Chlorphenamine

What is Chlorphenamine used for?

Chlorphenamine (brand name Piriton) is a first-generation antihistamine that blocks histamine H1 receptors in the body, relieving allergy symptoms such as runny nose, sneezing, itchy skin and hives. It works quickly but tends to cause drowsiness because it crosses the blood-brain barrier.

How to take Chlorphenamine and adjust the dose

Adults and adolescents over 12: typically 4mg every 4–6 hours, not exceeding 24mg in 24 hours. Children's doses must be adjusted by age/weight — consult a doctor or pharmacist; not suitable for newborns or premature infants. Elderly patients are more sensitive to side effects (drowsiness, fall risk) and should start with a lower dose. Follow the package insert or pharmacist's instructions if using syrup.

Chlorphenamine side effects

• Common: drowsiness, dizziness, constipation, blurred vision, dry mouth/throat
• Serious (rare): severe allergic reaction, irregular heartbeat, confusion (more common in elderly)

Who should not take Chlorphenamine?

• Known allergy to chlorphenamine
• Narrow-angle glaucoma
• Peptic ulcer
• Prostatic hypertrophy
• Severe hypertension or severe coronary artery disease
• Consult a doctor before use during pregnancy/breastfeeding
• Avoid combining with alcohol, sedatives, or MAO inhibitors