useful links


Heat Rash

By Dr Evelyn Lewin

A heat rash, as the name implies, is a rash that can develop following exposure to heat. This can happen on a hot day, when exercising in the heat, or even when dressed too warmly. Heat rash occurs when sweat glands are blocked. This means sweat cannot escape the body (which is how the body usually cools itself). The rash develops because of the trapped sweat. If large areas of skin are affected, heat rash can lead to heat stroke.


The rash causes itchy red bumps, or blisters, on the skin. Because sweat is blocked, the skin is dry to touch. The rash is more likely to occur in skin folds (such as under the arms). The rash usually goes away once skin has cooled down. However, the sweat glands may become infected and form a painful, pimple-like rash. Heat rash can also happen as part of other heat-related conditions, including heat stroke. Heat stroke occurs when the body temperature rises above 40.5C. It is a medical emergency.


If your child has heat rash, drink water and cool her down. This can be done by taking her to an air-conditioned room and dressing her in light, breathable clothes. Don’t use creams or lotions while heat rash is present as it can further clog the skin. Keep the affected skin cool and dry. If you are concerned, see your doctor. Once the heat rash is gone, calamine lotion can help if the prickly feeling persists. Practice these tips to prevent heat rash:
– On hot days play inside with the air-conditioning on
– Maintain good hygiene, keeping skin clean and dry
– Minimise the time your child spends being active outdoors on hot days
– Don’t overdress children (even in colder months)
– On hot days, dress children in loose-fitting, breathable materials such as cotton

If you think your child has infected sweat glands, see your doctor. If you are concerned your child is suffering heat stress or heat stroke, seek urgent medical assistance.

Reviewed by Dr Evelyn Lewin 25 February 2015 references
  • current version

    Evelyn Lewin

    Evelyn Lewin
  • document id

  • next review


This document has been developed and peer reviewed by a KIDS HEALTH Advisory Board Representative and is based on expert opinion and the available published literature at the time of review. Information contained in this document is not intended to replace medical advice and any questions regarding a medical diagnosis or treatment should be directed to a medical practitioner.

LEAVE A COMMENT 0 comments