What is the recommended dosage and usage of Doxylamine for insomnia and allergies?

Doxylamine Dosage and Usage for Insomnia and Allergies

For insomnia, the recommended dosage of doxylamine is one tablet (25 mg) taken 30 minutes before bedtime in adults and children 12 years and older. 1

Doxylamine for Insomnia

Dosage and Administration

• Adults and children 12 years and older: Take one tablet (25 mg) 30 minutes before bedtime 1
• Children under 12 years: Not recommended 1
• Duration: Intended for short-term use only for occasional insomnia 2

Efficacy for Insomnia

• Doxylamine is not recommended by the American Academy of Sleep Medicine for treating either sleep onset or sleep maintenance insomnia 3
• When compared to other sleep medications:
  • Doxepin (3-6 mg) is recommended for sleep maintenance insomnia with clinically significant improvements in wake after sleep onset (WASO), total sleep time (TST), and sleep efficiency (SE) 3, 4
  • Other recommended medications include eszopiclone, temazepam, suvorexant, and zolpidem, which show better efficacy profiles 4

Cautions and Side Effects

• First-generation antihistamines like doxylamine can cause:
  • Daytime sedation and impairment
  • Anticholinergic side effects
  • Potential cognitive impairment, especially concerning in older adults 4
• Potential for abuse and addiction has been reported 5
  • A case report documented a patient who started at 25 mg/day and escalated to 125 mg/day over 3 years 5

Pharmacokinetic Considerations

Food Effects

• High-fat, high-calorie food intake does not significantly affect the pharmacokinetics of doxylamine 6
• Similar bioavailability is observed in both fed and fasting states:
  • Fasting state: Mean Cmax 118.21 ng/mL; Mean AUCt 1746.97 ng·h/mL
  • Fed state: Mean Cmax 120.99 ng/mL; Mean AUCt 1712.20 ng·h/mL 6

Dose Proportionality

• Doxylamine exhibits linear and dose-dependent pharmacokinetics between 12.5 mg and 25 mg doses 7
• Exposure increases proportionally with dose:
  • 12.5 mg: Mean Cmax 61.94 ng/mL; Mean AUCt 817.33 ng·h/mL
  • 25 mg: Mean Cmax 124.91 ng/mL; Mean AUCt 1630.85 ng·h/mL 7

Clinical Considerations and Alternatives

Important Caveats

• Despite being commonly available over-the-counter, doxylamine is not recommended by clinical guidelines for insomnia treatment 3, 4
• Better alternatives exist for both sleep onset and maintenance insomnia:
  • For sleep onset: Zolpidem (10 mg for adults, 5 mg for elderly), zaleplon (10 mg), or ramelteon (8 mg) 4
  • For sleep maintenance: Doxepin (3-6 mg), eszopiclone (2-3 mg), temazepam (15 mg), or suvorexant (10-20 mg) 4

Efficacy in Clinical Studies

• A Russian study found that doxylamine was effective for short-term insomnia with significant improvements in insomnia severity, sleep quality, and daytime sleepiness 8
• However, this finding contradicts the American Academy of Sleep Medicine guidelines, which do not recommend doxylamine for insomnia treatment based on more comprehensive evidence 3

Allergies

• While doxylamine is an antihistamine that can be used for allergies, specific dosing guidelines for allergy treatment were not provided in the available evidence
• The FDA-approved labeling only specifies the insomnia dosing of one tablet (25 mg) before bedtime 1

Bottom Line

For insomnia treatment, although doxylamine is available over-the-counter, clinical guidelines recommend other medications with better efficacy and safety profiles. If doxylamine is used, it should be limited to short-term treatment of occasional insomnia at the recommended dose of 25 mg taken 30 minutes before bedtime.