What is the recommended dose of hydroxyzine (an antihistamine) for insomnia?

Hydroxyzine for Insomnia: Dosage Recommendations

Hydroxyzine is not recommended for the treatment of insomnia based on current clinical practice guidelines, with a recommended dose of 25-50 mg at bedtime when used off-label for short-term sleep issues.

Guideline Recommendations for Insomnia Treatment

• The American Academy of Sleep Medicine explicitly does not recommend antihistamines like diphenhydramine for sleep onset and sleep maintenance insomnia in adults 1
• While hydroxyzine is not specifically mentioned in these guidelines, as a first-generation antihistamine it falls into the same category as diphenhydramine, which is explicitly not recommended 1
• The guidelines instead recommend FDA-approved medications such as:
  • Benzodiazepine receptor agonists (eszopiclone, zaleplon, zolpidem) 1
  • Orexin receptor antagonists (suvorexant) 1
  • Low-dose doxepin for sleep maintenance insomnia 1

Hydroxyzine Dosing When Used Off-Label

• According to the FDA label, hydroxyzine is approved for anxiety but not specifically for insomnia 2
• When used off-label for sedation, the FDA label indicates:
  • Adults: 50 to 100 mg as a sedative 2
  • Children: 0.6 mg/kg of body weight 2
• Recent systematic review evidence suggests doses of 25-50 mg at bedtime have been studied for insomnia, though with mixed efficacy 3

Safety Considerations

• Common side effects include:

  • Dry mouth (most common reported adverse effect) 3
  • Daytime drowsiness that may persist into the next day 4, 5
  • Potential for impaired reaction times and psychomotor performance 4

• Important safety concerns:

  • Hydroxyzine causes significant objective sedation and slower reaction times for at least four hours after administration 4
  • Patients may not be aware of their impairment, making this particularly dangerous 4
  • Evening dosing may mitigate some daytime impairment but does not eliminate subjective symptoms 5
  • Potential drug interactions exist, including a case report of priapism when combined with risperidone 6

Clinical Approach to Insomnia Treatment

• First-line pharmacologic options should include:

  • Zolpidem 10 mg for sleep onset and maintenance insomnia 1, 7
  • Eszopiclone 2-3 mg for sleep onset and maintenance insomnia 1
  • Zaleplon 10 mg for sleep onset insomnia 1
  • Ramelteon 8 mg for sleep onset insomnia 1
  • Low-dose doxepin (3-6 mg) for sleep maintenance insomnia 1

• If hydroxyzine is used despite these recommendations:

  • Start with 25 mg at bedtime 3
  • May increase to 50 mg if needed and tolerated 3
  • Use for shortest duration possible 3
  • Monitor for next-day impairment 4, 5

Important Caveats

• Hydroxyzine should be considered only when first-line agents have failed, are contraindicated, or not tolerated 3
• Patients should be warned about potential next-day impairment even if they don't subjectively feel impaired 4
• Evening dosing strategy (single bedtime dose rather than divided doses) may help reduce but not eliminate daytime impairment 5
• Long-term efficacy and safety data for hydroxyzine in insomnia are lacking 3