What is the typical dosing of hydroxyzine (antihistamine) for itching?

Hydroxyzine Dosing for Pruritus

For the management of pruritus due to allergic conditions, hydroxyzine should be dosed at 25 mg three to four times daily for adults. 1

Standard Dosing Regimen

Adults:

• Standard dose: 25 mg three to four times daily 1
• Maximum daily dose: 100 mg in divided doses 1

Children:

• Under 6 years: 50 mg total daily dose, divided throughout the day 1
• Over 6 years: 50-100 mg total daily dose, divided throughout the day 1

Special Considerations

Timing of Administration

• Consider evening/bedtime dosing to minimize daytime sedation
• Evening dosing of hydroxyzine (50 mg at bedtime) has been shown to maintain antihistamine effects while reducing daytime drowsiness and psychomotor impairment 2

Renal Impairment

• In moderate renal impairment, the dose should be halved 3
• Avoid in severe renal impairment (creatinine clearance <10 mL/min) 3

Hepatic Impairment

• Avoid in severe liver disease due to inappropriate sedating effects 3

Pregnancy

• Hydroxyzine is specifically contraindicated during early pregnancy 3
• Consider alternative antihistamines if treatment is necessary during pregnancy

Therapeutic Strategy for Difficult Cases

For patients with inadequate response to standard hydroxyzine dosing:

1. Consider adding a non-sedating antihistamine during the day:

   • This allows for 24-hour coverage while minimizing daytime sedation
   • Examples: fexofenadine 180 mg, loratadine 10 mg, or cetirizine 10 mg daily 3

2. Consider adding an H2 antagonist:

   • The addition of an H2 antihistamine (such as cimetidine 200 mg four times daily) may provide better control of urticaria than H1 antihistamines alone 4
   • This combination has shown moderate to good improvement in approximately 85% of patients not responding to H1 antagonists alone 4

3. For nighttime pruritus:

   • Hydroxyzine 10-50 mg at bedtime can be added to a non-sedating antihistamine taken during the day 3
   • This approach may help patients sleep better while minimizing daytime sedation 3

Cautions and Monitoring

• Monitor for excessive sedation, especially in elderly patients
• Be aware of potential anticholinergic side effects (dry mouth, urinary retention, constipation)
• Avoid concomitant use with drugs that prolong QT interval
• Avoid alcohol and other CNS depressants while taking hydroxyzine

Alternative Options for Pruritus Management

If hydroxyzine is ineffective or contraindicated, consider:

• Topical treatments: menthol, clobetasone butyrate 3
• Other systemic options: gabapentin, pregabalin, paroxetine, mirtazapine, or naltrexone 3
• Avoid crotamiton cream, topical capsaicin, and calamine lotion as they have not shown efficacy for generalized pruritus 3

Remember that hydroxyzine's sedating properties can be beneficial for nighttime dosing but may limit daytime use in patients who need to remain alert for work or driving.