What is the appropriate use and dosage of Hydroxyzine for adults with anxiety or itching?

Hydroxyzine: Clinical Use and Dosing for Anxiety and Pruritus in Adults

Hydroxyzine is effective for managing both anxiety and pruritus in adults, with FDA-approved dosing of 50-100 mg four times daily for anxiety and 25 mg three to four times daily for pruritus, though it should be reserved primarily for nighttime use due to significant sedative effects that impair driving and cognitive function. 1

Primary Indications and Dosing

For Anxiety Management

• Standard dosing: 50-100 mg four times daily for symptomatic relief of anxiety and tension associated with psychoneurosis 1
• Hydroxyzine demonstrates superiority over placebo on all anxiety measures starting from the first week of treatment, with efficacy maintained throughout 4 weeks without rebound anxiety or withdrawal symptoms upon abrupt discontinuation 2, 3
• The British Journal of Dermatology recommends 10-50 mg per dose, though this is not considered first-line treatment due to limited high-quality evidence 2

Important caveat: While older studies from the 1990s showed efficacy, a 2010 Cochrane review concluded that due to high risk of bias in available studies, hydroxyzine cannot be recommended as a reliable first-line treatment for generalized anxiety disorder 4

For Pruritus (Itching)

• Standard dosing: 25 mg three to four times daily for pruritus due to allergic conditions such as chronic urticaria, atopic dermatitis, and contact dermatoses 1
• Preferred approach: 10-50 mg at bedtime combined with a non-sedating second-generation antihistamine during the day for patients with urticaria who have sleep disturbances 2, 5
• The American Academy of Dermatology recommends hydroxyzine specifically for nighttime use due to its sedative properties, while non-sedating antihistamines are preferred for daytime 5

Critical Safety Considerations

Sedation and Performance Impairment

• Drivers in fatal accidents are 1.5 times more likely to be taking first-generation antihistamines like hydroxyzine 2
• Performance impairment occurs without subjective awareness of drowsiness, and impaired driving worsens with concurrent activities like cell phone use 2
• Hydroxyzine significantly prolongs both simple and choice reaction times without development of tolerance over 5 days of administration 6
• No correlation exists between subjective drowsiness symptoms and objective performance impairment, meaning patients cannot reliably assess their own impairment 6

Contraindications and Precautions

• Contraindicated in early pregnancy 2, 5
• Avoid in severe liver disease due to inappropriate sedating effects 2, 5
• Avoid in elderly patients with cognitive impairment due to anticholinergic effects and increased risk of falls and fractures 2, 5

Dose Adjustments for Special Populations

Renal Impairment

• Moderate renal impairment (eGFR 30-60 mL/min): Reduce dose by 50% 2, 5
• Severe renal impairment (eGFR <30 mL/min): Avoid hydroxyzine 2

Elderly Patients

• Start with lower doses and monitor closely for psychomotor impairment, falls, and anticholinergic effects 2
• The American Geriatrics Society recommends avoiding hydroxyzine in elderly patients with cognitive impairment 5

Practical Treatment Algorithm

For Pruritus Management

1. First-line: Non-sedating second-generation antihistamine (cetirizine 10 mg, loratadine 10 mg, or fexofenadine) during daytime 7, 5
2. If sleep disturbance present: Add hydroxyzine 10-50 mg at bedtime to the daytime non-sedating antihistamine 2, 5
3. If inadequate response: Consider increasing the daytime antihistamine dose up to 4-fold before adding or increasing hydroxyzine 7

For Anxiety Management

• Hydroxyzine 50-100 mg four times daily can be used, but benzodiazepines (lorazepam 0.5-1 mg four times daily) are more commonly recommended for acute anxiety in current guidelines 8, 1
• Consider hydroxyzine primarily when sedation is desired or in pediatric populations where it is recommended for chemical restraint 8, 2

Common Pitfalls to Avoid

• Do not assume patients can self-assess impairment: Objective performance deficits occur without subjective drowsiness 6
• Do not use AM/PM dosing expecting no daytime effects: Hydroxyzine's prolonged half-life may result in daytime drowsiness even with nighttime-only dosing 2
• Do not combine with other sedating medications without careful consideration of additive effects 8
• Do not use as monotherapy for chronic urticaria: Second-generation antihistamines should be the foundation, with hydroxyzine added only for nighttime symptoms 2, 7

Tolerability Profile

• Most common side effects: sleepiness (28% vs 14% placebo), dry mouth (14% vs 5%), weight gain (12% vs 10%), and loss of concentration (9% vs 8%) 3
• Sleepiness typically appears during the first week and may progressively diminish but does not fully resolve 3
• Hydroxyzine is associated with higher rates of drowsiness compared to benzodiazepines and buspirone 2