Exanthematous rash: what to know

The spots may be flat or slightly raised and often start on the trunk before extending to the arms, legs or neck. Itching can occur, but the rash may also be mild and feel otherwise well. Recent fever, sore throat, a new medicine, travel, new products or contact with an ill person are useful clues. The appearance alone cannot distinguish a drug eruption from viral illness, eczema, psoriasis, heat rash, fungal infection or scabies.

Take clear photographs and note when the rash began, where it started and whether it is spreading. List all medicines, supplements and recent illnesses for the clinician. Use lukewarm water and an unperfumed moisturiser, wear loose clothing and avoid scratching. Do not start steroid cream or stop a prescribed medicine without advice, because treatment depends on the cause and some rashes are infectious.

Seek emergency care for breathing difficulty, facial or tongue swelling, faintness, skin pain, blistering, peeling, or sores affecting the mouth, eyes or genitals. Arrange prompt assessment for a rapidly spreading rash, high fever, marked illness or a rash after a new medicine. A child, pregnant person or person with reduced immunity may need earlier advice.

Ask what diagnoses fit the pattern, whether you need testing, how to reduce itching safely, and whether you should avoid work, school, swimming pools or close contact while the cause is being clarified.