What to Know About Heat Rash in Babies

Heat rash happens when sweat ducts in the skin are blocked and sweat gets trapped, creating fluid-filled bumps on the skin.

In most cases, the bumps show up where there’s friction, like where one body part rubs against another, or where tight-fitting clothes rub against the skin.

Did your baby wake up with a rash?

Heat rash can sometimes occur while children are sleeping. If pajamas are bulky, blankets are too heavy, or the fabric doesn’t breathe, these items could be trapping heat and perspiration.

Try these tips:

• Use a light blanket.
• Layer blankets.
• Opt for breathable cotton sleepwear.

If temperatures drop and your baby’s room becomes too cool for comfortable sleeping, it’s better to layer light blankets so you can remove one when the room warms back up.

There are multiple types of heat rash.

Miliaria crystallina

Miliaria crystallina is the mildest type of heat rash. It affects the top layer of skin, which is called the epidermis.

You might see small, clear, blister-like bumps on the surface of your baby’s skin. The bumps aren’t painful. They don’t usually itch, but the lesions can sometimes break open if they’re scratched.

If your baby has a rash, consider putting mittens on their hands to prevent scratching and open wounds.

Miliaria rubra

This red, bumpy rash affects the mid-epidermis, a deeper layer of the outer skin. Miliaria rubra is often called prickly heat because the bumps on the skin can be tender. They can sting or itch, too.

Miliaria rubra is the most common type of heat rash. The rash can cause discomfort and pain. Babies may be irritable while it’s healing.

Sometimes miliaria rubra can develop pustules. This form of the condition is called miliaria pustulosa.

Miliaria profunda

Miliaria profunda affects the deepest layer of skin (the dermis). It’s very rare among babies and toddlers. It occurs when sweat leaks out of the glands, forming fluid-filled pockets under the skin.

The bumps are skin-colored, not clear or red. They’re usually much bigger and tougher than the bumps from other types of heat rash. Although it may look milder, the effects can be more serious.

Symptoms of heat rash include:

• small bumps that may be clear, red, or skin-colored
• redness
• itchiness or a stinging feeling, in some cases

The most commonly affected zones on children’s bodies are:

• neck folds
• elbow and knee creases
• armpits
• inner thighs

Most of the time, heat rash starts clearing up on its own as soon as you cool off your baby. There are several at-home treatments to start healing the rash:

Cool the skin

You can cool the skin by removing extra layers of clothing or by moving to a cooled indoor space. If your baby’s been outside in heat and humidity, remove damp clothing and turn on a fan to dry their skin.

Apply water

• For small rash patches. If the affected area is relatively small — just a patch on the back of the neck or in the creases of the elbows — gently dab a cool, wet cloth on the rash to relieve tenderness and bring down the skin temperature.
• For larger rash areas. You can also give your baby a cool bath for at least 10 minutes, but don’t use soap — it could further irritate the skin. Afterward, let their skin air dry. Supervise your baby at all times during the bath.

Try a steroid cream

It’s important to keep kids from scratching if the rash is itchy. Broken blisters can lead to skin infection.

If it seems that the rash is bothersome to your baby, you can smooth some over-the-counter (OTC) 1 percent hydrocortisone cream onto the bumpy area.

Since steroids can have side effects, discuss their use with your child’s doctor beforehand.

Avoid hydrocortisone ointments that contain petroleum or mineral oil. They can block pores and keep sweat from naturally evaporating.

Use calamine lotion or anhydrous lanolin

If your child has a more severe type of heat rash, calamine lotion can help stop any itching.

Anhydrous lanolin — the kind found in nipple treatments for people who breastfeed — can help keep sweat ducts clear and open.

When to take your baby to a doctor

Heat rash usually clears up on its own within 1 week. If your baby’s skin hasn’t cleared up by then, or if the rash gets worse or looks infected, it may be time to talk with a pediatrician.

As with any rash, if your child develops a fever when the rash appears, it’s also a good idea to check with a doctor. They could prescribe a different steroid cream or advise you on using antihistamines to treat the problem.

Babies are at an increased risk of heat rash due to their higher body temperatures and undeveloped sweat ducts.

Other risk factors for heat rash, in babies or in older children and adults, include:

• sweating
• living in a hot, humid, or tropical climate
• having a fever
• wearing clothing that sticks to the skin

There are multiple steps you can take to help your baby avoid heat rash.

Pause

When you’re at the park or on the playground, check to be sure your child isn’t getting overheated during playtime.

If you notice damp clothing or flushed skin, remove a layer of clothing or move to a shady or air-conditioned space for a while.

Keep them hydrated

Whether you’re playing in cold or warm temperatures, make sure to take frequent breaks for milk or water. When your baby’s hydrated, body temperatures are more likely to stay at healthy levels.

Dress them in layers

If you’re headed out to play in cold weather, dress your baby in clothing made of breathable, moisture-wicking fabric that allows sweat to evaporate from the surface of the skin.

Be cautious about adding too many layers. When kids romp vigorously, layers can trap body heat and sweat. The best practice is to dress your child about as warmly as you’d be in the same temperatures.

Look for proper sleepwear

The Consumer Product Safety Commission recommends that a child’s pajamas (from 9 months to size 14) fit close to the skin and not too loosely.

The American Academy of Pediatrics recommends the use of flame-retardant sleepwear and clothing due to the risk of serious injury from burns.

Keep these recommendations in mind when purchasing sleepwear.

For example, cotton is one natural fiber that allows your child’s body to release heat and sweat. Some cotton items may be pretreated with a special chemical that also makes them flame retardant.

Re-rinse laundry

Detergent or residue from laundering may stay in fabrics and cause skin irritation or contribute to heat rashes. Adjusting your laundry routine a little might help reduce how often heat rashes happen.

Try adding an additional rinse cycle or adjusting your detergent levels. Learn more about laundry detergent rashes.

Heat rash is a skin condition that comes from blocked sweat ducts. The bumps could be clear, red, or skin-colored, depending on how severe the rash is. The bumps might be sore or itchy.

Most of the time, the rash will go away on its own as soon as you cool off your baby’s skin. You can also treat it with cool water, hydrocortisone cream, or calamine lotion.

If the rash doesn’t clear up in a few days, talk with a doctor to be sure your baby’s skin hasn’t become infected. The doctor may prescribe other creams or antihistamines to help with recovery.