Antihistamines: which kind, and why does it matter?

Key points

• Antihistamines ease sneezing and a runny nose, but are usually less effective for a blocked nose.
• Older, sedating antihistamines cross into the brain; non-sedating ones barely do.
• In anaphylaxis an antihistamine comes after initial stabilisation — it never replaces adrenaline.
• STOPP: avoid first-generation antihistamines in older people when safer ones will do.