Seeing Red? How to Treat and Prevent Baby Heat Rash

Is your little one's skin looking red and bumpy? It may be heat bumps on baby. Learn how to treat heat rash—and prevent it from cropping up in the first place.
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profile picture of Liz Kreiger
Contributing Writer
May 27, 2021
Illustration of beach scene with umbrella and beach accessories like flip flops scattered on the sand.
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There you are, enjoying a warm, sunny day at the beach with your family when you suddenly notice that baby’s neck has a red rash all over it. In fact, the rash seems to be spreading as time passes and the heat of the afternoon peaks. What is this rash? And should you be worried?

Don’t fret—baby is probably experiencing what’s known as heat rash. While it can be pretty uncomfortable for baby, and alarming for you to see, the good news is that it’s easy to treat and usually not cause for concern.

Because it’s not uncommon for babies to develop rashes here and there, it’s important to be able to identify specific types of rashes, know how to address them and determine whether there’s a medical issue at hand.

To help you get more acquainted with newborn heat rash, we’re sharing all the information you need to know if you happen to spot these raised and red heat bumps on baby. Read on to learn what heat rash on baby looks like, how to get rid of it and ways to prevent it in the first place.

What Causes Heat Rash in Babies?

The cause of heat rash is right there in its name: heat. Simply put, baby is a bit overheated, and their tender skin is sending out a warning signal. Remember, baby’s skin is especially thin and sensitive, and outside factors can do a number on it.

While heat rash most commonly strikes during the warmer months of the year and in more humid, tropical climates (aka your summer beach vacation), it doesn’t only pop up in the summer—heat rash can rear its head when baby is just too bundled up for a trip to the mall.

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Heat rash occurs in small children and adults alike, but babies under one are more frequently affected. This is because the rash is primarily caused by blocked sweat glands—and infants’ sweat glands are smaller and still developing, leading to trapped perspiration under the skin, says Jennifer Trachtenberg, MD, a pediatrician and assistant clinical professor at the Icahn School of Medicine at Mount Sinai, in New York City.

Heat bumps on baby typically crop up in spots where moisture can get trapped: the armpits, diaper area and skin folds of the neck and upper chest.

How to Tell If It’s Heat Rash

Generally, newborn heat rash is easy to identify. Most of the time, it looks like lots of little red bumps, says Lauren Geller, MD, director of pediatric dermatology at Mount Sinai Hospital. In some cases, it can resemble clusters of pimples or blisters. It can be itchy or create a prickly feeling and show up as blotches on various parts of the body.

While it might be hard to distinguish heat rash from eczema, the latter tends to be much itchier, Geller says. Still, because the rash can be bothersome, you may notice that baby seems fussy, cranky or out of sorts. They may be antsy and have trouble falling or staying asleep.

There are three types of heat rash, although the differences just stem from how deep the affected sweat glands are in the skin.

Miliaria crystallina. This type of rash means the glands close to the skin’s surface are involved and leads to bumps that are almost clear in color instead of the usual red, Geller says.

Miliaria rubra. Miliaria rubra occurs a bit deeper in the skin, and the bumps are typically red and often itchy. (This type has the nickname “prickly heat” because of that sensation.)

Miliaria profunda. The most severe (and rare) form of heat rash, miliaria profunda involves sweat glands even deeper down and can cause firm, flesh-colored lesions that look like goosebumps.

It’s worth noting that many illnesses that can cause a skin rash are viral in nature (including the mosquito-borne Zika virus). These are usually accompanied by additional symptoms, such as a fever, headache or listlessness, Trachtenberg says, but heat rash (thankfully!) is not.

How to Treat Baby’s Heat Rash

To get rid of newborn heat rash, you’ll first need to cool baby down, Trachtenberg says. This means removing baby from the situation that’s causing them to overheat to begin with. Take your infant out of the sun and head indoors to find relief in an air-conditioned room.

Next, remove excessive clothing layers. Choosing light, loose-fitting cotton clothing helps baby stay dry and cool and is a good way to avoid heat rash altogether. This holds true even in winter: Too many tight layers can cause baby to overheat at any time of year. You can also let baby go without clothes for a bit to prevent chafing and further irritation.

Once baby is more suitably dressed (or undressed!), place a cold compress on warm areas and pat the skin dry with a towel so moisture doesn’t get trapped.

If baby has been scratching at the rash, quell the itch and soothe the skin by applying a bit of topical calamine lotion. Just don’t overdo it, Trachtenberg says, “because too many creams or lotions can further block the ducts.” It’s also best to avoid any additional products at this time—less is more when it comes to getting baby’s skin back to normal. When in doubt, contact your doctor for advice on using topical creams.

At bedtime, keep baby from sweating while they sleep by maintaining a cool environment, whether it’s via an open window, fan or air-conditioner. The ideal sleeping temperature for baby is around 70 degrees Fahrenheit.

How long does baby heat rash last?

The great thing about heat rash? It doesn’t last that long. Most of the time, heat rash goes away within a few days, if not much, much sooner. The faster you cool off your child, the faster the rash will dissipate. Eliminate the cause for overheating, and baby should start healing right away—it’s that simple.

When to Contact the Doctor About Baby’s Heat Rash

You should contact your doctor if baby’s heat rash doesn’t get better—or if it gets worse—after a few days, Trachtenberg says. You’ll also want to seek help if the rash continues to spread, the bumps start to drain pus or if baby develops chills or a fever.

While it’s true that babies get their fair share of rashes, don’t hesitate to reach out to your doctor if you have questions or concerns. When it comes to baby’s health, it’s always best to err on the side of caution.

In the meantime, keep an eye on the temperature outside and be mindful of what baby is wearing to help prevent pesky heat bumps on baby.

Newborn heat rash happens, but knowing what to look for and how to treat it can empower you to enjoy your fun in the sun without worry—you definitely know how to keep your cool.

About the experts:

Jennifer Trachtenberg, MD, is a pediatrician and assistant clinical professor at the Icahn School of Medicine at Mount Sinai, in New York City, where she also earned her medical degree.

Lauren Geller, MD, is the director of pediatric dermatology at Mount Sinai Hospital in New York City, as well as an assistant clinical professor in pediatrics and dermatology. She earned her medical degree from the Brown Medical School.

Please note: The Bump and the materials and information it contains are not intended to, and do not constitute, medical or other health advice or diagnosis and should not be used as such. You should always consult with a qualified physician or health professional about your specific circumstances.

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