Flat red rash: what to know

A rash may be itchy, sore, warm, scaly, dry or smooth. Contact Dermatitis can follow exposure to a product or substance. Atopic Dermatitis often causes dry, itchy inflamed skin. Heat Rash favours hot, sweaty areas, while Intertrigo affects skin folds. Psoriasis may form well-defined scaly plaques; Ringworm often expands in a ring-like pattern; Scabies commonly causes intense itch and may affect household contacts.

A Drug Rash can begin after a new medicine, including one that has been taken before. The appearance alone cannot confirm the cause, so list new medicines, products, foods, travel, illness and exposures for the clinician.

Wash gently with lukewarm water, pat dry and use an unfragranced moisturiser. Stop newly introduced cosmetics or detergents until the cause is clearer, and keep a note of the rash's spread and symptoms. Avoid scratching; cool compresses and loose clothing may reduce irritation. Do not stop a prescribed medicine without advice, but contact the prescriber promptly if the rash followed a new drug.

Treatment depends on the diagnosis. A clinician may consider Atopic Dermatitis, Contact Dermatitis, Drug Rash, Heat Rash, Intertrigo, Psoriasis, Ringworm or Scabies based on the pattern and history.

Get urgent medical help if a rash spreads rapidly, blisters, peels, becomes very painful, involves the eyes or mouth, or appears with fever or feeling very unwell. Emergency care is needed for facial swelling, breathing difficulty, faintness, or a rash with purple or dark spots that do not fade when pressed. These features can signal a serious reaction and should not be monitored at home.

Ask what pattern the rash follows, whether a medicine or contact exposure is relevant, whether testing is needed, which products are safe while it settles, and what worsening sign should prompt urgent reassessment.