How Long does Hydroxyzine Stay in Your System?

By Arielle Mitton
Medically reviewed checkmarkMedically reviewed
June 21, 2022

Hydroxyzine is an antihistamine that is frequently used for conditions like anxiety or allergic reactions.

If you are taking hydroxyzine, you may wonder how long it will take to notice beneficial effects as well as how long hydroxyzine actually stays in your system.

In this article, we’ll explore how quickly hydroxyzine works and common side effects.

I’ll also go over possible alternative medications and how to know when you should see a doctor.

How Long Does Hydroxyzine Stay in Your System

Hydroxyzine is prescribed for allergic reactions or symptoms associated with allergies that are driven by histamine reactions (such as hives and itchy skin).

Anxiety, while not an allergic reaction, may also be driven by histamine receptors in the central nervous system (CNS).

Because of this common link, hydroxyzine may be prescribed and used effectively for both conditions.

A common side effect of hydroxyzine is drowsiness because of the way that it impacts the brain.

For acute allergy reactions or anxiety, hydroxyzine can be effective because it takes effect quickly.

Hydroxyzine usually provides symptom relief within 15-30 minutes of taking it.

The half-life is between 16-24 hours, but it may be shorter in children and longer in older adults or people with impaired kidney or liver function.

Because the effects peak at 2 hours, hydroxyzine may be prescribed to be taken 3-4 times per day, or every 6-8 hours. Always follow your prescription instructions.

If you stop taking hydroxyzine, the elimination half-life refers to how long it takes for the medication circulating in your body to be reduced by half.

In the case of hydroxyzine, it has a longer-lasting effect than diphenhydramine (Benadryl), another drug in the same class, which has a half-life of 3-9 hours.

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How Quickly Does Hydroxyzine Start Working?

Depending on the dosage you were prescribed and the reason you are taking hydroxyzine, you may notice relief within 15-30 minutes.

Common Dosage Guide

Hydroxyzine is available by prescription as a generic drug, or as brand name drugs Vistaril or Atarax.

Dosage depends on the reason it was prescribed, symptoms, and other health conditions.

Your healthcare provider will use the lowest effective dosage to minimize side effects, such as drowsiness.

  • Skin reactions or allergies: typically 25 mg, 3-4 times per day
  • Anxiety symptoms or generalized anxiety disorder: typically 50-100 mg, up to 4 times per day

Hydroxyzine Side Effects

Hydroxyzine is associated with some common side effects, like many prescription drugs.

In some cases, they can be serious. Patients should report any side effects or reactions to a healthcare provider right away.

Always let your prescriber and pharmacist know if you take any other medicines, OTC drugs, or supplements.

This can help prevent avoidable interactions.

Common Side Effects

Hydroxyzine may cause some common mild side effects.

The higher the dosage, the more noticeable they may be.

They include:

More Serious Side Effects

Hydroxyzine can also cause some serious side effects.

This is especially true if it is taken incorrectly or taken with certain medications.

Hydroxyzine is not safe for certain health conditions.

Be sure that your healthcare provider and pharmacist are aware of your medical history and anything that you take, including:

  • Other medicines
  • Over-the-counter drugs
  • Supplements, vitamins, and herbs

If you experience any severe side effects, discontinue use right away and seek medical attention.

The following are not a full list of severe side effects associated with hydroxyzine:

  • Rash
  • Skin redness
  • Pus-filled or blister-like sores
  • Seizures
  • Unintentional tremoring, trembling, or shaking
  • Fever

Older people may be at higher risk for side effects, as well as those who have liver or kidney disorders, or certain heart conditions.

Hydroxyzine overdose is possible if you take more than is prescribed.

This can be serious and life-threatening. If you accidentally or intentionally take too much hydroxyzine, call 911 immediately.

If you’re having a mental health emergency, call 911 or go to the nearest emergency room. You can also get free 24/7 support from a suicide and crisis expert by calling or texting 988. If you’d prefer to chat online, you can chat with a suicide and crisis expert by visiting the Lifeline Chat.

Hydroxyzine Withdrawal Symptoms

Hydroxyzine is not associated with common withdrawal symptoms.

People who take it long-term or are used to its benefits may notice more symptoms when discontinuing.

Unless you have a severe allergic reaction, do not discontinue medication without first consulting your healthcare provider.

Is Hydroxyzine Habit-Forming?

Hydroxyzine is an antihistamine and is not a controlled substance. It is not habit-forming.

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Hydroxyzine Alternatives

In some cases, hydroxyzine may not be indicated due to certain medical conditions or other prescriptions a patient already takes.

Some possible alternatives for hydroxyzine include:

  • For allergic reactions: Diphenhydramine (Benadryl), desloratadine (Clarinex), fexofenadine (Allegra), or loratadine (Claritin)
  • For anxiety or panic attacks: Alprazolam (Xanax)

Alprazolam is a controlled substance. It can be habit-forming and addictive.

Hydroxyzine is often a preferred anxiety treatment, but Xanax may be preferable if the patient has medical conditions that are not compatible with hydroxyzine. 

When to See a Doctor

See a healthcare provider for medical advice if you have questions about hydroxyzine or any of the conditions it may treat.

Your healthcare provider may recommend hydroxyzine for conditions or symptoms associated with high histamine levels, such as allergies.

They may also suggest it for acute anxiety episodes or generalized anxiety disorder.

Whether your quality of life is impacted by allergies or anxiety, your healthcare provider will help formulate a plan to address your symptoms.

Hydroxyzine, other medications, or lifestyle suggestions may all help to improve how you feel.

How K Health Can Help

Think you might need a prescription for Vistaril (hydroxyzine)?

K Health has clinicians standing by 24/7 to evaluate your symptoms and determine if hydroxyzine is right for you.

Get started with our free assessment, which will tell you in minutes if treatment could be a good fit. If yes, we’ll connect you right to a clinician who can prescribe medication and have it shipped right to your door.

Frequently Asked Questions

How long does hydroxyzine stay in your system for anxiety?
Hydroxyzine starts working within 15-30 minutes, and reaches its peak level of effectiveness around 2 hours after it is taken. But the half-life is longer, and it may stay in your system for 16-24 hours. But the noticeable anti-anxiety benefits may wear off sooner than that which is why your prescriber may suggest taking it 3-4 times per day. Always follow the instructions of your prescription. Taking hydroxyzine incorrectly, or at higher doses, can lead to serious side effects.
Does hydroxyzine make you tired the next day?
How hydroxyzine affects you depends on your dosage and the time of day that you take it. Drowsiness is a common side effect. If you take it before bed, there is a chance that it could still leave you feeling drowsy the next morning. However, your medical provider will try to prescribe the lowest effective dose to minimize side effects that linger or affect your quality of life.
Does hydroxyzine have withdrawal symptoms?
Hydroxyzine is not habit-forming or addictive. You do not have to taper a dose before stopping, but you should still work with your medical provider if you want to stop taking hydroxyzine. You may notice symptoms when you stop taking hydroxyzine, especially if you were taking it for acute anxiety or histamine-related allergy symptoms.
K Health articles are all written and reviewed by MDs, PhDs, NPs, or PharmDs and are for informational purposes only. This information does not constitute and should not be relied on for professional medical advice. Always talk to your doctor about the risks and benefits of any treatment.

Arielle Mitton

Dr. Mitton is a board certified internal medicine physician with over 6 years of experience in urgent care and additional training in geriatric medicine. She completed her trainings at Mount Sinai Hospital and UCLA. She is on the board of the Hyperemesis Research Foundation to help women suffering from hyperemesis gravidarum.