Symptoms of Heat Rash

Symptoms of heat rash depend on how deep in the skin the sweat is trapped. The rash usually appears in areas where skin is covered or rubs together.

Common symptoms

• Tiny red bumps, often in clusters
• Clear, small, fluid-filled blisters that break easily
• Prickling, stinging or itching, especially when sweating
• Mild swelling or soreness of the affected skin
• Larger, firmer, flesh-coloured bumps in deeper forms

Where it appears

In adults: neck, upper chest, back, under the breasts, groin, elbow creases and areas under tight clothing. In babies: neck, shoulders, chest, armpits, diaper area and skin folds.

How long it lasts

Mild heat rash often settles within a few days once the skin is kept cool and dry.

See a doctor if

• The rash lasts more than a week or keeps coming back
• There is increasing pain, swelling, warmth, pus or crusting, which may mean infection
• There is fever or swollen glands
• A baby is unwell, feeding poorly or has a rash that does not look like heat rash
• The rash is widespread or spreads quickly

Call 112 or 102 for heat illness

Confusion, a very high temperature, fainting, a rapid pulse, hot dry skin or seizures can signal heat stroke. Move the person to a cool place and seek emergency help.

Key point

Most heat rash is mild and clears by itself. Infection and heat illness need medical attention.

Before your appointment

Note when the rash began, where it is and what makes it better or worse, such as heat, clothes, creams or sweating. List any products, medicines, oils or herbal pastes you have used, and whether anyone at home has a similar rash. For a baby, note fever, feeding, and what the baby wears and sleeps in. Take photos of the rash over a few days.