What to Do About Your Baby's Heat Rash
Heat rash, also called prickly heat or miliaria, shows up as patches of small pink or red bumps where a baby sweats and the sweat cannot escape. It is common in babies because their sweat ducts are still developing, and it appears most in hot, humid weather or under too many layers. The good news is that it usually clears on its own once the skin cools. This guide covers what causes it, how to prevent it, how to treat it, and when it needs a doctor.
What heat rash is
Heat rash develops when the openings of the sweat glands become blocked and sweat is trapped under the skin instead of evaporating. The result is clusters of tiny pink or red bumps or small blisters. It is most common in early infancy and in hot, humid conditions.
It tends to appear in skin folds and covered areas: the neck, the armpits, the elbows, the thighs, the upper chest and back, around the hairline, and under the diaper. Tight clothing, extra layers, blankets, or being buckled into a seat where air cannot circulate all make it more likely.
How to prevent it
Preventing heat rash mostly means keeping your baby cool and letting their skin breathe.
- Dress your baby in loose-fitting cotton clothes when it is warm.
- Avoid extra layers and overdressing, indoors and out.
- Use fans or air conditioning to keep the room from getting hot and humid.
- Take babies out of carriers and car seats during long warm stretches so air can reach the skin.
How to treat it
Heat rash heals once the skin cools down and the heat that caused it is removed. Cool your baby with a lukewarm bath or a moist compress, then dry the skin thoroughly. Leave the affected areas open to the air when you can, and dress your baby in thin, loose cotton.
Do not apply thick, greasy ointments or heavy creams to the rash. They can block the sweat glands further and make the rash last longer. Keeping the skin cool, clean, and dry is the most effective treatment.
When to call the doctor
Most heat rash clears within a few days of cooling and drying the skin. Contact your pediatrician if the rash is not gone after about 3 days of home care, or if it is getting worse over the course of a day.
Also call if you see signs of infection, such as areas that are tender or draining pus, or if your baby develops a fever or is eating or acting differently. These can mean the skin needs medical treatment rather than just cooling.
Common questions
- What causes heat rash in babies?
- Heat rash happens when a baby's sweat gland openings become blocked and sweat is trapped under the skin. It is common in hot, humid weather and under tight clothing or extra layers, and it appears as small pink or red bumps.
- Where does heat rash usually appear on a baby?
- Heat rash shows up in skin folds and covered areas: the neck, armpits, elbows, thighs, upper chest and back, around the hairline, and under the diaper, where sweat cannot easily escape.
- How do I treat my baby's heat rash at home?
- Cool the skin with a lukewarm bath or moist compress, dry it thoroughly, and leave the area open to the air. Dress your baby in loose cotton. Avoid thick or greasy creams, which can block sweat glands and prolong the rash.
- Should I put cream or ointment on heat rash?
- Avoid thick, greasy ointments and heavy creams on heat rash, because they can further block the sweat glands. Cooling the skin, keeping it dry, and dressing your baby in loose cotton work better.
- How long does baby heat rash last?
- Heat rash usually clears within a few days once the skin is kept cool and dry. If it is not gone after about 3 days of home care, or it is getting worse, contact your pediatrician.
- When should I call a doctor about heat rash?
- Call your pediatrician if the rash lasts more than about 3 days, worsens over a day, or shows signs of infection such as tenderness or pus, or if your baby develops a fever or seems unwell.
- How can I prevent heat rash in hot weather?
- Dress your baby in loose cotton, avoid extra layers, and keep rooms cool with fans or air conditioning. Take babies out of carriers and car seats during long warm stretches so air can reach their skin.
Sources & further reading
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App Store Google Play Open Web AppThis guide reflects current AAP, CDC, and other public-health guidance and is for educational purposes only. It does not constitute medical advice. ParentFlow is a wellness companion — not a substitute for your pediatrician. For any medical concern, contact your healthcare provider.