spec sheet10 rows
Doxylamine is a first-generation H1 antihistamine marketed over the counter as a hypnotic and combined into nighttime cold and flu preparations. It produces sedation through histamine H1 receptor blockade and, like related ethanolamine antihistamines, is strongly anticholinergic, so that supratherapeutic doses can cause an unpleasant deliriant state with somnolence, agitation, hallucinations, mydriasis, and tachycardia. A characteristic and clinically important feature of doxylamine overdose is a comparatively high incidence of rhabdomyolysis, which can lead to acute kidney injury requiring haemodialysis; the amount ingested is the principal predictor, with risk rising steeply above roughly 20 mg per kilogram. Management centres on aggressive hydration, electrolyte monitoring, and support for renal and, less commonly, hepatic and pancreatic complications.
- Short-term over-the-counter sleep aid
- Relief of runny nose and sneezing in cold and flu combinations
- Used with pyridoxine (vitamin B6) for nausea and vomiting of pregnancy
- Overdose distinctively causes rhabdomyolysis and renal injury
- Next-day sedation and grogginess
- Dry mouth, blurred vision, constipation, urinary retention
- Confusion and delirium at high doses
- Dangerous overheating and rapid heartbeat in overdose
Mechanism
Doxylamine is a competitive at H1 receptors; because it crosses the , blocking central H1 receptors causes the sedation and drowsiness it is used for. It is also a competitive antagonist at receptors (the same receptors acetylcholine normally activates for memory, attention, and the parasympathetic 'rest and digest' functions). Blocking those muscarinic receptors is what dries secretions and, at high doses, produces the central anticholinergic delirium; the brain's cholinergic signaling for coherent thought and memory is essentially shut down.
receptor fingerprint
H1 receptorAntagonist (inverse agonist)
receptors (M1-M5)Antagonist
Safetyrisks and cautions, not medical advice
At recreational (high) doses doxylamine causes an anticholinergic delirium that is dangerous and, by almost every honest account, deeply unpleasant rather than fun; realistic hallucinations mistaken for reality, confusion, and memory loss, along with the classic toxidrome (blurred vision, flushing, dangerous overheating, dry mouth), plus racing heart, urinary retention, seizures, and rarely death. High doses can also cause rhabdomyolysis (muscle breakdown that can injure the kidneys) even without warning. Do not combine it with other anticholinergics or antihistamines; that stacks the anticholinergic burden and multiplies the danger, and long-term or elderly use carries associations with dementia risk. Not medical advice.
Subjective profileweighing the evidence above
Works for an occasional rough night and nothing more; the anticholinergic load leaves next-day grogginess and it is a poor habit to build. Large doses do not deepen sleep, they produce an ugly delirium, and distinctively they can cause rhabdomyolysis and kidney injury.
Resources
This entry is here for reference.
Research
- 2002first citedAcute pancreatitis and acute renal failure complicating doxylamine succinate intoxication.
- 2025most recentOver-the-counter Psychosis: A Systematic Review of the Misuse of Antihistamines, Cough Medicine…
- 1.Classics in Chemical Neuroscience: Deliriant Antihistaminic Drugs
- 2.When Overdose of Doxylamine Leads to Severe Rhabdomyolysis and Renal Failure That Requires Hemodialysis: A Case Report and Literature Review
- 3.The associative factors of delayed-onset rhabdomyolysis in patients with doxylamine overdose.
- 4.Risk factors for rhabdomyolysis following doxylamine overdose.
- 5.Acute pancreatitis and acute renal failure complicating doxylamine succinate intoxication.
- 6.Over-the-counter Psychosis: A Systematic Review of the Misuse of Antihistamines, Cough Medicines, and Decongestants and the Risk of Developing Psychosis.
6 listed here; entry last updated August 2026
Reviews
My notesprivate to this device
FAQ
Is doxylamine safe as a sleep aid?
At the labeled over-the-counter dose it is generally used for short-term sleep, though it commonly leaves next-day grogginess and dry mouth. It is not meant for long-term nightly use, and older adults are more sensitive to its anticholinergic effects.
Why do people call it a deliriant?
Because it blocks muscarinic acetylcholine receptors. At high doses that anticholinergic action produces a confused, hallucinatory delirium, the same class of effect as diphenhydramine and the belladonna plants.
Is the high enjoyable?
By nearly all accounts, no. The experience is typically frightening and confusing rather than euphoric, with realistic hallucinations mistaken for reality, memory gaps, and a real risk of medical emergency.
Adverse effects
- Next-day sedation and grogginess
- Dry mouth, blurred vision, constipation, urinary retention
- Confusion and delirium at high doses
- Dangerous overheating and rapid heartbeat in overdose