Rash over the body: what to know

Consider when the rash started and whether a new medicine, food, detergent, cosmetic, or material came first. Contact Dermatitis tends to appear where an irritant or allergen touched. Atopic Dermatitis often causes itchy, dry, inflamed areas. Heat Rash favors hot, sweaty, covered skin. Scabies can cause intense itch, often worse at night, with close contacts sometimes itching too. Ringworm may form expanding, scaly patches. Psoriasis can produce persistent, sharply defined scaly plaques. These clues are useful, but they do not replace an examination.

Take photographs in good light and record new products or medicines. Wash gently with lukewarm water, use a plain fragrance-free moisturiser on dry skin, and wear loose clothing. Keep cool and avoid scratching, scrubs, and essential oils. Do not stop a prescribed medicine without advice, but contact the prescriber promptly if the rash began after a new drug. Avoid sharing towels or clothing until an infectious cause has been considered.

Get prompt medical assessment for a widespread rash that is new, persistent, rapidly spreading, or associated with fever, feeling very unwell, joint pain, or skin tenderness. Seek emergency help for breathing difficulty, swelling of the lips or tongue, faintness, purple or non-blanching spots, or blistering and peeling skin.

What features make one cause more likely? Could a medicine or contact exposure be involved? Do I need testing, treatment for itch, or precautions for people at home?