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What is hydroxyzine?

Hydroxyzine belongs to a class of drugs called antihistamines. It is sold as a generic medication and under the brand name Vistaril.

It works by blocking the effects of a chemical called histamine, which is produced during an allergic reaction or a viral infection such as the common cold.

Hydroxyzine also works by lessening certain activities in the brain. It’s unclear exactly how hydroxyzine works in the brain, but medical experts believe the drug may suppress activity in specific regions of the subcortical of the central nervous system.

The drug is related to over-the-counter antihistamines like Zyrtec and Benadryl, but you need a prescription to use hydroxyzine.

Hydroxyzine comes in the form of a tablet, capsule, syrup, oral suspension, and injectable solution.

The drug was first approved in 1956 by the US Food and Drug Administration (FDA).

What is hydroxyzine used to treat?

You can take hydroxyzine to treat allergy symptoms and colds, such as a runny nose and itchy or watery eyes. It also treats skin rash and relieves itching caused by allergic skin conditions like contact dermatitis, atopic dermatitis (eczema), and hives.

Other uses of hydroxyzine include:

  • Treatment for anxiety and tension

  • Sedative before or after general anesthesia for surgery

  • Treatment for nausea/vomiting

How do you take hydroxyzine?

Take hydroxyzine as prescribed by your doctor. Don’t start or stop taking the medication without proper consultation, and don’t adjust the dosage on your own.

Do not break or chew the capsule. Take it whole, then drink water.

Shake the liquid formulation well and use a measuring spoon, medicinal cup, or oral syringe when measuring your dosage. If the package doesn’t include these measuring tools, pharmacy-bought measuring tools are suitable.

Hydroxyzine is prescribed to be taken daily at regular intervals, usually three to four times a day. In some cases, it is prescribed to be taken when needed.

Dosage for hydroxyzine depends on the severity of your medical condition, age, and response to treatment. Dosages for children are dependent on their weight.

Here are the standard oral doses for adults¹ and children¹ for treating different medical conditions with hydroxyzine:

Pruritus (itchy skin) and atopic dermatitis (eczema)

  • 25mg three to four times daily (adults)

  • 50mg daily divided into separate doses (children younger than six years)

  • 50–100mg daily divided into separate doses (children older than six years)


  • 50–100mg four times a day

  • 50mg daily divided into separate doses (children younger than six years)

  • 50–100mg daily divided into separate doses (children older than six years)

Remember to always follow your doctor’s prescription when taking hydroxyzine. Your doctor will prescribe the right dose for you and your condition.

Seeing results

Hydroxyzine is quick to take effect. You might notice your symptoms improving within as little as 30 minutes.²

If you’re taking hydroxyzine to treat anxiety, you may notice improvements within hours³ of taking the drug.

Potential side effects of hydroxyzine

Most side effects of hydroxyzine are unserious and eventually wear off on their own. Some of these side effects include:

  • Fatigue

  • Nausea

  • Dizziness

  • Muscle tremors

  • Muscle weakness

  • Confusion

  • Dry mouth

  • Constipation

  • Low blood pressure (more serious if you have hypotension)

Inform your doctor if you develop any of these side effects, especially if you notice them worsening or they don’t go away on their own.

Serious side effects

Stop using hydroxyzine and seek urgent medical help if you experience:

  • Seizures

  • Trembling or shaking

Hydroxyzine may also cause a severe allergic skin reaction. Symptoms include:

  • Blister-like lesions filled with pus

  • Swelling and redness

  • Fever

  • Rash

Taking hydroxyzine can be dangerous if you have other health conditions, such as heart problems, hypotension, dementia, or liver or kidney problems. Hydroxyzine can worsen existing health conditions or cause more serious side effects, which could be life-threatening.

Long-term use of hydroxyzine

Hydroxyzine is a short-term medication only and is not recommended for long-term use. However, using the drug for a long period of time is not thought to be harmful.

Missed doses

Take a missed dose as soon as you remember. If it’s nearly time for your next dose, skip the missed dose and resume your regular dosing schedule. Don’t take two doses at once to make up for the one you missed.


Symptoms of hydroxyzine overdose include:

  • Severe drowsiness

  • Headache

  • Rapid heartbeat

  • Abnormal heart rhythm

  • Slow reflexes

  • Impaired coordination

  • Seizures

  • Coma

  • Difficulty urinating

Seek urgent medical care if you suspect you or someone else has taken too much hydroxyzine.

What to discuss with your doctor before taking hydroxyzine

Before you start taking hydroxyzine, speak to your doctor about the following things:

  • Any medication allergies you have. Tell your doctor if you have ever had an allergic reaction to hydroxyzine.

  • Other medications you are currently taking (over-the-counter or prescription).

  • Herbal medicines or nutritional supplements you are currently taking or plan to take.

