Central nervous system: fatigue, dizziness, drowsiness, lightheadedness, confusion, nightmares, agitation, increased anxiety, difficulty sleeping, seizures (infrequently), temporary confusion (delirium), rarely induction of hypomania and schizophrenia (stop medication immediately), extrapyramidal side effects (rarely), abuse in patients with polytoxicomania (rarely), ringing in the ears (tinnitus)
Anticholinergic: dry mouth, constipation, even ileus (rarely), difficulties in urinating, sweating, precipitation of glaucoma
Antiadrenergic: Low blood pressure, (if patient arises too fast from the lying/sitting position to standing—known as orthostatic hypotension), abnormal heart rhythms (e.g., sinus tachycardia, bradycardia, and atrioventricular block)
Allergic/toxic: skin rash, photosensitivity, liver damage of the cholestatic type (rarely), hepatitis (extremely rare), leuko- or thrombocytopenia (rarely), agranulocytosis (very rarely), hypoplastic anemia (rarely)
Others: frequently increased appetite and weight gain, rarely nausea, rarely high blood pressure. May increase or decrease liver function in some people.The side effects of low-dose doxepin for insomnia in long-term clinical trials (28 to 85 days) in adults and elderly people were as follows:

Overdose
Like other TCAs, doxepin is highly toxic in cases of overdose. Mild symptoms include drowsiness, stupor, blurred vision, and excessive dryness of mouth. More serious adverse effects include respiratory depression, hypotension, coma, convulsions, cardiac arrhythmia, and tachycardia. Urinary retention, decreased gastrointestinal motility (paralytic ileus), hyperthermia (or hypothermia), hypertension, dilated pupils, and hyperactive reflexes are other possible symptoms of doxepin overdose. Management of overdose is mostly supportive and symptomatic, and can include the administration of a gastric lavage so as to reduce absorption of the doxepin. Supportive measures to prevent respiratory aspiration is also advisable.
In Australia and the United Kingdom, the only licensed indications are in the treatment of major depression and pruritus in eczema. Research
Antihistamine
Cidoxepin is under development by Elorac, Inc. for the treatment of chronic urticaria (hives). As of 2017, it is in phase II clinical trials for this indication. The drug was also under investigation for the treatment of allergic rhinitis, atopic dermatitis, and contact dermatitis, but development for these indications was discontinued. Headache
Doxepin was under development by Winston Pharmaceuticals in an intranasal formulation for the treatment of headache. As of August 2015, it was in phase II clinical trials for this indication. Oxetorone is an antimigraine agent. Neuropathic pain
As of 2017, there was no good evidence that topical doxepin was useful to treat localized neuropathic pain. References
External links
 Media related to Doxepin at Wikimedia Commons

"Doxepin". Drug Information Portal. U.S. National Library of Medicine. "Doxepin hydrochloride". Drug Information Portal. U.S. National Library of Medicine.