or promote lethargy or laziness.  Rather than going to the gym for your normal workout, you may feel like sitting on the couch watching TV instead because the hydroxyzine makes you too drowsy.

A subset of hydroxyzine users may also experience an increase in appetite and/or food cravings (e.g. carbohydrates).  Couple the increased appetite and caloric intake with decreased physical activity, and some users will notice weight gain.  Keep in mind that the weight gain experienced while taking hydroxyzine is unlikely to be significant and should be quickly lost upon discontinuation.

Note: The hydroxyzine side effect listed above may not occur in every single user.  Also, there may be additional side effects that occur in a subset of hydroxyzine users that were not reported here.  If you have any questions regarding hydroxyzine’s side effect profile, contact a medical professional.

Variables that influence Hydroxyzine side effects & adverse reactions

If you experience side effects from hydroxyzine, it may be helpful to understand the variables that influence their occurrence.  Why can one person tolerate hydroxyzine perfectly fine, yet another may report excessive drowsiness, inability to focus, and weight gain?  Variables that may predict the severity and number of hydroxyzine side effects that you experience include: daily dosage, co-ingested drugs, term of administration, and dosing time.

  1. Dosage (Low vs. High)

The dosage of hydroxyzine taken by a user is generally the most predictive of severity and number of side effects he/she is likely to experience.  Logically, those taking lower dosages are of lesser likelihood to experience side effects than those taking higher dosages.  This is due to the fact that the lower the dosage of hydroxyzine ingested, the lesser the neurophysiologic influence exhibited by the drug.

At higher dosages, a greater quantity of the hydroxyzine chemical necessitates absorption, metabolism, and distribution – leading to more significant neurophysiologic modification and ultimately, more side effects.  In fact, the literature implies that certain side effects (e.g. tremors) only often occur among those taking high dosages.  If you’re experiencing many side effects while taking hydroxyzine, it may be due to the substantial antihistaminergic effect accompanying high doses.

  1. Duration of Administration

Research indicates that certain side effects associated with hydroxyzine are transient, particularly the drowsiness/sleepiness.  In other words, these side effects may emerge over a short-term (e.g. the first week or two of treatment), but then subside with continued hydroxyzine administration.  If you’ve only taken hydroxyzine for a short-duration, it’s necessary to consider that some side effects may diminish within the next several weeks.

Typically, those that have been using hydroxyzine for several months are well-adapted to the drug and less likely to experience overwhelming side effects.  That said, it is possible that some side effects may emerge over a long-term that didn’t previously occur over a short-term.  Long-term side effects may manifest from dosing changes (especially increases) and/or neurophysiologic alterations.

  1. Co-ingested substances

Co-administration of other substances along with hydroxyzine such as pharmaceutical drugs and/or supplements may influence the side effects that you experience.  In some cases, side effects perceived to stem from hydroxyzine are really a result of the other drug(s) or supplement(s) that you’ve administered.  In other cases, side effects you’re experiencing may be a result of an interaction between hydroxyzine and another substance.

If you’re taking hydroxyzine along with an array of supplements and/or drugs, it is necessary to first rule out contraindications with a medical professional.  Thereafter, it may be worth investigating potential pharmacokinetic (e.g. CYP450 enzyme) and pharmacodynamic (e.g. potentiation of H1 inverse agonism) interactions.  An increased propensity of side effects should be expected among those utilizing other substances with hydroxyzine.

That said, it should also be considered that certain co-ingested substances may actually decrease likelihood of certain side effects.  For example, someone taking a prescription psychostimulant such as Adderall may not experience drowsiness nor the fatigue that often occurs among hydroxyzine users.  Conversely, someone taking another prescription depressant is likely to exhibit an exacerbation of certain side effects.

