Heat rash all over the body

Heat rash often consists of small red or skin-coloured bumps with prickling or itch in areas where sweat is held against the body. If the eruption covers much of the skin, check for a clear heat trigger, recent new products or medicines, fever, pain, blisters and breathing symptoms. Skin bumps, skin redness and skin rash are descriptions rather than diagnoses.

Move to a cool place, loosen clothing, rinse gently with lukewarm water and pat dry. Pause exercise and avoid hot rooms, direct sun, scratching, fragranced products and thick occlusive creams. Sip fluids if you are awake and able to drink. Keep the skin uncovered where practical and use light breathable fabric. A bland moisturiser may help dry areas; ask a clinician before using emollient therapy over a widespread active eruption.

Contact a clinician promptly when the rash is widespread, new without a clear heat exposure, persistent, painful, blistered, bruised-looking, or accompanied by fever. Seek emergency help for confusion, fainting, severe weakness, trouble breathing, facial or tongue swelling, repeated vomiting, or rapidly worsening skin changes. Widespread symptoms should not be dismissed as heat rash without considering other causes.

Tell your doctor when the rash began, where it started, recent heat or exercise, medicines, products and associated symptoms. Ask whether you need an examination, which skin care is suitable, and whether a topical corticosteroid has any role.