Hydroxyzine HCl is a prescription antihistamine used to treat anxiety, itching from allergic reactions, and as a sedative before or after surgery. Unlike newer antihistamines you can buy over the counter, hydroxyzine crosses into the brain, which is why it works for both allergic symptoms and anxiety. It comes in tablets, capsules, and liquid form.
How Hydroxyzine HCl Works
Hydroxyzine blocks histamine receptors throughout the body. Histamine is the chemical your immune system releases during allergic reactions, causing itching, hives, and swelling. By blocking histamine from reaching its receptors, hydroxyzine calms those reactions down.
What sets hydroxyzine apart from antihistamines like cetirizine or loratadine is that it also affects the central nervous system. It produces a calming, sedative effect that makes it useful for anxiety, though this same property is also responsible for the drowsiness most people experience. Its anti-anxiety effect is considered modest and comes largely from this general sedation rather than targeting specific anxiety pathways the way some other medications do.
Anxiety and Tension
Hydroxyzine HCl is FDA-approved for short-term relief of anxiety and tension. It’s not a long-term anxiety medication like SSRIs, but it can take the edge off acute episodes or serve as a bridge while other treatments take effect. Some prescribers favor it because, unlike benzodiazepines, hydroxyzine carries virtually no risk of dependence or withdrawal.
For adults, the typical dose for anxiety ranges from 50 to 100 mg taken up to four times daily. Children over six usually receive 50 to 100 mg per day split into smaller doses, while children under six are typically limited to 50 mg per day in divided doses. Your prescriber will usually start at the lower end to see how you respond, since sedation can be significant.
Itching and Allergic Skin Conditions
Hydroxyzine HCl is effective for itching caused by allergic reactions, including chronic hives (urticaria), eczema flares, contact dermatitis, and other histamine-driven skin conditions. It works well for nighttime itching in particular, since the sedation it causes can help you sleep through symptoms that might otherwise keep you awake.
For daytime itch management, newer non-drowsy antihistamines have largely taken over. Cleveland Clinic dermatologists note that second-generation antihistamines are equally effective for conditions like chronic hives without the sedation and anticholinergic side effects. Still, hydroxyzine remains a useful option when itching is severe or when non-drowsy antihistamines alone aren’t enough.
Sedation Before and After Surgery
Hospitals and surgical centers use hydroxyzine as a pre-procedure sedative to reduce anxiety and help patients relax before general anesthesia. It can also ease the transition after anesthesia wears off. For adults in this setting, doses range from 50 to 100 mg. Children receive a weight-based dose of about 0.6 mg per kilogram of body weight.
Common Side Effects
Drowsiness is by far the most common side effect, and for many people it’s pronounced enough to interfere with driving or concentration. This is also why hydroxyzine is sometimes prescribed specifically at bedtime for people who have trouble sleeping alongside their anxiety or itching.
Other frequent side effects include dry mouth, dizziness, blurred vision, constipation, and headache. These are tied to the drug’s anticholinergic properties, meaning it blocks a neurotransmitter called acetylcholine in addition to histamine. Most of these effects lessen after a few days as your body adjusts, but dry mouth tends to persist for as long as you take the medication.
Heart Rhythm Risk
Hydroxyzine carries a small but real risk of affecting heart rhythm by prolonging something called the QT interval, which can lead to a dangerous irregular heartbeat. This risk is highest in people who already have heart disease, a family history of sudden cardiac death, low potassium or magnesium levels, a slow heart rate, or who take other medications that affect heart rhythm. Current guidelines cap the maximum daily dose at 100 mg for adults specifically to reduce this risk.
Risks for Older Adults
The American Geriatrics Society lists hydroxyzine on its Beers Criteria, a widely used list of medications that are potentially inappropriate for adults over 65. The recommendation is to avoid it in this age group, with a “strong” rating. Older adults clear the drug more slowly, and its anticholinergic effects can cause confusion, increase fall risk, and contribute to delirium. Cumulative exposure to anticholinergic drugs like hydroxyzine is also associated with a higher risk of developing dementia over time. If hydroxyzine use in an older adult can’t be avoided, guidelines suggest keeping the daily dose at or below 50 mg and using it for as short a period as possible.
HCl vs. Pamoate: What’s the Difference
Hydroxyzine comes in two salt forms: HCl (sold under the brand name Atarax) and pamoate (sold as Vistaril). Your body converts both into the same active compound, and research shows no meaningful difference in effectiveness between them. The choice usually comes down to what’s available at your pharmacy and which formulation fits your dosing needs. Hydroxyzine HCl is often preferred when precise dose adjustments are needed, such as for children or older adults, because it comes in a wider range of tablet strengths and a liquid form that’s easy to measure.
In clinical practice, prescribers treat the two as interchangeable. If your pharmacy switches you from one to the other at an equivalent dose, you can expect the same effects.