chlorpheniramine

Chlorpheniramine is a first‑generation antihistamine used to relieve symptoms of allergic rhinitis, conjunctivitis, urticaria, and other itching conditions. It functions as a competitive antagonist at the histamine H1 receptor, helping to reduce sneezing, runny nose, itchy eyes, and skin itching.

It is commonly formulated as oral tablets, capsules, or syrup and may be included in combination products with decongestants or analgesics for cold and flu relief. Chlorpheniramine is generally taken several times daily, with dosing depending on age and product formulation.

Common indications include seasonal and perennial allergic symptoms, as well as mild dry coughs associated with postnasal drip. It is not a substitute for asthma or other chronic conditions and should be used according to label directions or a clinician’s advice. It can cause drowsiness and impaired performance, so activities requiring alertness should be approached with caution.

Adverse effects are typical of first‑generation antihistamines and include drowsiness, dry mouth, blurred vision, constipation, and urinary retention, particularly in older adults. Palpitations or confusion may occur rarely. Chlorpheniramine can interact with alcohol and other central nervous system depressants, increasing sedative effects. Caution is advised with monoamine oxidase inhibitors and other anticholinergic drugs.

Pharmacokinetics: chlorpheniramine is well absorbed after oral intake, with onset within 15–60 minutes and peak effects in 1–3 hours; the half‑life ranges roughly from 12 to 24 hours in adults, with hepatic metabolism and renal excretion.

Special considerations: use in pregnancy or breastfeeding should be discussed with a clinician, and use in young children or the elderly requires extra caution due to anticholinergic risks.