Clemastine is a first‑generation antihistamine medication commonly used to relieve symptoms of allergic reactions such as sneezing, runny nose, itchy eyes, and hives. It works by blocking histamine H₁ receptors, which helps reduce the effects of histamine, a chemical released during allergic responses. Because it also has anticholinergic properties, Clemastine can dry up mucous secretions and reduce congestion associated with allergies. The drug is typically taken orally in tablet or syrup form and is absorbed from the gastrointestinal tract after ingestion. One of its notable characteristics is that it often causes sedation or drowsiness, a common effect of first‑generation antihistamines. Clemastine has been in medical use for many decades and is available in various formulations for short‑term allergy relief. It is used for conditions like allergic rhinitis, urticaria (hives), and sometimes angioedema, where swelling occurs due to allergic triggers. The compound’s action helps control symptoms but does not cure the underlying allergic condition. Because it can cause central nervous system effects, it should be used with caution when performing tasks requiring alertness. Clemastine is metabolized in the liver and eliminated through the body over several hours after dosing. Its use has been well studied, and it remains an established option for managing allergy symptoms in clinical practice.
