Doxepin hydrochloride is a tricyclic antidepressant (TCA) used primarily for depression and anxiety at higher doses, while low-dose formulations are used for insomnia, particularly difficulty maintaining sleep. It works mainly through effects on serotonin/noradrenaline and, at low doses, histamine receptors.

Benefits:

• Helps manage depression and anxiety
• Low-dose formulations can improve sleep maintenance
• May reduce nighttime awakenings
• Can provide longer-lasting sleep without being a benzodiazepine

Off-Label Uses:

• Chronic insomnia at doses/formulations not specifically licensed for it
• Certain chronic pain and neuropathic pain conditions
• Pruritus (itching), particularly where antihistamine effects are beneficial

Potential Side Effects:

• Drowsiness and dizziness
• Dry mouth
• Constipation

Common Use: The appropriate dose varies significantly depending on whether doxepin is being used as an antidepressant or as a sleep aid.

Low-dose insomnia formulations and antidepressant doses are not interchangeable.

Note: Doxepin can cause significant sedation and should be used cautiously with alcohol and other CNS depressants.