  1. Hepatic Metabolism (CYP2D6)

Following oral administration of hydroxyzine, it undergoes hepatic metabolism primarily facilitated via CYP2D6 (cytochrome P450 2D6) isoenzymes.  Since the gene associated with CYP2D6 is highly polymorphic, the side effects (and efficacy of hydroxyzine) may be a result of a user’s specific CYP2D6 haplotype.  Approximately 5-10% of the population exhibits little or no CYP2D6 isoenzyme function and therefore may be unable to efficiently metabolize hydroxyzine.

Inefficient hydroxyzine metabolism as a result of poor CYP2D6 function may lead to high plasma concentrations of the drug and increase likelihood of side effects.  Intermediate CYP2D6 metabolizers, characterized by slightly more CYP2D6 function than poor metabolizers, are also likely to experience unwanted side effects.  Intermediate CYP2D6 metabolism is thought to affect approximately 10% of the population.

Over 70% of the population (most users) will be considered extensive metabolizers, characterized by normative expression of CYP2D6 isoenzymes.  Extensive metabolizers can experience side effects, but the intensity and/or severity are likely to be reduced compared to poor or intermediate metabolizers.  The subset of users considered CYP2D6 ultrarapid metabolizers may not experience as many side effects from standard doses, but may also fail to derive therapeutic benefit from hydroxyzine.

  1. Dosing schedule

Many people fail to consider that the time of day they take hydroxyzine may influence the side effects experienced and/or consciously noticed.  Someone taking hydroxyzine in the morning may report feeling fatigued throughout the day, drowsy, cognitively impaired, and uncoordinated.  These side effects may be frustrating and more obvious when that individual is struggling to finish his/her occupational or schoolwork in a timely, productive manner.

However, if the hypothetical aforestated individual switched his/her dosing regimen to late afternoon and/or nighttime, side effects may be less noticeable and/or bothersome.  The human body manufactures different hormones, chemicals, etc. – to match the time of day.  It could be that side effects of hydroxyzine are offset by endogenously manufactured hormones/chemicals based on time of day.

On the other hand, it could be that users taking hydroxyzine later in the day or at night may simply sleep through their side effects.  If they’re sleeping through the side effects, they aren’t noticed and therefore may not be problematic.  There is some evidence to suggest that administration of hydroxyzine later in the day (e.g. afternoon or night) may be an effective side effect mitigation/reduction strategy.

Hydroxyzine: Do the benefits outweigh the side effects?

If you’ve been taking hydroxyzine, it is necessary to continuously evaluate whether the therapeutic benefits you’ve attained outweigh the side effects you’re experiencing.  Among individuals that take hydroxyzine for weeks and experience zero therapeutic relief, yet also experience a host of unwanted side effects – discontinuation is likely a smart option.  Similarly, those that haven’t experienced any side effects, but also haven’t reaped any benefit from hydroxyzine may want to discontinue in pursuit of another option.

It makes no sense to continue taking a medication if it has no therapeutic value and/or the side effects outweigh the benefits.  That said, a majority of hydroxyzine users will experience a blending of therapeutic benefit with side effects.  For example, hydroxyzine may significantly attenuate symptoms of generalized anxiety disorder, but may also provoke feel brain fog and/or drowsiness throughout the day as a result of antihistaminergic effects.

If the drowsiness and/or brain fog is severe enough to jeopardize occupational performance and/or higher education, hydroxyzine may necessitate discontinuation.  However, if the brain fog is mild and doesn’t significantly impair your performance, all while significantly reducing your anxiety – staying the course of treatment is a logical choice.  It may help to objectively track the therapeutic benefits and side effects with cognitive batteries and/or anxiety scales (or whatever condition you’re treating).

Subjectively, you may want to use a journal software to document how you’ve felt each day since using hydroxyzine.  Discuss any concerns regarding hydroxyzine side effects with your doctor and determine whether there are any potential solutions.  Realize that ultimately it is up to you to evaluate whether the therapeutic value outweighs the unwanted side effects and to decide whether hydroxyzine is worth continuing.

