A sedating antihistamine · Written by the Lyng Pharmacy team, based on NHS and BNF guidance · Updated August 2026
Also sold asPiriton
Type of medicineSedating antihistamine
Available asTablets, oral solution, injection
How you get itGeneral sale and pharmacy
Chlorphenamine is an older, sedating antihistamine. Non-drowsy options have replaced it for everyday hay fever, but it still has a place — particularly for night-time itching, and as an adjunct in allergic reactions.
What it is used for
Allergic reactions, hives, insect bites and stings, and itching that disturbs sleep. It is also used alongside emergency treatment in allergic reactions.
Antihistamines are not a treatment for anaphylaxis. If there is throat swelling, breathing difficulty, dizziness or collapse, use an adrenaline auto-injector if available and call 999 — do not give an antihistamine and wait.
Drowsiness
Chlorphenamine causes marked drowsiness in most people, which can persist into the next day. Do not drive or operate machinery until you know how it affects you — driving while impaired is an offence.
Avoid alcohol and other sedating medicines.
It is not recommended as a sleep aid for children, and paradoxical excitement can occur in young children rather than sedation.
Who should take care
Older adults — sedating antihistamines increase confusion and fall risk, and are generally best avoided
Glaucoma
Prostate problems or difficulty passing urine
Epilepsy
Severe liver disease
Other effects: dry mouth, blurred vision, constipation and difficulty passing urine.
For everyday hay fever, a non-drowsy antihistamine such as loratadine or cetirizine is usually the better choice — ask us.
Always read the label. This page is general information, not advice for your situation. Doses, warnings and interactions differ between products and between people. Check the leaflet inside your medicine, and ask our pharmacist if anything is unclear — that conversation is free and takes two minutes.
Questions about Chlorphenamine?
1 Lyng Lane, West Bromwich B70 7RW · Mon–Fri 8:30am–6pm, Sat 9am–1pm · 0121 500 5756
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