Heat rash gives a prickly itchy feeling and a rash that looks like small red raised spots – although more flesh-coloured than red in skin of colour. It can occur anywhere on the body. It's a harmless rash that can improve on its own after a few days.
Heat rash is unsurprisingly caused by excess heat. In situations where the temperature is raised, excessive sweating causes the sweat glands to trap sweat and become blocked, which then leads to a rash reaction. It cannot be passed from one person to another. Babies, especially newborns, are not good at controlling their temperature, so they can get heat rash more often.
The best thing to do is to keep your skin cool. This can be done by avoiding too many clothing layers and ensuring the surrounding environment is cool. Loose cotton clothing and lightweight bedding is advised, as well as drinking plenty of water to avoid dehydration, and taking cool baths or showers. If you experience itching you should keep your nails short, pat the skin instead of itching and try running an ice pack wrapped in cloth, or something else cool along the skin for 10 to 20 minutes at a time.
A pharmacist might recommend creams or lotions with anti-itching components like calamine lotion. They may recommend antihistamine liquid or tablets to reduce the sensation to itch. If the rashes are red and inflamed a small amount of hydrocortisone cream for children over 10 years old and non-pregnant adults can be trialled. When compared to modern antihistamines such as loratadine or cetirizine, older antihistamines such as chlorphenamine (the active component of Piriton) are particularly helpful for skin reactions or rashes. They improve symptoms often within a few hours. Some people find it a disadvantage they can cause drowsiness, although if the rash is bothersome at night, this may be desirable. They also require more frequent doses throughout the day. Cetirizine is an effective all-around antihistamine with wide symptom coverage and a once-daily dose that is less prone to causing drowsiness.
If the rash is not improving with those home methods after a few days or you or your child are having more worrying symptoms, you should contact your doctor for further review. Your doctor can offer diagnosis if you are unsure that your rash is a heat rash.