Possible ways to reduce Hydroxyzine side effects

If you’re taking hydroxyzine and are struggling with its side effects, you may want to consider some potential side effect mitigation strategies.  Prior to implementing any of these strategies, the safety and alleged efficacy should be discussed with a medical professional.  That said, strategies such as: dosage adjustments, dosing schedule modifications, and taking hydroxyzine with food (rather than an empty stomach) – may prove beneficial.

  1. Dosage reduction

Regardless of the dose you’re taking, it may be necessary that the dosing is simply too high for your neurophysiology to handle.  The greater the dosage you take, especially all-at-once (rather than divided doses throughout the day), the more substantial the side effects are likely to be.  Higher doses exert greater neurophysiologic changes and will pack a more substantial antihistaminergic punch than lower ones.

If you feel as if you’ve been prescribed too high of a dose, this may be reason for your side effects.  It may be worth talking to your doctor about lowering your daily hydroxyzine intake to find the minimal effective dose.  A minimal effective dose is considered just enough to provide symptomatic relief, but zero excess.

Since many users likely administer a larger amount of hydroxyzine than necessary for symptomatic relief, these individuals may experience side effects that could’ve otherwise been avoided.  For those that haven’t yet started taking hydroxyzine, it may be worth talking to your doctor about starting at very small “baby” doses and gradually titrating your way up to find the minimal effective amount.

  1. Revise dosing schedule

Some individuals may take hydroxyzine in the morning, others take it mid-day, and another subset of users may take it at night.  Assuming you’re already taking the minimal effective dose of hydroxyzine and are still experiencing side effects, you may want to revise your dosing schedule with the help of your doctor.  If you’re experiencing noticeable side effects when taking hydroxyzine in the morning, shifting to nighttime administration may be of significant benefit.

A study entitled “Objective antihistamine side effects are mitigated by evening dosing of hydroxyzine” noted that side effects of hydroxyzine were decreased if administered at bedtime.  Researchers of the study found that taking hydroxyzine at night also decreased the adverse effect of prolonged reaction times.  Authors concluded that certain adverse effects, especially impairment of psychomotor performance can be mitigated with creative dosing schedules (Source: http://www.ncbi.nlm.nih.gov/pubmed/1683192).

Your doctor may want you to try hydroxyzine in the morning, then the next day in the afternoon, and the following day at bedtime.  In each scenario, you’ll document and report side effects to determine which time of day (subjectively) prompted the least side effects.  Whichever dosing time is associated with the fewest side effects could be the optimal one for your biology.

Since many people don’t experiment with the time of day a drug is taken, a simple adjustment may make a huge difference in regards to side effect mitigation.  Similarly, experimenting with the frequency of hydroxyzine administration such as taking one large dose per day, two smaller doses per day (b.i.d.), or three tiny doses per day (t.i.d.) – could make a difference.  Some people experience less side effects with extremely tiny doses, while others function better with one large dose.

  1. Take with food

Medical literature implies hydroxyzine can be taken with food or on an empty stomach.  Although taking the drug with food or without may not affect everyone, some people experience more side effects when taking it on an empty stomach.  Side effects stemming from gastrointestinal distress such as stomach aches, constipation, or diarrhea – may be a result of taking the drug without any food.

A strategy that may prove beneficial for those with GI distress is to only take hydroxyzine after they’ve eaten some food.  If you want to get more advanced, you could experiment with different types of food groups (e.g. high fat, high protein, high carb) to determine which best attenuates side effects.  Food may slightly slow the absorption of hydroxyzine, leading to a gradual increase in plasma concentrations rather than a quicker spike that may occur with an empty stomach.

  1. Avoid unnecessary drugs and supplements

Another way to decrease the likelihood of side effects associated with taking hydroxyzine is to avoid unnecessary drugs and supplements.  Taking any unnecessary pharmaceutical or supplemental agent with hydroxyzine increases risk of contraindications and interaction effects.  Individuals that are taking hydroxyzine as part of a supplement stack or pharmaceutical cocktail may want to work with their doctor to cut out any unnecessary agents.  Sticking to standalone hydroxyzine may significantly decrease occurrence of side effects.

