What is the recommended dosing for hydroxyzine (antihistamine)?

Hydroxyzine Dosing Recommendations

For adults, hydroxyzine should be dosed at 25 mg three to four times daily for allergic conditions and pruritus, or 50-100 mg four times daily for anxiety. 1

Adult Dosing by Indication

• Allergic conditions and pruritus:

  • 25 mg three to four times daily 2, 1
  • Can be used for dermatologic conditions with pruritus covering <10% BSA
  • Often combined with topical corticosteroids for enhanced effect

• Anxiety:

  • 50-100 mg four times daily 1
  • Demonstrated efficacy at 50 mg/day in generalized anxiety disorder 3, 4

• Pre-medication/sedation:

  • 50-100 mg as a single dose 1

Pediatric Dosing

• Children under 6 years:

  • 50 mg total daily dose, divided throughout the day 1

• Children over 6 years:

  • 50-100 mg total daily dose, divided throughout the day 1

Special Populations and Considerations

Liver Disease

• Reduce starting dose by 50% in patients with liver disease 5
• Monitor liver function tests before and during treatment
• Consider second-generation antihistamines as alternatives 5

Elderly Patients

• Start at lower doses (e.g., 10-25 mg) due to increased sensitivity
• Higher risk of anticholinergic effects and falls 5
• Monitor for cognitive impairment

Side Effect Profile

The most common side effects include:

• Drowsiness/sleepiness (28% vs 14% with placebo) 3, 6
• Dry mouth (14% vs 5% with placebo) 3
• Weight gain (12% vs 10% with placebo) 3
• Loss of concentration (9% vs 8% with placebo) 3

Important Cautions

1. Cognitive impairment: Hydroxyzine significantly prolongs both simple and choice reaction times compared to non-sedating antihistamines like terfenadine 6

2. Occupational hazards: Avoid activities requiring mental alertness until response to the medication is known

3. Tolerance: Unlike benzodiazepines, hydroxyzine does not appear to develop tolerance to its anxiolytic effects over time 3, 4

4. Withdrawal: No rebound anxiety or withdrawal symptoms have been reported after abrupt discontinuation 3

Clinical Pearls

• Sleepiness typically appears during the first week of treatment and progressively diminishes with continued use 3
• For pruritus management, combining hydroxyzine with topical corticosteroids often provides better relief than either agent alone 2
• When used for anxiety, the anxiolytic effect begins during the first week and is maintained throughout treatment 3, 4
• Despite subjective drowsiness, patients may not accurately perceive objective performance impairment, making caution with driving and operating machinery essential 6