How to stop heat rash

What does heat rash look like?

Heat rash causes small, raised spots, an itchy or prickly feeling and sometimes mild swelling. The rash 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. Adults and children often have similar symptoms. The rash can appear anywhere and spread across the body, but it cannot pass to another person.23

Heat rash is also called prickly heat or miliaria, because apparently even a sweat rash needs a formal name. Sweat normally travels through tiny tubes called sweat ducts to reach the skin's surface. When those ducts become blocked, trapped sweat irritates the skin. Hot, humid weather, intense activity and clothing that traps sweat make this more likely. The rash often develops beneath clothing or in skin folds rather than on areas with good airflow.14

What should you do right now?

1. 1Move out of the heat into a cooler room, ideally with air conditioning or a fan. Pause exercise or other activity that makes you sweat.
2. 2Remove extra layers and clothing covering the rash. Change out of wet clothing.
3. 3Gently wash the area with cool or lukewarm water, or take a cool bath or shower. Do not scrub. Pat the skin dry.
4. 4Leave the affected area uncovered where practical, or wear clean, loose clothing that does not rub. Cotton is a useful choice.
5. 5For prickling or itching, apply a cool damp cloth or an ice pack wrapped in a tea towel for up to 20 minutes.

Cooling and airing out the area do the useful work here, without requiring a bathroom shelf audition. Keep the skin cool and dry throughout the day, not just during the first wash. Use light bedding at night, and drink plenty of fluid to avoid dehydration.12

What helps the itching?

Tap or pat the rash instead of scratching it, and avoid perfumed shower gels or creams. Start with cooling rather than adding products. If itching is still troublesome, a pharmacist can help choose a suitable treatment, such as calamine lotion, antihistamine tablets or hydrocortisone cream. Children under 10 need advice from a doctor before using hydrocortisone.23

Calamine can relieve discomfort, but it is drying. If it leaves the skin dry, ask about an appropriate moisturiser rather than adding a thick layer yourself. Cooling remains the main treatment; mild topical steroids are an option for cases needing medical care, not a necessary step for every rash.4

Can creams or powders make heat rash worse?

Heavy lotions, creams, ointments and powders can block pores and keep sweat from escaping, making heat rash worse. Skip products that coat the affected area while it heals. A treatment chosen for intense itching is different from routinely covering the rash with skincare. Scratching can also break the skin and allow an infection to develop, so use cooling or gentle patting for relief.1

How do you treat heat rash in babies and children?

Move your child into a cooler area and remove extra clothing. Use a cool damp washcloth to remove sweat and body oils, or give them a lukewarm bath, then dry excess moisture. Heat rash commonly appears on an infant's neck, armpits, elbow creases and groin; older children can also get it on their chest and back. A child with uncomplicated heat rash should act normally and should not have a fever or other signs of illness.5

For babies, choose lightweight, soft cotton clothing and keep the skin cool and dry. If there is no air conditioning, place a fan far enough away that only a gentle breeze reaches your baby. Avoid baby powders: they do not improve or prevent heat rash. Creams and ointments can keep the skin warmer and block pores. Babies are particularly prone to heat rash because their sweat ducts are still developing and they cannot regulate temperature as well as adults.16

How long does heat rash take to clear?

Most cases resolve within a day or two after moving to a cooler environment, although clearing can take a few days. Many cases need no medication. Continued heat, humidity or sweating keeps the trigger in place, so reducing those exposures matters more than repeatedly applying a soothing product. Arrange a medical review if the rash does not improve after a few days.24

How can you prevent heat rash?

Light clothing and a cool bedroom matter more than an elaborate skincare routine, which is an unusually short shopping list. Reduce time in hot, humid conditions where possible, and take frequent cooling breaks during outdoor work or sport. Change out of wet clothing and avoid tight layers. Breathable cotton or breathable synthetic fabrics allow more airflow than clothing that traps moisture. At night, use a ventilated, cool room and avoid excessive bedding.14

Children can develop heat rash during active outdoor play, when overdressed or when sleeping under too many blankets. For babies, avoid excessive layers while keeping loose cloth or bedding away from their face. Adults who need bedrest, sweat heavily or take medicines that increase sweat gland activity also have a higher risk. Repeated episodes deserve a medical review, especially in children.15

When should you get medical help?

Get medical advice if the rash is worsening, painful, intensely itchy or not improving after a few days. Fever, chills, increasing swelling or warmth around the rash can signal infection. For a child, seek care if they seem ill, have other symptoms or develop blisters, scabs or swollen glands. Contact a doctor if your baby has a rash and you are worried, rather than assuming it is heat rash.125

Do not treat feeling unwell in the heat as only a skin problem. Heat exhaustion can cause heavy sweating, rapid breathing and a fast, weak pulse, and can progress to heat stroke. Confusion, dizziness, nausea, dry skin or a rapid, strong pulse can be signs of heat stroke: get medical help immediately. Hot, humid conditions can overwhelm the body's cooling even when you are sweating.7