What should you know about sudden itchy rash?

A rash limited to skin touched by a product or material may be Contact Dermatitis. A rash in sweaty or tightly covered areas may fit Heat Rash or Intertrigo. A new medicine can cause Drug Rash, which deserves medical review before the next dose unless a prescriber gives different instructions. Scaly patches may occur with Atopic Dermatitis or Psoriasis; a ring-shaped expanding rash may be Ringworm. Night-time itch or itchy close contacts raises concern for Scabies. These clues do not replace an examination.

Keep a simple timeline of foods, medicines, products, exercise, heat, travel, and illness before the rash started. Pause non-essential new cosmetics and fragranced products, wash gently, pat dry, and wear loose clothing. A cool compress can soothe irritation. Do not scratch or share towels, clothing, or bedding while an infectious cause remains possible. Avoid starting leftover antibiotics or strong steroid creams because the wrong treatment can worsen some rashes or obscure their appearance.

Call emergency services for breathing difficulty, throat or tongue swelling, faintness, or trouble swallowing. Obtain urgent assessment for a rash with fever, marked illness, skin pain, purple or bruise-like spots, blisters, peeling, mouth or eye sores, or rapid spread. Contact a clinician promptly when the rash began after a medicine, affects a young child, or continues despite removing a suspected trigger.

Does the distribution suggest contact, heat, infection, or a medicine reaction? Should I continue each current medicine? Is the rash contagious, and what hygiene steps are needed? What changes would mean I need urgent review?