Rash appearing after fever: what should you know?

Write down when the fever started, when it ended, and when spots appeared. A spreading rash after a respiratory illness may be viral; chickenpox often develops itchy spots that become blisters and crusts. Other explanations include a medicine reaction, heat irritation, or a bacterial skin infection. Look for itching, pain, warmth, swelling, blisters, peeling, mouth sores, or eye involvement. A rash appearing after fever does not by itself establish a diagnosis.

Take a clear photograph and mark the edge of a red area if it is expanding. Offer frequent drinks and light clothing, and use gentle, fragrance-free washing. Avoid starting or stopping prescription medicine without advice; record every recent medicine, supplement, and new food or product. Keep a child away from school or group activities until a clinician advises that an infectious cause is unlikely or precautions are clear.

Seek emergency care for breathing trouble, facial swelling, collapse, confusion, a stiff neck, or a purple rash that does not fade under pressure. Arrange prompt assessment for skin pain, rapid spread, pus, extensive blistering, peeling, mouth or eye sores, renewed fever, or a person who is difficult to wake. Babies and people with reduced immunity need a lower threshold for medical review.

Does the sequence of fever followed by rash fit a viral illness? Could a medicine reaction be involved? Is the person contagious, and what precautions are appropriate? What changes should prompt same-day review?