What should you know about a red sandpaper-like rash?

Fine rough bumps may follow sweating and blocked sweat ducts, while itch after a new soap, fabric, adhesive, or cosmetic can fit contact dermatitis. Atopic dermatitis may produce dry, intensely itchy patches. Psoriasis can form thicker, well-defined scaly areas. A ring-shaped, expanding patch may fit ringworm; marked nighttime itch or affected household contacts can point toward scabies. A new medicine can also trigger a drug rash. The appearance alone cannot confirm a cause.

Keep the area cool, wash gently with lukewarm water, and use a fragrance-free moisturiser. Stop any newly introduced product touching the rash and avoid scratching, tight clothing, and vigorous rubbing. Take a clear photograph and note when it began, where it started, recent medicines, travel, heat exposure, and possible contact with an affected person. A clinician can examine the pattern and decide whether testing or targeted treatment is needed.

Seek urgent medical help for trouble breathing, swelling of the lips or face, faintness, blistering, skin peeling, purple or non-blanching spots, or sores involving the eyes or mouth. Arrange prompt assessment if the rash is rapidly spreading, painful, warm and swollen, associated with fever, or producing pus. Persistent, recurrent, or unexplained rash also deserves a clinical review.

Could the distribution and texture fit eczema, contact dermatitis, heat rash, psoriasis, ringworm, scabies, or a medicine reaction? Do I need a skin scraping, swab, or other examination? Which products should I pause, and what symptoms would mean I should return quickly?