How to identify a skin rash

Note whether the area is flat, raised, scaly, blistered, ring-shaped, moist or made up of small spots. Record where it began, whether it is spreading, and whether the skin feels itchy, sore, hot or swollen. New soap, cosmetics, clothing, plants, medicines, sweating or close contact can provide useful clues.

Common patterns include eczema-type inflammation, irritation or allergy from contact, heat rash in sweaty areas, fungal ringworm, scabies, psoriasis, intertrigo in skin folds and medication-related eruptions. A visual match is not a diagnosis.

Take a clear photograph in good light and note when the rash appeared. Wash gently with lukewarm water, avoid scratching, and pause newly introduced fragranced products. Keep affected folds dry and do not share towels, clothing or bedding if an infection is possible. A clinician can examine the distribution and review medicines and exposures.

Seek urgent care for trouble breathing, swelling of the lips or tongue, faintness, rapidly blistering or peeling skin, purple spots that do not fade with pressure, severe pain, or involvement of the eyes or mouth. Arrange prompt assessment if the rash is rapidly spreading, infected-looking, or follows a new medicine.

Could the distribution suggest contact, fungal, inflammatory or medication-related rash? Should I stop or continue any medicine? Would a skin scraping, swab or other examination help? What changes should prompt urgent review?