  • Other health conditions. You must tell your doctor if you have asthma, high blood pressure, kidney problems, seizures, stomach problems, glaucoma, dementia, or a heart condition known as a prolonged QT interval.

  • Any other non-medical treatment you are undergoing.

  • Pregnancy and breastfeeding. Tell your doctor if you’re pregnant or planning to become pregnant. They should also know if you are currently breastfeeding.

Stopping hydroxyzine

Take hydroxyzine as prescribed by your doctor. Do not stop taking hydroxyzine if you are not advised to do so. Suddenly stopping the use of hydroxyzine can cause symptoms to return or worsen, and decrease the overall effectiveness of the medication.

Hydroxyzine and pregnancy

Hydroxyzine is an FDA pregnancy category C⁴ drug. This means animal studies have shown adverse effects during pregnancy, but there is insufficient human research.

Taking hydroxyzine during pregnancy is thought to be safe, but studies are limited and you should speak to your doctor about the potential risks and benefits. Your doctor may advise against taking hydroxyzine during the first trimester.

Taking hydroxyzine while breastfeeding is not recommended as the drug is known to pass into breast milk. It may affect a nursing baby, causing drowsiness and irritability. The medication may also reduce milk production.

Interactions with other drugs

Some drugs interact with hydroxyzine and cause complications.

Monoamine oxidase inhibitors (MAOIs)

Taking MAOIs together with hydroxyzine may increase your risk of serious adverse effects, such as breathing problems or low blood pressure.

Medications that affect the heart rhythm (QT interval)

These include:

  • Antiarrhythmics

  • Antidepressants

  • Certain antibiotics

  • Methadone


Taking hydroxyzine with phenytoin can reduce its effectiveness.

CNS depressants

Hydroxyzine can cause CNS depression, which refers to the body’s nervous system slowing down. Taking other CNS depressant drugs with hydroxyzine may increase your risk of serious adverse reactions, including trouble breathing.

CNS depressants include:

  • Opioids (like oxycodone/OxyContin)

  • Certain sleep medications (like zolpidem/Ambien)

  • Benzodiazepines (like alprazolam/Xanax)

Medications that are metabolized by CYP2D6

These include fluoxetine (Prozac) and codeine. Your body uses CYP2D6 to break some medications down, but hydroxyzine can stop CYP2D6 from working. This may cause levels of CYP2D6-metabolized medications to increase in your body, raising your risk of side effects.

Blood pressure medications

This interaction can cause drowsiness and reduced alertness.

Examples of blood pressure medications include:

  • Angiotensin-converting enzyme (ACE) inhibitors

  • Angiotensin receptor blockers (ARBs)

  • Beta-blockers

  • Calcium channel blockers

  • Diuretics (water pills)

Allergy information

This medication is not recommended if you are allergic to hydroxyzine or other antihistamines, like cetirizine.

Though uncommon, hydroxyzine can cause allergic reactions with symptoms such as:

  • Hives

  • Swelling of the face, tongue, lips, and throat

  • Difficulty breathing

An allergic reaction to hydroxyzine may also cause severe skin reactions, like reddening of the skin, blistering, peeling, or rashes that form white or yellow pustules.

Seek emergency medical help if you develop any of these symptoms.

Tips and advice for taking hydroxyzine

Here are some tips to consider when taking hydroxyzine:

  • The main side effect of hydroxyzine is drowsiness. Avoid driving or operating machinery until you know how this medication affects you.

  • Do not take additional medications when taking hydroxyzine without your doctor’s guidance.

  • Hydroxyzine is typically only prescribed as a short-term medication. Tell your doctor if your symptoms do not improve, as another medication or dosage may be more helpful.

  • If you are taking hydroxyzine on a scheduled basis, try setting a calendar or phone reminder to avoid missing a dose. Tell your friends or family members to remind you to take your medication.

  • Keep this medicine out of a child’s reach and away from direct sunlight.

  • Do not freeze the liquid solution.

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Here at HealthMatch, we’ve done our best to ensure that the information provided in this article is helpful, up to date, and, most importantly, accurate.

However, we can’t replace the one-to-one advice of a qualified medical practitioner or outline all of the possible risks associated with this particular drug and your circumstances.

It is therefore important for you to note that the information contained in this article does not constitute professional medical or healthcare advice, diagnosis or recommendation of treatment and is not intended to, nor should be used to, replace professional medical advice. This article may not always be up to date and is not exhaustive of all of the risks and considerations relevant to this particular drug. In no circumstances should this article be relied upon without independent consideration and confirmation by a qualified medical practitioner.

Your doctor will be able to explain all possible uses, dosages, precautions, interactions with other drugs, and other potential adverse effects, and you should always talk to them about any kind of medication you are taking, thinking about taking or wanting to stop taking.

Curious about clinical trials?

Access the latest treatments and medications. unavailable elsewhere - entirely free of charge. We make it easy to take part.