Sweat rash spots: what they look like and how to treat them

What do sweat rash spots look like?

Sweat rash is also called heat rash, prickly heat or miliaria. The common itchy form produces small raised spots, sometimes containing fluid, with mild swelling. Spots often look red on white skin, but can look grey or white and be harder to see on brown or black skin. Heat rash can spread across the body, but it is not contagious.1

Why do the spots appear after sweating?

Sweat ducts are the tiny tubes that carry sweat to the skin surface. When they become blocked, sweat backs up and leaks into the skin, producing bumps or blisters. The depth of the blockage determines the type of rash. Hot, humid weather, intense exercise, fever and tight clothing all make heat rash more likely. Skin covering items, including medication patches, can also contribute.5

Sweating is how the body cools itself, and sweating more during heat, exercise, anxiety or fever is normal. The aim is to reduce overheating, not eliminate normal sweating. Too little sweating can be dangerous because the body can overheat.6

How to treat sweat rash spots

1. 1Move somewhere cooler. Use an air conditioned room or another cool indoor space if possible.
2. 2Remove clothing covering the rash. Replace sweaty clothes with clean, loose clothing that does not rub.
3. 3Gently wash the area with cool or lukewarm water. Pat the skin dry rather than scrubbing.
4. 4Leave the area uncovered where practical. Otherwise, choose loose, airy clothing.
5. 5Apply a cool washcloth when the prickly feeling bothers you.
6. 6Pause exercise and other activities that cause heavy sweating until the rash has gone.

For itching, hold a cool damp cloth against the skin, or use an ice pack wrapped in a tea towel, for up to 20 minutes. Tap or pat the rash instead of scratching it. Avoid perfumed shower gels and creams. Lightweight bedding and cool baths or showers help prevent another round of overheating.1

Loose clothing gives skin more airflow, which is a modest job description for something sold as a summer wardrobe.2

Should you put cream on sweat rash?

Cooling and airing the skin come first. Creams, ointments and powders that block pores can keep sweat trapped and worsen the rash, so do not coat the area with products simply because they sound soothing. Ask a pharmacist or clinician before adding a topical treatment. A product shelf cannot supply ventilation, however convincingly the bottles are arranged.2

Calamine lotion can relieve discomfort, but it is drying. If dryness becomes a problem, ask about a suitable moisturiser rather than layering on a heavy ointment. More severe rashes sometimes need a mild steroid cream, while secondary bacterial infection can require antiseptics or antibiotics.3

A pharmacist can suggest calamine, antihistamine tablets or hydrocortisone cream depending on the symptoms. Children under 10 need advice from a doctor before using hydrocortisone for heat rash. There is no single application schedule for all these treatments; follow the directions for the specific medicine you are advised to use.1

How long should sweat rash last?

Most cases settle within a day or two after moving to a cooler environment, although clearing can take a few days. If the rash is not improving after a few days of cooling, arrange a medical assessment rather than continuing to treat it as heat rash.34

What if a baby has sweat rash spots?

Babies are more prone to heat rash because their sweat glands are not fully developed. Spots can appear on the face, neck, upper chest, skin folds and nappy area. Move your baby to a cooler room or shaded area, remove extra layers, and change sweaty clothes and wet nappies regularly. Choose loose, light cotton clothing and keep the skin clean and dry.4

Do not put loose cloths or bedding near a baby's face while trying to cool them. Contact your child's clinician if the rash lasts longer than a few days or keeps recurring. If you are worried about a baby's rash, seek advice even if you think it is heat rash.12

Could spots after sweating be something else?

Brief episodes of tiny, itchy raised welts after exercise, heat or emotional stress can be cholinergic urticaria, a type of hives. These welts typically last 15 to 30 minutes and can occur without sweating. That short lived pattern differs from a heat rash that remains for days.7

Acne, fungal infections and folliculitis, inflammation around hair follicles, can also resemble heat rash. Heat rash bumps are typically not centred on hairs. A clinician usually diagnoses heat rash by examining the spots; severe or repeated episodes sometimes need a small skin sample to clarify the cause.3

When should you get medical help?

• Arrange an assessment if the rash covers a large area, looks unusual, keeps returning or fails to improve after a few days somewhere cooler.
• See a clinician for pain or intense itching.
• Seek urgent care for pus filled lumps, redness around the rash or fever. Warm, swollen skin and chills also need assessment for infection.
• Seek emergency care if you or your baby has signs of heatstroke.

For an appointment, note when the spots started, where they appeared, recent heat exposure, exercise or illness, and any new skincare products. Mention your medicines and previous episodes. Some medicines increase sweating, and these details help distinguish heat rash from other causes.5

How to stop sweat rash returning

Keep indoor spaces cool with ventilation, a fan or air conditioning. Avoid heat and humidity where practical, wear loose cotton clothes, and avoid fabrics that irritate or trap heat and sweat. Take cooling breaks during outdoor activity. Prevention is mostly a matter of temperature and clothing, which leaves remarkably little work for a luxury bottle.24