  1. Add another drug or supplement

Although eliminating unnecessary drugs and supplements may decrease the occurrence of side effects, sometimes it won’t provide any benefit.  Additionally, some individuals aren’t taking any additional drugs or supplements with hydroxyzine in the first place.  For this reason, it may be necessary to discuss the most troubling side effects with a medical professional and determine what other substances can be taken to offset these effects.

For example, someone experiencing severe brain fog and lethargy may benefit from a low dose stimulatory agent; regardless of whether pharmaceutical or supplemental.  Obviously the particular drug or supplement added to hydroxyzine will need to be carefully selected as to avoid contraindications and symptomatic exacerbation (of the condition being treated with hydroxyzine).

  1. Continue using

Several of the most prominent side effects associated with hydroxyzine including: drowsiness, fatigue, and sleepiness – are often transient.  Evidence from research suggests that they are usually most severe during the first week of treatment, and generally diminish in severity over time.  If you’re a relatively new hydroxyzine user, it may be worth simply staying the course of treatment for awhile until you’ve fully adjusted to the drug.

Sometimes it takes a couple of weeks for your neurophysiology to acclimate itself to hydroxyzine.  After neurophysiologic adjustments have taken place, and you’ve used hydroxyzine for several weeks, you may notice that initially troubling side effects subside or become more manageable.

Have you experienced Hydroxyzine side effects?

If you’ve taken hydroxyzine, feel free to share any side effects you experienced in the comments section below.  Discuss the most noticeable side effects that you experienced and their respective severities (on a scale from 1 to 10).  To help others get a better idea of your situation, mention details such as: reason for taking hydroxyzine, your dosage, time(s) of day taken, cumulative duration of usage, CYP2D6 metabolism, and whether you utilize any other medications (or supplements) with it.

Realize that nearly every pharmaceutical drug (and even most dietary supplements) have side effects.  When it comes to hydroxyzine, the most common side effects are: sleepiness and dry mouth (as a result of the antihistaminergic effect).  If the side effects from hydroxyzine are overwhelming and compromising your quality of life, talk to a medical professional about discontinuation and/or switching to another medication.

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13 thoughts on “Hydroxyzine Side Effects & Adverse Reactions (List)”

  1. I have only been taking Hydroxyzine 25 mg. tablets for one and a half days—3 times a day, but have had diarrhea and feel sleepy. It was prescribed for my itchy skin, a symptom I developed on a recent cruise. I hope that as I take it, the itch and sleepiness will both disappear.

  2. I went to urgent care with severe fight-or-flight high cortisol/adrenaline anxiety, induced by a sudden drop in estrogen (after 10 years in menopause, becoming a vegetarian brought back perimenopause). I was taking .5 klonopin interspersed with benadryl every 2 hours and it was nowhere near doing the job.

    Then I was given a prescription for Atarax and took one 25 mg tablet. Wasn’t surprised at zombie effect (especially as all the klonopin suddenly hit) but for me it was like five minutes felt like 30, as I lay in a waiting room, feeling removed from the shooting of adrenaline going on in my body.

    Perceived as a super long day, but a lifesaver. The next day was a calm one and it had been over 2 months since I had a full day that was calm instead of continuously fight-or-flight with morning cortisol from morning until the last few hours of the day, despite my use of klonopin, which had previously prevented such things, but which seemed hostile to the hormone problems I was having of which I was as yet unaware.

    I haven’t tested it yet, but it makes me wonder if my problem with turning off the adrenaline might be jump-started (I’ve had these attacks recur several times now since starting bio-identical hormone replacement therapy (the progesterone is wonderful for calming cortisol/adrenaline and is something both females and males should consider if they have this problem).

    Only tonight did I realize that it wasn’t so much something I have to live with when my estrogen drops, as my usual problem of turning off the cortisol/adrenaline once it’s been activated. So I imagine I’ll be testing this sometime when I can get some people to help me pass the six hours in what is subjectively many more.

