What is the recommended dose of hydroxyzine (antihistamine) pamoate for itching?

Hydroxyzine Pamoate Dosing for Pruritus

For the management of pruritus due to allergic conditions such as chronic urticaria, the recommended dose of hydroxyzine pamoate is 25 mg three times daily or four times daily for adults. 1

Dosing Guidelines

• For adults with pruritus:

  • Standard dose: 25 mg three to four times daily 1
  • For nighttime pruritus: 25-50 mg at bedtime (beneficial for sleep due to sedative properties) 2
  • Maximum daily dose: 100 mg in divided doses 1

• For children with pruritus:

  • 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
  • Pediatric dosing of 0.7 mg/kg three times daily has shown effective pruritus relief with minimal sedation 3

Considerations for Special Populations

• Renal impairment: The dose of hydroxyzine should be halved in patients with moderate renal impairment 2
• Hepatic impairment: Hydroxyzine should be avoided in severe liver disease due to its sedating effects 2
• Pregnancy: Hydroxyzine is specifically contraindicated during early pregnancy according to UK manufacturer's guidelines 2

Clinical Efficacy

• Hydroxyzine has demonstrated effectiveness in treating pruritus through:
  • Direct H1-receptor antagonism 4
  • Inhibition of antigen-induced histamine release in vivo 4
  • Significant suppression of pruritus for up to 24 hours after a single dose, with peak effect between 2-12 hours 3

Timing Considerations

• Evening dosing of hydroxyzine (50 mg at bedtime) can help mitigate daytime sedation while maintaining antihistamine effects the following day 5
• First-generation antihistamines like hydroxyzine are particularly useful for nighttime pruritus due to their sedative properties 2
• Non-sedating second-generation antihistamines (like loratadine 10 mg daily) are preferred for daytime use 2

Common Side Effects and Precautions

• Sedation and somnolence are the most common side effects 6
• Other potential side effects include dry mouth and irritability 5
• Avoid concurrent use with drugs that have potential arrhythmic properties (including tricyclic antidepressants) 2

Treatment Algorithm for Pruritus

1. For mild or localized pruritus:

   • Begin with topical treatments (menthol, corticosteroids) 2
   • Add hydroxyzine 25 mg at bedtime if nighttime symptoms are problematic 2

2. For moderate pruritus:

   • Hydroxyzine 25 mg three to four times daily 1
   • Consider non-sedating antihistamine during day with hydroxyzine at night 2

3. For severe or widespread pruritus:

   • Hydroxyzine 25-50 mg three to four times daily 1
   • Consider combination therapy with H2 antihistamines for enhanced effect 7
   • For refractory cases, consider adding GABA agonists (pregabalin/gabapentin) 2

Hydroxyzine has been shown to be as effective as newer antihistamines for pruritus but with more sedation, making it particularly valuable for nighttime dosing when sleep disturbance from itching is problematic 6.