Chloropyramine

What it is

Chloropyramine is a first-generation antihistamine that blocks H1 histamine receptors and also has anticholinergic activity. It relieves allergic symptoms such as itching, rash, hives, runny nose and watery eyes. Unlike newer antihistamines it crosses into the brain readily, which accounts for both its calming effect and its side effects.

Used for

• Allergy

What to know while taking it

It is taken with food, which reduces stomach irritation. Drowsiness is common and often pronounced, so driving and any task needing alertness should be avoided until the individual response is known. Alcohol must not be combined with it, as the two together deepen sedation and impair judgement well beyond what either does alone; sleeping tablets, opioid painkillers and other sedatives do the same. The anticholinergic action can cause dry mouth, blurred vision, constipation and difficulty passing urine, which older adults notice most.

When to see a doctor

See a doctor if urine becomes difficult to pass, vision blurs persistently, confusion or unusual agitation appears, or sedation is severe. Swelling of the face, lips or throat and trouble breathing need urgent care.

Worth knowing

• Causes drowsiness
• Care when driving
• Do not combine with alcohol