Vistaril (Hydroxyzine) Dosage and Usage
Vistaril (hydroxyzine) is dosed at 25 mg three to four times daily for pruritus in adults, and 50-100 mg four times daily for anxiety, with pediatric dosing of 50 mg daily in divided doses for children under 6 years and 50-100 mg daily in divided doses for children over 6 years. 1
Indications and Dosing
For Pruritus (Itching)
- Adults: 25 mg three to four times daily 1
- Children under 6 years: 50 mg daily in divided doses 1
- Children over 6 years: 50-100 mg daily in divided doses 1
- Indicated for allergic conditions including chronic urticaria, atopic dermatitis, and contact dermatoses 1
For Anxiety and Tension
- Adults: 50-100 mg four times daily 1
- Children under 6 years: 50 mg daily in divided doses 1
- Children over 6 years: 50-100 mg daily in divided doses 1
- Used for symptomatic relief of anxiety associated with psychoneurosis and as adjunct in organic disease states 1
As Premedication/Sedation
- Adults: 50-100 mg 1
- Children: 0.6 mg/kg of body weight 1
- When initiated intramuscularly, subsequent doses may be given orally 1
Clinical Efficacy Evidence
Anxiety Treatment
- Onset of action: Hydroxyzine demonstrates superiority over placebo on all anxiety measures from the first week of treatment, with early improvement in cognitive components of anxiety 2, 3
- Sustained efficacy: Anxiolytic effect is maintained throughout 4 weeks of treatment and persists after abrupt discontinuation without rebound anxiety or withdrawal symptoms 3
- Long-term use: A 3-month double-blind study showed mean HAM-A score reduction of -12.16 with hydroxyzine versus -9.64 with placebo (p=0.019), with comparable efficacy to bromazepam 4
- Fixed dosing: 50 mg daily has been established as effective in generalized anxiety disorder 2, 3
Comparative Effectiveness
- Hydroxyzine demonstrates greater and more rapid cognitive improvement compared to lorazepam 2
- Equivalent efficacy to benzodiazepines (chlordiazepoxide) and buspirone in head-to-head trials 5
- However, a Cochrane review noted high risk of bias in included studies, limiting the strength of recommendation as first-line treatment 5
Important Clinical Considerations
Adverse Effects
- Most common: Sleepiness/drowsiness (28% vs 14% with placebo), which typically appears during the first week and progressively diminishes 3
- Other effects: Weight gain (12%), dry mouth (14%), loss of concentration (9%), insomnia (9%) 3
- Comparative tolerability: Higher rate of drowsiness compared to other anxiolytics, but generally well-tolerated 5, 4
- Safety profile: Lack of organ toxicity and absence of dependency with long-term use 2
Special Populations
- Renal impairment: Hydroxyzine dose should be halved in moderate renal impairment; avoid in severe renal impairment (creatinine clearance <10 mL/min) 6
- Hepatic impairment: Should be avoided in severe liver disease due to inappropriate sedating effects 6
- Pregnancy: Specifically contraindicated during early stages of pregnancy; best to avoid all antihistamines in first trimester 6
- Elderly patients: Use caution due to increased sensitivity to anticholinergic and sedating effects 6
Drug Interactions
- Contraindicated with: Mizolastine should not be taken with drugs inhibiting hepatic metabolism via cytochrome P450 (macrolide antibiotics, imidazole antifungals) or drugs with arrhythmic properties (tricyclic antidepressants) 6
- Caution with: Other sedating agents due to increased risk of respiratory depression 6