The rash often looks red, but this may be less obvious on brown or black skin. The symptoms of heat rash are often the same in adults and children. It can appear anywhere on the body and spread, but it cannot be passed on to other people.

How do you treat heat rash from spreading?

Bathe or shower in cool water with nondrying soap, then let your skin air-dry instead of toweling off. Use calamine lotion or cool compresses to calm itchy, irritated skin. Avoid using creams and ointments that contain petroleum or mineral oil, which can block pores further.

What can be mistaken for heat rash?

Polymorphic light eruption can be easily mistaken for heat rash (prickly heat). Prickly heat is caused by warm weather or overheating, rather than sunlight or UV light. The skin in prickly heat does not "harden" or desensitise, as it can do in polymorphic light eruption.