What is the recommended dosage of Hydroxyzine (hydroxyzine) for an adult patient with no known medical history or allergies, presenting with symptoms of anxiety or itching?

Hydroxyzine Dosing for Anxiety and Pruritus in Adults

For anxiety, start hydroxyzine 50-100 mg four times daily; for pruritus, use 25 mg three to four times daily, or alternatively 25-50 mg at bedtime to leverage sedative properties while minimizing daytime impairment. 1

Anxiety Management

Standard Dosing

• The FDA-approved dose for anxiety and tension associated with psychoneurosis is 50-100 mg four times daily in adults 1
• Clinical trials demonstrate hydroxyzine 50 mg/day produces statistically significant anxiolytic effects beginning in the first week of treatment, with superiority over placebo maintained throughout 4 weeks 2
• Hydroxyzine shows particular efficacy for the cognitive component of anxiety and demonstrates no rebound anxiety or withdrawal symptoms upon abrupt discontinuation 2, 3

Clinical Considerations for Anxiety

• While hydroxyzine is effective for generalized anxiety disorder, the evidence base is limited by small sample sizes and high risk of bias in available studies 4
• Hydroxyzine demonstrates equivalent efficacy to benzodiazepines and buspirone but with a more favorable dependency profile 4, 3
• The most common side effect is transient sleepiness (28% vs 14% placebo), which typically appears during the first week and progressively diminishes with continued treatment 2

Pruritus Management

Dosing Strategy

• For daytime pruritus: 25 mg three to four times daily 1
• For nighttime-predominant itching: 25-50 mg at bedtime is the preferred approach, capitalizing on sedative properties to improve sleep while avoiding daytime performance impairment 5, 6
• The American Academy of Dermatology recommends hydroxyzine specifically for nighttime use in pruritus patients, while non-sedating second-generation antihistamines are preferred for daytime 5

Treatment Algorithm for Pruritus

• Mild/localized pruritus: Begin with topical treatments; add hydroxyzine 25 mg at bedtime if nighttime symptoms are problematic 6
• Moderate pruritus: Use a non-sedating antihistamine during the day with hydroxyzine at night 6
• Severe/widespread pruritus: Consider combination therapy with H2 antihistamines (such as cimetidine) for better control 7, 6

Critical Dosing Adjustments

Renal Impairment

• Moderate renal impairment: Halve the dose 7, 5
• Severe renal impairment (CrCl <10 mL/min): Avoid hydroxyzine entirely 7

Hepatic Impairment

• Avoid hydroxyzine in severe liver disease due to inappropriate sedating effects 7, 5

Special Populations

• Pregnancy: Hydroxyzine is specifically contraindicated in early pregnancy; if antihistamine therapy is necessary, chlorphenamine is preferred due to its long safety record 7, 5
• Elderly patients: Avoid in those with cognitive impairment due to anticholinergic effects 5

Timing Strategy to Minimize Side Effects

Evening dosing of hydroxyzine (50 mg at bedtime) eliminates the psychomotor performance degradation seen with divided doses while maintaining full H1-receptor antagonism the following morning. 8

• Hydroxyzine 25 mg twice daily significantly prolongs both simple and choice reaction times without development of tolerance over 5 days 9
• Bedtime dosing maintains skin H1-receptor antagonism while alleviating reaction time prolongations seen with divided doses 8
• Subjective symptoms (drowsiness, dry mouth, irritability) remain present but are less problematic than with divided dosing 8

Common Pitfalls

• Performance impairment is not predicted by subjective symptoms: Patients may have prolonged reaction times without feeling drowsy, making hydroxyzine inappropriate for those performing critical tasks during daytime hours 9
• Avoid concomitant CNS depressants: Combining with other sedating medications enhances performance impairment 5
• Do not assume tolerance develops: Neither objective performance measures nor subjective symptoms show tolerance development during 5 days of administration 9