Heat rash due to fever: what to know

Heat rash is caused by sweat becoming trapped, so sweating during a fever can contribute, particularly under blankets or close-fitting clothing. Fever itself is not proof that a rash is heat rash. Viral illnesses, medicine reactions and infections can also cause a rash. Consider when the fever and spots began, whether the skin is prickly or painful, and whether the rash fades or changes with cooling.

Keep the room comfortably cool, use light breathable clothing and avoid piling on blankets. Offer appropriate fluids if the person can drink, follow clinician or package advice for fever care, and do not put ice directly on the skin. Clean and dry sweaty areas gently. Avoid applying new fragranced products or [Topical Corticosteroids](/treatments/medical-dermatology/topical-corticosteroids/) unless a clinician recommends them; [Emollient Therapy](/treatments/medical-dermatology/emollient-therapy/) may suit dry skin but does not explain an unexplained fever.

Contact a clinician promptly for fever with a new rash, especially when the person is a baby, pregnant, immunocompromised or taking a new medicine. Seek urgent help for breathing trouble, swelling of the lips or face, confusion, severe headache, stiff neck, faintness, purple or bruise-like spots, or rapidly worsening illness. A [Skin Rash](/symptoms/skin-rash/) with fever needs context rather than a heat-rash assumption.

Ask whether the fever and rash may be connected, whether any medicine should be paused, and what warning signs to monitor. Record the temperature pattern, medicines given, exposures, rash location and whether [Skin Redness](/symptoms/skin-redness/) or [Skin Bumps](/symptoms/skin-bumps/) are changing.