Hydroxyzine: Usage, Side Effects, and Precautions

Hydroxyzine is an antihistamine. While antihistamines most commonly treat allergies, hydroxyzine is also prescribed for the treatment of anxiety.

However, hydroxyzine has some anticholinergic properties, meaning it blocks the action of acetylcholine. This brain chemical (or neurotransmitter) plays a role in many bodily functions, including muscle contraction and digestion.

So taking anything with anticholinergic properties increases the risk of side effects.

To help you understand more about hydroxyzine, in this article, I’ll explain what it’s used for, its possible side effects, drug interactions, and potential alternatives.

I’ll also discuss when to see a healthcare provider about hydroxyzine.

Hydroxyzine Usage

Hydroxyzine is a first-generation H-1 receptor antihistamine in the same class of medications as diphenhydramine (Benadryl).

H-1 antihistamines work on histamine 1 receptors, which are found throughout the body in:

• Cardiac tissue
• The gastrointestinal tract
• Cells lining blood vessels
• Respiratory smooth muscle
• Immune cells
• The uterus
• The central nervous system

When the H-1 receptor at any of these locations is stimulated, it results in common symptoms associated with allergies such as:

• Fluid moving between blood vessels
• Flushing from the dilation of veins
• Stimulation of airways leading to coughing
• Smooth muscle contraction in the lungs and gastrointestinal tract
• Hives, rashes, and anaphylaxis in extreme reactions

Hydroxyzine can minimize the effects of histamine and may be prescribed for:

• Itching from skin reactions such as hives or contact dermatitis
• Symptoms of anxiety, including generalized anxiety disorder (GAD)
• Tension
• Sedation before general anesthesia
• Allergic reactions

Common dosage

Hydroxyzine is available as a generic drug and under the brand names Atarax and Vistaril.

The common dosage for hydroxyzine depends on the reason it is prescribed:

• Anxiety: 50-100 mg, four times per day
• Skin reactions: 25 mg, 3-4 times per day
• Allergies: 25 mg, 3-4 times per day

For any diagnosis, healthcare providers prescribe the lowest effective dose of hydroxyzine to minimize the risk of side effects. 

Is hydroxyzine habit forming?

Unlike other anti-anxiety medications, the use of hydroxyzine is not habit-forming.

How quickly does hydroxyzine work?

Hydroxyzine easily crosses the blood-brain barrier and produces an effect quickly, usually in 15-30 minutes. 

The half-life of hydroxyzine is three hours, meaning it begins to wear off by then.

Most of its effects will stop within 4-6 hours.

Hydroxyzine Side Effects

Hydroxyzine causes some common side effects related to it being an antihistamine and also due to its anticholinergic effects.

In rare cases, these effects may be more serious. 

Common side effects

Common side effects of hydroxyzine may include:

• Drowsiness, sleepiness, and fatigue
• Dry mouth
• Constipation
• Dizziness
• Confusion
• Headache

These side effects may be more noticeable with higher dosages or when suddenly changing dosages.

More serious side effects

Less commonly, hydroxyzine can cause serious side effects.

If you experience severe reactions such as those below, discontinue hydroxyzine and talk to your healthcare provider immediately:

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

Hydroxyzine Drug Interactions

Hydroxyzine may interact with other medications.

To avoid complications, always tell your healthcare provider everything that you take, including prescription drugs, over-the-counter (OTC) medicines, vitamins, supplements, and herbs.

Do not take the following medications if you take hydroxyzine:

• Other sleeping pills, sedatives, or tranquilizers
• Other antihistamines
• Narcotics
• Muscle relaxers
• Certain antidepressants such as citalopram (Celexa) or fluoxetine (Prozac)
• Antipsychotics
• Anti-anxiety medication
• Anticonvulsants
• Certain antibiotics such as azithromycin (Zithromax), clarithromycin (Biaxin), erythromycin (Eryc), and others
• Certain heart rhythm medications such as amiodarone (Cordarone, Nexterone, others), quinidine (Nuedexta), sotalol (Sorine, Sotylize), and others
• Certain cancer treatments
• Malaria medication
• Medication for HIV/AIDS
• Anti-nausea medications such as ondansetron (Zofran)

What to avoid

Certain medical conditions make hydroxyzine unsafe.

Do not take hydroxyzine if you have:

• Allergies to any ingredients in hydroxyzine
• Allergies to cetirizine (Zyrtec) or levocetirizine (Xyzal)
• Prolonged QT interval on an EKG
• A history of heart attack, heart failure, or heart disease
• A history of low blood levels of potassium or magnesium

Additionally, older adults (over age 65) should not take hydroxyzine. Other medications are safer and effective for this age group.

Due to an increased risk of birth defects, do not take hydroxyzine if you are pregnant, plan to become pregnant, or are breastfeeding.

Hydroxyzine can make you very sleepy. Do not take hydroxyzine if you have to operate a vehicle or machinery until you know how the medication affects you. 

Because it’s a depressant, alcohol can increase the effects of hydroxyzine. Do not consume alcohol while you are taking hydroxyzine.

Hydroxyzine Alternatives

Alternatives to hydroxyzine depend on the reason the medication was prescribed and may include:

• For anxiety: alprazolam (Xanax)
• For skin or allergic reactions: diphenhydramine (Benadryl)

However, alprazolam is a controlled substance that can be habit-forming and comes with a risk of addiction, so hydroxyzine is often a preferred anxiety treatment.

And diphenhydramine is typically only used for short-term allergies or reactions.

When to See a Doctor

If you have questions about the use of hydroxyzine for allergies or anxiety, a healthcare provider can identify whether it is appropriate for you.

If you have anxiety that impacts your quality of life, talk to a healthcare provider. They can recommend treatment, which may include medication, therapy, lifestyle changes, or a combination of treatment options.

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.