What causes sweat rash?
Heat rash develops when sweat ducts become blocked or inflamed. Hot, humid weather, intense exercise, fever and clothing that traps heat can contribute. It can affect any age group. In adults, common sites include the upper body, scalp, neck and skin folds, especially where clothing rubs.1
What does sweat rash look and feel like?
Typical symptoms are small, raised spots, an itchy or prickly feeling and mild swelling. Spots are around 2 to 4 mm across, and some contain fluid. The rash looks red on white skin but can look grey or white, or be harder to see, on brown or black skin. Heat rash can spread across the body, but cannot pass to another person.2
How to treat sweat rash at home
- 1Move somewhere cooler and remove wet or tight clothing.
- 2Change into loose cotton clothing and use lightweight bedding.
- 3Take a cool bath or shower.
- 4For itching, apply a cold damp cloth or an ice pack wrapped in a tea towel for up to 20 minutes.
- 5Tap or pat the rash rather than scratching, and avoid perfumed shower gels or creams.
Lightweight bedding helps keep skin cool, which gives the bedding a job beyond looking respectable.2
Can a pharmacist help?
A pharmacist can suggest calamine lotion, antihistamine tablets or hydrocortisone cream. Children under 10 need advice from a doctor before using hydrocortisone for heat rash. Ask the pharmacist which option is suitable and how to use it.2
Calamine can relieve discomfort, but it is drying, so an emollient, a moisturising treatment, is sometimes needed alongside it. Cooling remains the main treatment: reducing heat and humidity reduces the sweating that drives the rash.1
What if a baby or child has sweat rash?
Babies and young children have a higher risk of heat rash than adults. The rash can appear suddenly as small bumps with a change in skin colour, and the skin can feel itchy or prickly. Take the child to a cool place to stop the sweating. Cooling helps the child feel more comfortable and allows the rash to clear on its own over a few days.3
Small bumps alone do not identify heat rash. Children's rashes can look alike, and irritation, eczema and infections can also cause bumps or blisters. A doctor can check the cause if you are unsure. If the rash is still present after a few days, contact your child's doctor.3
How long should sweat rash last?
Most cases resolve within a day or two after moving to a cooler environment, without needing medicine. Other skin problems, including fungal infections and inflammation or infection of hair follicles, can resemble heat rash. A persistent rash needs assessment rather than repeated treatment as presumed prickly heat.1
See a GP if heat rash does not improve after a few days, or if your baby has a rash and you are worried.2
Get medical advice if the rash worsens rather than settling. Do not wait for it to meet a particular number of days before asking for help.4
How can you stop sweat rash coming back?
Reducing heavy sweating helps lower the risk of prickly heat. Wear lightweight, loose cotton clothing in hot weather. If you exercise outdoors, choose the coolest parts of the day; alternatively, move your workout indoors somewhere with air conditioning. Cool showers, fans and air conditioning can help keep skin cool.4
Fans and air conditioning help keep skin cool, so the most useful equipment is not necessarily in the bathroom cabinet.4
At night, sleep in a cool, ventilated bedroom. Avoid excessive clothing, remove wet clothing and avoid excessive soap or other irritants. These measures reduce heat, trapped sweat and irritation rather than just treating the itch after the rash appears.1
