Knowra Antihistamine Antihistamine An antihistamine is a drug that blocks or reduces histamine signaling. These drugs commonly relieve allergy symptoms and are also used for conditions such as motion sickness and insomnia.
Histamine : A signaling molecule involved in immune responses, stomach acid secretion, and brain activity. Antihistamines reduce effects produced when histamine activates its receptors.
Allergy : An immune response to a normally harmless substance that causes symptoms or tissue inflammation. Antihistamines commonly treat symptoms produced during allergic reactions.
Allergic rhinitis : Inflammation of the nasal lining caused by an allergic response, often producing sneezing, itching, and congestion. Oral and nasal antihistamines can relieve sneezing, itching, and runny nose.
Corticosteroid : A steroid hormone or synthetic drug that broadly alters inflammation and immune activity. Intranasal corticosteroids often control nasal congestion better than oral antihistamines.
Sedation : A reduction in alertness or responsiveness caused by a drug or medical intervention. Sedation is a common effect of first-generation antihistamines that enter the brain.
Histamine receptor : A cell-surface protein that responds to histamine; the main types include H1, H2, H3, and H4 receptors. Most allergy medicines act by blocking H1 receptors, while other antihistamines target different types.
Allergen : A substance that triggers an allergic immune response in a susceptible person. Allergens initiate the responses whose histamine-related symptoms antihistamines can reduce.
Urticaria : A skin condition marked by transient, itchy raised welts known as hives. H1 antihistamines are commonly used to control itching and wheals.
Epinephrine : A hormone and medication that rapidly affects heart, airway, and blood-vessel function. Epinephrine, not an antihistamine, is the first-line emergency treatment for anaphylaxis.
Antihistamine toxicity : Harmful effects caused by excessive exposure to antihistamine drugs. Overdose can cause serious neurological and cardiovascular effects, especially with older agents.
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