Hives caused by medication: what should you know?

Hives can follow a newly started medicine, a dose change, or sometimes a medicine taken before without a problem. The trigger may be the active ingredient or another component, and an infection being treated can also cause a rash. Welts may be itchy or not itchy and may move across the skin. Swelling of the face, lips, or tongue can occur alongside hives as angioedema. A fixed rash with peeling, blisters, mouth sores, or marked pain needs a different level of concern.

Write down the medicine name, dose, start date, last dose, and all other tablets, supplements, and topical products. Photograph the rash if it changes quickly. Contact the prescriber or pharmacist promptly for advice about the suspected medicine; do not re-challenge yourself or stop an essential prescription without guidance unless emergency services tell you to. An antihistamine treatment may be considered for hives, while other treatment depends on severity and examination.

Call emergency services immediately for breathing difficulty, wheezing, throat tightness, dizziness, collapse, or swelling of the tongue or mouth. Get urgent assessment for rapidly worsening hives, extensive skin peeling, blisters, painful skin, or sores affecting the eyes or mouth. Tell every future clinician about the suspected reaction and keep the medicine packaging if available.

Could this be a reaction to the medicine or to the illness being treated? Should I take the next dose? Which alternatives are appropriate? Should this suspected reaction be recorded in my medical notes? What symptoms would require emergency help?