What to know about a bad rash

Rashes can reflect irritation, allergy, inflammation, infection, heat, or a reaction to medicine. Appearance alone may not identify the cause. Location, itch or pain, recent products, medicines, illness, travel, and contact with affected people all help narrow it down. Atopic dermatitis often presents with itchy, dry or inflamed skin, while contact dermatitis commonly appears where a trigger touched the skin. Ringworm can present as a scaly expanding patch, and scabies commonly causes marked itching with small bumps.

Stop any new cosmetic, fragrance, detergent, or topical medicine that may have triggered the change. Keep the area cool, rinse gently with lukewarm water, pat dry, and choose loose clothing. A plain fragrance-free moisturiser can support dry, unbroken skin. Avoid scratching, hot showers, harsh scrubs, and sharing towels. Do not apply leftover antibiotic, steroid, or antifungal cream unless a clinician has identified what is being treated, because the wrong product may mask or aggravate some rashes.

Call emergency services for trouble breathing, faintness, or swelling of the lips, tongue, face, or throat. Seek urgent assessment for widespread blistering or peeling, purple spots that do not fade with pressure, severe skin pain, eye or mouth involvement, fever with a rapidly spreading rash, or a rash that began after a new medicine. Arrange a routine appointment if it persists, repeatedly returns, weeps, crusts, or disrupts sleep.

Ask which diagnosis fits the pattern, whether any product or medicine should be stopped, whether testing is useful, and which treatment is safe for the affected body site. Photos showing how the rash changed and a list of recent medicines and skin products can make the consultation more informative.