Knowra Cetirizine Cetirizine Cetirizine is a second-generation H1 antihistamine used to relieve allergic rhinitis and hives. It causes less central nervous system sedation than many older antihistamines, though drowsiness can still occur.
Histamine H1 receptor : A G protein-coupled receptor activated by histamine, involved in allergic symptoms and wakefulness. Cetirizine relieves allergy symptoms by blocking histamine signaling at this receptor.
Allergic rhinitis : Inflammation of the nasal lining triggered by allergens, causing symptoms such as sneezing and congestion. Cetirizine can reduce sneezing, itching, and runny nose associated with this condition.
Loratadine : A second-generation H1 antihistamine used for allergic rhinitis and hives, usually with little sedation. It offers similar allergy relief and is often less sedating than cetirizine.
Antihistamine : A medicine that reduces effects mediated by histamine receptors. Cetirizine belongs to this broad drug class, specifically targeting H1 receptors.
Inverse agonist : A ligand that reduces a receptor’s baseline activity by favoring its inactive state. Cetirizine is commonly classified as an H1-receptor inverse agonist, not merely a receptor blocker.
Urticaria : A skin reaction marked by transient raised, itchy wheals, commonly called hives. Cetirizine is used to relieve itching and wheals in acute and chronic hives.
Fexofenadine : A second-generation H1 antihistamine used for allergic rhinitis and hives, with low central nervous system penetration. It generally causes less drowsiness than cetirizine, making sedation a useful comparison.
H1-receptor antagonist : A drug that blocks or reduces signaling through histamine H1 receptors. This pharmacologic class includes cetirizine and many medicines for allergic symptoms.
Blood–brain barrier : A selective interface between blood and brain tissue that limits entry of many circulating substances. Limited penetration across this barrier helps explain cetirizine’s lower, but not absent, sedation.
Chronic spontaneous urticaria : Recurrent hives lasting more than six weeks without a consistent external trigger. Guidelines commonly use second-generation H1 antihistamines, including cetirizine, as initial treatment.
Show all 22