  3. My neurologist put me on it because I was having a breakdown and the hydroxyzine calmed my nerves. I also take trazodone to sleep – had not been having night sweats or hot flashes. I try to manage my diet with shakes and eating healthy.

    I tried to back off and stop. Even though it caused the “fog” I felt my stress level get better. Last night I woke up with the worst night sweats ever. I am also premenopausal, but have been doing great keeping them in check. I take 300 mg 1-3 times a day.

  4. I have only been on hydroxyzine (atarax) for a bit more than a week and I have not been sleeping well despite taking Trazodone for sleep and I have been having night sweats. The worst thing I notice is a significant increase in appetite.

    I am always hungry now (wasn’t before) and I am craving a lot of sugar or really salty stuff. I am hungry even after eating a nice sized meal within 30 minutes or less. I don’t see a big difference in my anxiety, thinking about discontinuing before I gain too much weight.

  5. Has anyone had what I would call a “guillotine slamming sound” in the head from hydroxyzine? Is there some other way to describe it? My doctor doesn’t know what could be causing it.

  6. Severe suicidal depression and weight gain. Need to get off. Taking 50mg/ night. Doctor originally had me on 75mg daily and I was a zombie. I am fatigued. I already have depression.

    Why would they give this to me? My depression is worse and I am fat. Also take Klonopin and lexapro. I want off all. Money maker for them. Destroying my health and my life. God help me get off.

  7. I have taken Hydroxyzine for 2 years now and trying to get off slowly. In the last four months I have gone from my highest dose of 20 mg to 10 mg. I am surprised at how much such a low dose once a day was able to help anxiety and insomnia. Now at 10 mg I am really struggling to sleep.

    I feel like I have definitely gained weight with an increased appetite along with increased dizziness throughout the last 2 years. I want to be off this medicine and will continue to slowly decline.

    That being said, it was a godsend when I started taking it and has worked wonders for my anxiety and insomnia! I am 29, it’s time to try to be medicine free.

  8. I have taken 25-50 mg nightly for over 5 years. I developed tinnitus last summer, started having UTIs quite often (having had only 1 bout in my life previously to taking hydroxyzine), and most recently I have started to experience a fullness in my ears.

    I did not even think to attributing it to hydroxyzine but after googling and finding out that people 60+ taking hydroxyzine for 2-5 years can develop tinnitus. I’m going to talk to my NP and stop taking it. Hopefully the tinnitus will resolve itself, plus less or no more UTIs, and not having my ears plug up.

  9. Taking .25 mg of Hydroxyzine for itchy skin. Noticed that it made me quite sleepy at first within an hour of taking it. Started taking it right before bed. Have noticed a tightening of chest and heart palpitations which I have never experienced before. I am a healthy, active person in my early 40’s.

    I have also experienced a gradual weight gain and feeling like I am retaining water and just bloated. I have ramped up my fitness routine to include more running (30 minutes a day) but have not noticed that it is helping with my weight. Also experiencing some constipation although drinking plenty of water where I have never had that problem before.

  10. I have been on Hydroxyzine .25mg. for 6 months. Prescribed for sleep and anxiety. Never have had a weight problem. After taking this medication for a few months, I have a appetite increase and have gained 15 lbs. along with other side effects and symptoms including, heart palpitations,
    Stomach aches, increased stomach gas, reflux, tinnitus, skin rash, spasms.

    Benefits of this medicine, I don’t have anxiety and I can sleep fairly well. I had been on Xanax .25mg for a long period of time for anxiety and sleep, I prefer the calmer feeling I have on the Xanax for anxiety and sleep without all the side effect that I’m having on the Hydroxyzine.

  11. Minimally helped anxiety as I have both anxiety & depression. I think it made depression worse. Terrible insomnia, chills & hot flashes, bad headache & congestion making it feel like I couldn’t breahe. Not worth it for me.


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