What is the medical term for sweat rash?

What do the different miliaria names mean?

Heat rash often looks red on white skin, but can look grey or white and be harder to see on brown or black skin. Some spots contain fluid. The symptoms are often similar in adults and children, and heat rash cannot be passed to another person.3

Why does sweat rash happen?

Sweat normally travels through tiny tubes called sweat ducts to reach the skin's surface. Blockage or inflammation of those ducts causes miliaria. Hot, humid weather, intense exercise, fever and clothing that traps moisture can contribute. Heat rash affects all ages, but newborns are particularly susceptible because their sweat ducts are immature. Being bedridden, especially against a waterproof mattress cover, also increases the risk. Warm weather is not essential: overdressing can cause miliaria even in cool weather.12

How do you treat sweat rash?

Cooling and drying the affected skin come first, rather than expanding your skincare routine, which gives the bathroom shelf a rare opportunity to do less.2

1. 1Move to a cooler area, ideally somewhere with air conditioning.
2. 2Remove clothing covering the rash. Gently wash the skin with cool or lukewarm water, then pat it dry without scrubbing.
3. 3Leave the area uncovered where practical, or wear clean, loose clothing that does not rub.
4. 4Apply a cool, damp cloth when the skin feels prickly. A cold compress can be used for up to 20 minutes.
5. 5While the rash heals, limit activities that cause heavy sweating and avoid scratching. Tap or pat the area instead.

Avoid thick ointments and clothing that seals in sweat. Skip perfumed shower gels and creams. If itching needs treatment, a pharmacist can advise about calamine lotion, antihistamine tablets or hydrocortisone cream. Children under 10 need a doctor's advice before using hydrocortisone. Calamine can soothe discomfort but can also dry the skin, so ask about suitable care if dryness develops.123

Most cases settle within a day or two after moving to a cooler environment, although clearing can take a few days. To reduce repeat episodes, keep the bedroom cool and ventilated, remove wet clothing and avoid excessive or tight clothing.1

Is every rash after sweating miliaria?

No. Cholinergic urticaria is a different condition that causes small, itchy hives after triggers such as heat, exercise or emotional stress. Those hives typically last 15 to 30 minutes and can occur without sweating. Miliaria involves obstructed sweat ducts. A clinician usually identifies miliaria from the rash's appearance and the circumstances in which it developed.25

When should you get medical help?

See a healthcare professional if the rash does not improve after a few days, becomes painful or intensely itchy, or develops swelling, warmth, pus, fever or chills. Seek advice if you are worried about a baby's rash or suspect another cause. Heat rash is a mild heat illness, but dizziness, nausea, vomiting or headache after heat exposure can signal heat exhaustion and need immediate medical attention. Confusion, behaviour changes or slurred speech can signal heat stroke, a medical emergency.46