Doxepin is a tricyclic antidepressant (TCA) with strong sedative properties. It is prescribed for the treatment of depression, anxiety disorders, insomnia, and related conditions. Doxepin works by increasing the levels of certain neurotransmitters in the brain—particularly serotonin and norepinephrine—helping to improve mood and relieve symptoms of depression. Thanks to its calming effects, it is also used to manage sleep disturbances, especially in patients with coexisting mood disorders.