What should you know about really bad heat rash?

Heat rash, also called prickly heat, develops when trapped sweat irritates or blocks the ducts that carry sweat to the skin surface. It may look like clusters of tiny bumps, redness, or clear fluid-filled spots, with prickling, itching, or stinging. It commonly affects covered or sweaty areas such as the neck, chest, back, groin, and skin folds. Widespread redness, marked tenderness, pus, fever, or increasing warmth can point to another problem or a secondary infection rather than uncomplicated heat rash.

Move to a cool, shaded or air-conditioned place and remove tight or damp clothing. Rinse with cool—not icy—water, then pat the skin dry. Wear loose, breathable clothing and keep affected folds dry. Avoid heavy oils, fragranced products, vigorous scrubbing, and scratching, which can worsen blocked ducts and broken skin. A plain moisturising barrier may help reduce friction; see Emollient Therapy for general skin-barrier care. A clinician may consider Topical Corticosteroids when inflammation is significant, but treatment depends on the appearance and location.

Arrange medical assessment if the rash is spreading, very painful, blistering, draining, or associated with fever, chills, dizziness, vomiting, confusion, or trouble breathing. Seek urgent help for confusion, fainting, severe weakness, or hot skin with a very high temperature because these can signal heat illness. If cooling and gentle care do not start improving the rash, a clinician can check whether infection, eczema, or another rash is responsible.

Ask whether the pattern fits heat rash, whether infection is present, and which products are suitable for the affected area. Mention recent heat exposure, sweating, new medicines or creams, and any fever or drainage.