What should you know about chronic heat rash?

Heat rash, also called prickly heat, occurs when sweat cannot move freely through the skin. It may cause tiny bumps, prickling, itching, or redness in covered areas such as the neck, chest, back, groin, or skin folds. Hot weather, heavy sweating, tight clothing, occlusive products, and prolonged dampness can keep the cycle going. A rash that remains after the skin is cool may instead be another skin condition, especially if it is painful, crusted, spreading, or not limited to heat-exposed areas.

Move to a cooler environment, take lukewarm showers, pat the skin dry, and choose loose breathable clothing. Change damp clothes promptly and keep folds dry without vigorous rubbing. Avoid thick oily products over affected areas unless a clinician recommends them; a suitable emollient may help when surrounding skin is dry. A clinician may consider a topical corticosteroid for selected inflammation, but the product, strength, and duration should match the body site.

Arrange medical review if the rash does not settle after cooling measures, returns frequently despite preventing overheating, or develops pus, blisters, open skin, increasing pain, or marked swelling. Seek urgent help for a widespread rash with breathing difficulty, facial swelling, faintness, or fever. Infants, older adults, and people who cannot regulate body temperature should be assessed early when a heat-related rash is persistent.

Ask whether the appearance fits heat rash or another rash, which products are safe on the affected site, and how to prevent recurrence in hot or humid conditions. If a corticosteroid is suggested, ask where to apply it, how often to use it, and which changes should prompt a follow-up.