Doxepin low-dose (insomnia)

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What it isLow-dose doxepin 3/6 mg, a tricyclic whose H1 antagonism treats sleep-maintenance insomnia.

Why this oneAt insomnia exposure it acts mainly as an antihistamine, with less antimuscarinic burden than antidepressant-dose doxepin.

What limits itNext-day sedation and additive CNS depression can impair driving; the antidepressant suicidality warning remains.

FDA-approved for

insomnia (sleep maintenance) (2010)

FDA label

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FDA dosing	Population	Start	Target	Max
Insomnia (sleep maintenance)	Adults	6 mg once daily (3 mg may be appropriate)	6 mg QHS	6 mg/day
Insomnia (sleep maintenance)	Elderly (≥65 y)	3 mg once daily	3 mg QHS (may increase to 6 mg)	6 mg/day

Renal Undefined (not studied; not expected to significantly alter concentrations)

Hepatic Initiate at 3 mg (hepatic impairment); monitor for daytime effects

Instructions

Take within 30 minutes of bedtime
Do not take within 3 hours of a meal
Total dose should not exceed 6 mg/day
With cimetidine, max dose 3 mg

Contraindications

Co-administration with monoamine oxidase inhibitors (MAOIs) — do not administer if taking MAOIs or used within the past two weeks
Untreated narrow angle glaucoma or severe urinary retention

Cautions

Evaluate for comorbid diagnoses if insomnia persists after 7-10 days
Abnormal thinking/behavioral changes including sleep-driving and hallucinations
Worsening of depression or suicidal thinking
CNS-depressant effects; avoid hazardous activities; do not use with alcohol
Additive effects with CNS depressants/sedating antihistamines
Not recommended in severe sleep apnea

Adverse reactions

Somnolence/sedation
Nausea
Upper respiratory tract infection/nasopharyngitis

Pregnancy Epidemiologic data have not established increased risk of major birth defects; third-trimester TCA exposure risks poor neonatal adaptation

Lactation Doxepin present in human milk; excess sedation, respiratory depression, hypotonia reported — breastfeeding not recommended

⚠ BOXED WARNING