Baby heat rash (prickly heat)

What causes heat rash?

Your baby may get a heat rash when their pores become so clogged that the sweat can't get out. Babies are prone to prickly heat because they have smaller pores than adults. Many situations that lead to overheating can cause a baby or toddler to develop heat rash, including:

• Hot, humid weather
• Being overdressed in too many layers of clothes, even in winter
• A fever
• Intense physical activity

What does baby heat rash look like? 

Prickly heat looks like patches of little bumps, or sometimes tiny blisters on your child's skin. The bumps may appear red, especially on light skin.

You're most likely to see a heat rash on:

• The back of your baby's neck
• Their shoulders and chest
• Areas where clothing fits more snugly, including the diaper area (especially where it rubs against the waistline)
• The scalp or forehead if they're wearing a hat
• Folds in the skin, such as the neck, groin, armpits, elbow creases, and backs of the knees

Types of heat rashes

Kids get lots of rashes, and it can be hard to tell one from the other. A heat rash looks like little bumps with red skin around them. Each specific type of heat rash has its own unique look.

Miliaria crystallina

This type of heat rash happens when the opening of the sweat glands is blocked. It happens because your baby's sweat glands haven't fully developed. You'll see small, clear fluid-filled bumps on your baby's skin that easily break open.

Miliaria rubra

Sometimes called "prickly heat," this is the most common type of heat rash babies can get. Sweat glands are blocked deeper under the skin, which causes inflamed bumps, itching, and a prickly sensation. Symptoms get worse when the child sweats. In newborns, this rash shows up in the groin, under the armpits, and in the neck.

Miliaria profunda

This less-common type of children's heat rash happens deep under the skin. It creates big, hard, flesh-colored bumps that may be very itchy. The bumps usually appear on a baby's trunk, but they can also pop up on the arms and legs when they sweat. Once your baby stops sweating, the rash should clear up.

Symptoms of heat rash in babies and toddlers

Look for baby heat rash symptoms like these:

• Small red or fluid-filled bumps that pop up when your child is very warm
• Red skin around the rash
• An itchy or prickly sensation
• Rash in areas like your baby's neck, chest, armpits, elbow creases, and groin
• No fever or other signs of illness

Are heat rashes serious for babies and children?

No. A baby heat rash isn't serious. It will usually clear up on its own without any problems or scars. But if bacteria get inside the sweat glands, they can cause an infection. Heat rashes aren't contagious, so they can't spread from person to person, but a rash can spread to a wider area of your child's skin.

Heat rashes on their own aren't a problem, but they are a sign that your child is too warm, and overheating can lead to serious conditions such as heat exhaustion and heat stroke. Being too warm during sleep can also raise your baby's risk of sudden infant death syndrome (SIDS).

Heat rash isn't usually painful, although an outbreak can be itchy. Some bumps may be tender to the touch. You may want to trim your child's fingernails so they don't scratch themselves if the rash starts itching. Or use long sleeves with the little flaps that fold over their hands, so your baby won't scratch while they sleep.

How to treat heat rash in babies and toddlers

Start by using cooling techniques to bring down the rash. Bring your child out of the warm environment and into the shade or air conditioning. Apply a cool washcloth over their skin or put them into a cool bath.

After rinsing your child off, let their skin air-dry or pat it dry rather than rubbing with a towel. Put them in loose, lightweight clothing made of a breathable fabric like cotton.

If the itch is intense, ask your baby's pediatrician about using an over-the-counter anti-itch medicine like a corticosteroid or calamine lotion.

Try to avoid using any products like greasy moisturizers that might block the sweat glands even more.

Ways to prevent baby and toddler heat rash

The best way to prevent heat rash is to keep your child from getting overheated.

Dress them lightly. Put your child in loose-fitting, lightweight clothing when it's warm outside. Layer them in the winter, rather than putting on heavy clothes. Natural fabrics, such as cotton, are absorbent and allow kids to sweat more efficiently than most synthetics. Lightweight and breathable bedding helps, too.

Do regular heat checks. Check on your child often, especially in hot weather, to see if they're at a comfortable temperature. If their skin feels damp and hot, they're too warm. Cool them off with a wet washcloth, a dip in the pool, or a lukewarm bath.

Choose a cooler location. On a hot day, keep your child in an air-conditioned space, or look for cool, shady, or breezy places to play outside.

Hydrate. Make sure your baby is well hydrated by breastfeeding or formula-feeding often. Offer your toddler or young child plenty of water to help them stay hydrated. (Don't give water to a baby younger than 6 months unless the doctor recommends it.)

Keep dry. Pay attention to skin areas that tend to get moist, such as the neck, diaper area, and other places where skin folds can trap sweat, urine, or drool, which can make the rash worse. Try to keep these areas clean and as dry as possible.

Don't use baby powder. Not only can it cause breathing problems and irritate your baby's lungs, but it also can block pores and make the skin feel warmer.

Turn on the air. If it's hot at night, use an air conditioner or a fan in your child's room. Direct the fan near your child but not so it's blowing directly on them. Or place it far enough away so that only a gentle breeze reaches them. You want them to be comfortable, not chilled. (Keep cords, which are strangulation hazards, out of your child's reach.)

When to call your provider about your child's heat rash

Most of the time heat rash will clear up on its own, without a visit to your doctor. Definitely see your provider if:

• The rash looks like it's getting worse.
• Your child is running a fever.
• The rash shows signs of infection (it feels warm or is swollen, red, oozing pus, or forming scabs).
• It's very itchy.
• The rash doesn't go away after three or four days.

Skin rashes can sometimes be hard to identify. Here's a visual guide to common children's rashes to help.

Learn more

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