doxylamine

General information

• Primary label indications include: OTC sleep aid (product-dependent).
• Class: Adjunctive therapy
• Common US brands: UNISOM
• Typical dose range: OTC sleep aid labeling is product-dependent; one common direction is 25 mg once nightly about 30 minutes before bed.
• Therapeutic drug monitoring not routinely recommended.
• Last reviewed: 2025-12-30

Dosing & forms

• Forms/strengths: OTC sleep aid tablets are commonly 25 mg (product-dependent); label dosing is typically once nightly.; Diclegis delayed-release tablets contain doxylamine succinate 10 mg and pyridoxine HCl 10 mg (label).
• Frequency: OTC sleep aid labeling is product-dependent; one common direction is 25 mg once nightly about 30 minutes before bed.
• Typical range: OTC sleep aid labeling is product-dependent; one common direction is 25 mg once nightly about 30 minutes before bed.

Mechanism (brief)

First-generation antihistamine (H1 antagonist) with sedating and anticholinergic effects; OTC sleep aid and antiemetic ingredient (doxylamine/pyridoxine).

Metabolism & Half‑life

• Metabolism: Hepatic
• Half‑life: Single-dose mean 10 h; Single-dose range 10–15 h

Therapeutic Drug Monitoring (TDM)

Recommended: No

Monitoring highlights

• Sedation and next-day impairment (falls risk, driving safety).
• Anticholinergic effects (constipation, urinary retention, blurred vision).
• Confusion or delirium risk in older adults and polypharmacy (Beers).
• Avoid duplicate sedatives and document a stop plan if nightly use develops.

Sources

• Doxylamine succinate (OTC sleep aid) tablets label — DailyMed (2025)
• Diclegis (doxylamine/pyridoxine) delayed-release tablets label — DailyMed (2024)
• Doxylamine (StatPearls) — StatPearls Publishing (NCBI Bookshelf) (2025)
• Clinical Practice Guideline for the Pharmacologic Treatment of Chronic Insomnia in Adults: An American Academy of Sleep Medicine Clinical Practice Guideline — Journal of Clinical Sleep Medicine (2017)
• 2023 American Geriatrics Society Updated Beers Criteria for Potentially Inappropriate Medication Use in Older Adults — Journal of the American Geriatrics Society (2023)