How to manage heat rash

What does heat rash look and feel like?

Heat rash, also called prickly heat or miliaria, causes small, raised bumps that feel itchy or prickly. The rash develops when sweat glands become blocked and sweat gets trapped beneath the skin. Hot, humid weather and excessive sweating are common triggers. Anyone can develop heat rash, but babies and young children get it more often.1234

What should I do first?

1. 1Move somewhere cool and ventilated. Limit time in the heat and take a break from activity that keeps you sweating. A cooler room is part of the treatment, even though it does not come in skincare packaging.
2. 2Take a cool or lukewarm shower or bath. This can wash away sweat and help ease itching. Avoid long baths or showers.
3. 3Keep the affected skin cool and dry. For an itchy patch, hold a cool, damp towel against it.
4. 4Change into loose cotton clothing. Avoid tight clothes and fabrics that trap heat and moisture. Loose clothing belongs in the plan, which gives the wardrobe a rare job in skincare.
5. 5Pat or tap itchy skin instead of scratching. Keep nails clean, short and smooth to help avoid skin damage.

Should I use moisturiser or an itch cream?

For heat rash specifically, avoid emollients, meaning moisturisers. Moisturising can help other causes of itchy skin, such as dryness, but it is not the default treatment for a rash caused by trapped sweat. Keep cooling and drying the skin at the centre of the plan rather than adding your usual moisturiser to the affected area.15

Hydrocortisone is a corticosteroid medicine that reduces inflammation, meaning swelling, and can relieve itching. Skin creams, ointments and lotions containing hydrocortisone can be used for heat rash. Ask a pharmacist which preparation is appropriate and how to use it; the form of hydrocortisone matters, because the medicine also comes in tablets and injections for other conditions.26

Tell the pharmacist where the rash is and whether you have other symptoms. Antihistamines help some causes of itching, so do not assume an antihistamine tablet is the right choice just because the rash itches. A pharmacist can help choose a cream or lotion and tell you whether the rash needs a doctor's assessment.5

While the skin is itchy, avoid perfumed soaps, deodorants and moisturisers. Choose laundry liquid or powder intended for sensitive skin. These are general measures for reducing irritation, rather than a replacement for getting out of the heat.5

How long should I wait for it to improve?

See a doctor if the rash has not improved after a few days in a cool place. Seek help sooner if it covers a large area, keeps coming back or worries you. Severe itching, itching that interrupts daily life or itching all over the body also deserves assessment. Do not keep treating a persistent rash as heat rash without having the cause checked.25

Which changes need medical attention?

• Contact a doctor for warmth, pus, yellow or green fluid, or red streaks around the rash. Heat rash spots can become infected.
• Get the rash checked if there is fever, severe pain or constant itching.
• Seek assessment for blisters, especially around the eyes, mouth or genitals.
• Call emergency services for a sudden rash that spreads quickly, trouble breathing or facial swelling. These can be signs of a severe allergic reaction rather than heat rash.

When is it more than a skin problem?

Do not treat dizziness, headache, nausea or vomiting during heat exposure as just part of the rash. These can indicate heat exhaustion, which needs immediate medical attention. Heavy sweating, rapid breathing and a fast, weak pulse are further warning signs. Get out of the heat while arranging help.17

Confusion, unusual behaviour, slurred speech or loss of consciousness in the heat can indicate heat stroke. Call emergency services immediately and move the person out of the heat while helping them cool down. Heat stroke is life threatening; do not wait for a rash cream to work.12

What about babies, children and pregnancy?

A child's itchy, prickly rash of small raised spots can usually be managed at home if it is heat rash. Get urgent medical advice if a baby under 3 months has a temperature of 38 degrees Celsius or higher, or a child aged 3 months or older has a temperature of 39 degrees Celsius or higher. A child can still be seriously unwell without a fever.3

Call emergency services if a child with a rash has difficulty breathing, a stiff neck, confusion, unusual responsiveness or a rash resembling bruises that does not fade when pressed with a glass. Do not assume these symptoms are caused by overheating.3

If you are pregnant and develop itchy skin, contact your doctor or midwife rather than assuming it is heat rash. Itching during pregnancy can sometimes be caused by a liver condition called intrahepatic cholestasis of pregnancy.5

How can I reduce repeat episodes?

Limit time in hot conditions, use shade or air conditioning, and avoid tight, heavy clothing that traps heat and moisture. Drink fluids to prevent dehydration in hot weather. Working or exercising in high heat raises the risk of heat illness, and certain medicines can also raise that risk.27

If the rash keeps returning, tell your doctor about new soaps, lotions, cosmetics and household products, as well as substances you touch at work. A summer rash can also come from irritation or an allergic reaction, so the weather alone does not identify the cause. Bring the product history to the appointment; your bathroom shelf may have relevant paperwork.24