Severe skin rash: what to know

Rash describes a visible change rather than one diagnosis. Redness, bumps, plaques, blisters, scaling, swelling, peeling, or oozing can appear in different combinations. An itchy rash may occur with atopic dermatitis, contact dermatitis, heat rash, scabies, or ringworm. A rash after a new medicine can be a drug eruption. Moisture and friction in skin folds may cause intertrigo, while psoriasis can produce well-defined, scaly areas. The location, speed of spread, itch or pain, recent products, medicines, travel, and contact with others help a clinician narrow the cause. A rash itself does not establish which condition is responsible.

Stop newly introduced fragranced products and avoid scratching, scrubbing, or applying several medicated creams at once. Use lukewarm water, pat the skin dry, and choose loose, breathable clothing. Keep a list of new medicines, supplements, cosmetics, detergents, foods, and possible contacts with contagious conditions. Take clear photographs as the rash changes. A clinician may need to examine the skin closely or test a sample; treatment depends on the cause, so an old prescription may be unsuitable. Related information includes [Atopic Dermatitis](/conditions/atopic-dermatitis/), [Contact Dermatitis](/conditions/contact-dermatitis/), and [Drug Rash](/conditions/drug-eruption/).

Get urgent help for a rash with trouble breathing, swelling of the lips or tongue, faintness, widespread blistering, skin peeling, painful raw skin, or sores involving the eyes or mouth. Seek prompt medical review for fever, marked pain, pus, rapidly spreading redness, or a rash soon after starting a medicine. People with weakened immunity, infants, and those who are pregnant may need earlier advice.

What features point toward the likely cause? Could a medicine, product, infection, or skin-fold irritation be involved? Do I need a swab, scraping, or other test? Which treatments should I use or avoid, and what warning signs require urgent reassessment?