What is the recommended dosing for hydroxyzine (antihistamine) to relieve pruritus (itch)?

Hydroxyzine Dosing for Pruritus

The recommended dosing of hydroxyzine for pruritus in adults is 25 mg three to four times daily (10-25 mg QID), with potential for adjustment based on symptom severity and sedation effects. 1, 2

Adult Dosing Guidelines

Initial Dosing

• Start with hydroxyzine 25 mg three to four times daily for most adults 1, 2
• For nighttime pruritus: Consider higher evening dose (25-50 mg) to leverage sedative effects 2
• Maximum daily dose: 100 mg in divided doses 1

Dosing Adjustments

• Increase or decrease dose based on:
  • Pruritus severity
  • Sedation tolerance
  • Time of day (higher doses at night if sleep disruption is an issue)

Pediatric Dosing

• Children under 6 years: 50 mg total daily dose divided into multiple administrations 1
• Children over 6 years: 50-100 mg total daily dose divided into multiple administrations 1
• Research supports 0.7 mg/kg three times daily as effective with less sedation than higher doses 3

Clinical Application by Pruritus Severity

Mild Pruritus (Grade 1)

• Hydroxyzine 10-25 mg QID or at bedtime 2
• Can be used alongside topical treatments like emollients and class-appropriate topical corticosteroids 2

Moderate Pruritus (Grade 2)

• Hydroxyzine 25 mg QID 2
• Consider combination with non-sedating antihistamines during daytime (cetirizine/loratadine 10 mg daily) 2

Severe Pruritus (Grade 3)

• Hydroxyzine 25-50 mg QID 2
• May need to combine with other agents like GABA agonists (pregabalin, gabapentin) if inadequate response 2

Efficacy Considerations

• Hydroxyzine has demonstrated significant improvement in pruritus scores and quality of life in real-world settings 4
• In comparative studies, hydroxyzine 25 mg/day showed similar efficacy to doxepin and superior results to cetirizine in controlling chronic pruritus 5
• Onset of action typically occurs within 1-2 hours, with peak effect at 2-4 hours 3
• Duration of antipruritic effect can last up to 24 hours, with greatest suppression (>85%) from 2-12 hours after administration 3

Important Considerations and Cautions

• Sedation is the most common side effect; adjust timing of doses accordingly 4, 5
• Other potential side effects include dizziness, dry mouth, constipation 4
• Hydroxyzine should be considered primarily for nighttime use due to its sedative properties 2
• For daytime pruritus, consider non-sedating second-generation antihistamines as first-line 2
• Avoid prolonged use in elderly patients due to anticholinergic effects 6

Treatment Algorithm

1. Start with hydroxyzine 25 mg three to four times daily
2. Assess response after 2 weeks
3. If inadequate response but tolerable side effects, increase frequency or dose
4. If excessive sedation, reduce dose or switch to non-sedating antihistamine for daytime use
5. For persistent symptoms despite optimized hydroxyzine dosing, consider adding:
   • GABA agonists (pregabalin/gabapentin)
   • Topical treatments
   • Short-course systemic corticosteroids for severe flares

By following this structured approach to hydroxyzine dosing, clinicians can effectively manage pruritus while minimizing adverse effects.