Knowra Diphenhydramine Diphenhydramine Diphenhydramine is a first-generation antihistamine used for allergy symptoms, motion sickness, and short-term sleep problems. Its effects include sedation and anticholinergic actions.
Histamine H1 receptor : A receptor that mediates many histamine effects, including itching, vascular changes, and wakefulness. Diphenhydramine blocks this receptor to reduce allergic symptoms and promote sleepiness.
Allergic rhinitis : Inflammation of the nasal lining caused by an allergic response, often producing sneezing and congestion. Diphenhydramine can relieve sneezing and runny nose, though newer antihistamines often cause less sedation.
Cetirizine : A second-generation H1 antihistamine used for allergic rhinitis and hives, with less central sedation than older agents. It often controls allergy symptoms with less drowsiness than diphenhydramine.
Antihistamine overdose : Toxic exposure to antihistamine medicines that can cause severe neurological, cardiac, and anticholinergic effects. Large diphenhydramine doses can cause delirium, seizures, abnormal heart rhythms, and death.
Blood–brain barrier : A selective interface that regulates movement of substances between the bloodstream and the brain. Diphenhydramine crosses this barrier, contributing to central sedation and impaired alertness.
Urticaria : A skin reaction marked by transient, itchy raised welts known as hives. Blocking H1 receptors can reduce the itching and welts associated with hives.
Loratadine : A second-generation H1 antihistamine used for allergic symptoms that usually causes little sedation at recommended doses. It offers a less sedating option for routine allergy treatment.
Anticholinergic syndrome : A toxidrome caused by excessive muscarinic blockade, often involving confusion, dry skin, dilated pupils, and urinary retention. Severe diphenhydramine toxicity can produce this characteristic cluster of symptoms.
Anticholinergic : Describing a substance that reduces signaling by acetylcholine at muscarinic receptors. Diphenhydramine’s antimuscarinic activity causes effects such as dry mouth and blurred vision.
Motion sickness : Nausea and related symptoms triggered by conflicting sensory signals during movement. Diphenhydramine can reduce motion-sickness symptoms, but its drowsiness may impair activities.
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