Hydroxyzine

Hydroxyzine is a first-generation antihistamine that crosses the blood-brain barrier and produces anxiolytic, sedative, and antipruritic effects through multiple receptor interactions ^{[1, 3]}:

1. Histamine H1 receptor antagonism (primary): Central H1 blockade produces sedation and anxiolysis. Peripheral H1 blockade reduces itching and allergic symptoms ^{[1, 3]}.

2. Serotonin 5-HT2A receptor antagonism: This contributes to anxiolytic effects beyond simple sedation and is the same mechanism exploited by some atypical antipsychotics ^{[1, 3]}.

3. Muscarinic receptor antagonism: Produces anticholinergic effects (dry mouth, blurred vision, constipation, urinary retention) ^{[1, 3]}.

Hydroxyzine occupies a unique niche in anxiety treatment as a non-addictive, non-controlled medication that provides rapid anxiolysis (30-60 minutes) without the dependence risk of benzodiazepines. It is particularly useful in ^{[1, 3, 4]}: - Patients with substance use disorders - Elderly patients (though anticholinergic effects are a concern) - Patients who need PRN (as-needed) anxiety relief without benzodiazepine risks - Perioperative sedation and anxiety - Allergic conditions with comorbid anxiety

In a landmark study, Lader and Scotto showed hydroxyzine was comparable to buspirone and superior to placebo for generalized anxiety disorder, with the advantage of faster onset ^[4].

First dose: Onset within 15-30 minutes. Sedation is the most noticeable effect. Anxiolysis occurs simultaneously. Dry mouth and drowsiness are common ^[1].

Regular dosing (days 1-7): Sedation may be most pronounced in the first few days. Some tolerance to sedation develops, but anxiolytic and antipruritic effects persist. Anticholinergic effects (dry mouth, constipation) may be bothersome ^[1].

Weeks 2-4: If used regularly for anxiety, effects are maintained without dose escalation. No tolerance to the anxiolytic effect develops. No physical dependence forms ^{[1, 4]}.

Long-term: Hydroxyzine is safe for long-term use without addiction risk. However, anticholinergic burden should be considered, especially in elderly patients. The main long-term concern is the QTc prolongation risk at higher doses ^{[1, 5]}.

Food: Hydroxyzine can be taken with or without food ^[1].

Alcohol: Alcohol should be avoided with hydroxyzine. Both are CNS depressants, and the combination significantly increases sedation, impairs motor function, and increases fall risk. Unlike the potentially fatal benzodiazepine-alcohol interaction, the hydroxyzine-alcohol combination is not typically life-threatening but can cause excessive sedation ^[1].

Grapefruit: May modestly increase hydroxyzine levels via CYP3A4 inhibition. Not typically clinically significant ^[1].

Caffeine: Caffeine may partially offset sedation. No dangerous interaction ^[1].

Anxiety (adults): 25-100 mg 3-4 times daily. Start at 25 mg. Most patients respond to 75-200 mg/day in divided doses ^[1].

Pruritus (adults): 25 mg 3-4 times daily ^[1].

Sedation/preoperative: 50-100 mg as a single dose ^[1].

Pediatric (>6 years): 50-100 mg/day in divided doses. Under 6: 50 mg/day in divided doses ^[1].

Elderly: Start at 10-25 mg 1-2 times daily. Increase slowly. More sensitive to anticholinergic and sedative effects. Lower doses are usually effective ^[1].

PRN (as-needed) use: 25-50 mg for acute anxiety episodes. Can be repeated every 4-6 hours. This is a common and effective use pattern ^[1].

QTc considerations: Avoid doses above 100 mg/day in patients with QTc prolongation risk factors. Obtain baseline ECG in patients with cardiac history ^{[1, 5]}.

Renal impairment: Reduce daily dose by 50% in moderate-severe impairment ^[1]. Hepatic impairment: Reduce daily dose by 50% ^[1].

Generic hydroxyzine is very affordable, costing approximately $4-10/month ^[1].

Pharmacy discount programs: Available on virtually all $4 generic lists. GoodRx prices are typically $3-8/month ^[1].

Brand names: Both Vistaril and Atarax are no longer manufactured as brand-name products. Only generic is available ^[1].

Not a controlled substance: No quantity limits, no prescribing restrictions. Can be called in to the pharmacy (no paper prescription required in most states) ^[1].

Insurance: Tier 1 on all formularies. No prior authorization ever required ^[1].

Pregnancy: Hydroxyzine is classified as FDA Pregnancy Category C. Animal studies have shown some evidence of fetal abnormalities at high doses. There are no adequate human studies. Hydroxyzine should be avoided in early pregnancy when possible. However, it has been used for nausea and anxiety in pregnancy by some providers when benefits outweigh risks ^[1].

Breastfeeding: Hydroxyzine's active metabolite cetirizine is found in breast milk. First-generation antihistamines may reduce milk production and cause infant sedation. Cetirizine (the metabolite) is generally considered safer during breastfeeding as a standalone drug. If an antihistamine is needed during breastfeeding, second-generation agents (cetirizine, loratadine) are generally preferred ^[1].

Generic only: Both brand-name Vistaril and Atarax have been discontinued. All prescriptions are filled with generic hydroxyzine (hydrochloride or pamoate salts) ^[1].

Both salts are equivalent: Hydroxyzine HCl and hydroxyzine pamoate contain the same active ingredient. Pamoate is often associated with the name Vistaril, HCl with Atarax, but they are clinically interchangeable ^[1].

Cost: $4-10/month generic. One of the most affordable anxiety and antihistamine medications ^[1].