Hives after taking antibiotics

Hives are itchy, raised areas that can appear suddenly and change location. An antibiotic can trigger an immediate allergic reaction, but an infection being treated can also cause a rash. Some rashes that follow antibiotics are not hives: a fixed, painful, blistering, or peeling rash needs prompt assessment. The timing, antibiotic name, dose, other medicines, and the illness being treated help a clinician judge the cause. Never label yourself as allergic based only on a description if medical review is available, but do treat a suspected reaction seriously.

If hives start after a dose, contact the prescriber or pharmacist for advice before taking the next dose. Do not take an extra dose, switch antibiotics, or use leftover medicine. If a clinician tells you to stop it, ask how the original infection should be treated. Keep the packet or a photo of its label, and write down when the dose and rash occurred. A suitable antihistamine may ease itching, but use one recommended for the person’s age, pregnancy status, and health conditions. Related infections treated with antibiotics include cellulitis, chlamydia, gonorrhoea, and Helicobacter Pylori Infection.

Call emergency services immediately for difficulty breathing, wheezing, throat or tongue swelling, faintness, or collapse. Seek urgent assessment for widespread blistering or peeling, painful skin, sores in the mouth or eyes, fever with a rapidly spreading rash, or severe weakness. Even mild hives should be reported because the medicine may need review.

Ask: Should I take another dose? Is this likely to be an allergy? What alternative treats the infection? Should this antibiotic be recorded as a suspected reaction?