Heat rash is a skin condition that often develops in hot and humid environments. Although it can be annoying, it typically doesn’t last too long.

Eczema, on the other hand, is a long-term, chronic condition that needs ongoing treatment and symptom management.

Although the two conditions may have some similarities in their appearance, they’re not the same.

Read on to learn more about how to tell the difference between these two skin conditions, how to treat them, and when to get medical attention.

You can blame your sweat glands and perhaps your summer wardrobe for heat rash, which typically happens in warm, humid conditions.

To cool your body down when you’re warm, sweat is produced by glands in the deeper layers of your skin. But if the pores in your skin get clogged, the sweat can’t be released onto the surface of your skin. In some cases, clothing that doesn’t allow your skin to breathe may also play a role in trapping the sweat.

When sweat gets trapped by clogged pores or clothing, it can cause a heat rash to develop. The good news is that heat rash is usually not serious, and it generally doesn’t last too long.

There are three kinds of heat rash:

  • Miliaria crystallina. This is the mildest form and tends to show up as a wave of white or clear fluid-filled bubbles or blisters on the skin. This type of heat rash often appears on the shoulders, neck and chest. It’s more common in babies than adults.
  • Miliaria rubra. Your grandmother probably referred to this as “prickly heat.” It develops when sweat gets trapped under your skin. This rash is uncomfortable and itchy, with red bumps that tend to appear on your shoulders, neck, or chest, or where your clothes rub against your skin.
  • Miliaria profunda. This is the most severe type of heat rash, but it’s also the least common. It often happens after a period of prolonged exercise when you sweat more than usual. If the sweat gets trapped in your skin, you may develop a series of larger, firm, reddish-colored bumps. This type of heat rash is more common in adults than children or babies.
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Unlike heat rash which usually clears up fairly quickly, eczema is a long-term, chronic condition that needs treatment and ongoing management.

It tends to develop in infancy or childhood, and is very common in children. In fact, it affects between 10 and 20 percent of children.

Eczema, which is also known as atopic dermatitis, can and does persist into adulthood for more than 16 million adults. If you first developed eczema in childhood, you may have learned to recognize the hallmarks of an eczema flare-up by now.

But it might be harder for an adult who develops what dermatologists call adult-onset atopic dermatitis. It may also be more challenging for a parent who’s not sure whether their child has eczema or just a heat rash.

There are actually many different kinds of eczema. In fact, experts tend to group them into seven specific types.

The most common is called atopic dermatitis. It affects more than 26 million people in the United States. Atopic dermatitis tends to develop in the first 6 months of life, but it can also develop later.

Atopic dermatitis is characterized by dry, itchy skin. The color of the rash tends to be:

  • reddish in people with lighter skin tones
  • brown or gray in people with darker skin

Sometimes your skin will get thicker in patches where the rash appears. It has a genetic component, but your immune system and environmental triggers may also play a role.

According to the National Eczema Association, the other six types of eczema include:

  • Contact dermatitis. With contact dermatitis, a rash develops in the area where your skin comes into contact with a substance that irritates it, for instance a product that contains chemicals or dyes that you’re allergic to.
  • Dyshidrotic eczema. People who develop dyshidrotic eczema tend to get itchy blisters on the soles of their feet and palms of their hands.
  • Neurodermatitis. Also known as lichen simplex chronicus, this type of eczema starts with one or two itchy patches of skin that get itchier and itchier. Repeated scratching can make the skin thicker (but usually still itchy).
  • Seborrheic dermatitis. Seborrheic dermatitis tends to develop in areas that are rich in oil glands, like the scalp, nose and upper back. It typically shows up as red, scaly patches. In babies, greasy, scaly patches that are commonly referred to as cradle cap, is a form of this type of eczema.
  • Stasis dermatitis. Poor circulation to the lower legs is usually the culprit for stasis dermatitis. It may start out with just small spots of discoloration and some ankle swelling and progress to larger areas of swelling, along with redness or scaling.
  • Nummular eczema. This type of eczema is characterized by round, oozy patches on the skin. It can easily get infected, so treatment is usually necessary.

It’s important to note that different kinds of eczema can overlap. In other words, you could have more than one kind at the same time. And they may require different treatment or management strategies.

Because heat rash and eczema can look similar to each other, it’s not always easy to tell them apart. If you can’t tell by looking at the rash, it’s important to consider the following factors.

Heat rash vs. eczema

  • Location. Eczema can appear anywhere, but it often develops behind the knees, in the inner part of the elbows, on your hands, and on your scalp and head. Heat rash is more prevalent in the folds of your skin or areas where your clothing rubs up against your skin.
  • Timing. Have you been sweating a lot, or experienced hot, humid conditions? If so, it could be a heat rash.
  • Triggers. Certain things can trigger an eczema flare-up. For example, if you’ve been exposed to a known trigger, like a fragrance, chemical, food allergy, pollen, or an emotional stressor, you may be having an eczema flare-up.
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Once you know what type of skin condition you’re dealing with, you can take steps to treat it appropriately.

How to treat heat rash

The good news is that heat rash typically goes away on its own. You might be able to speed up the process by stopping whatever activity you’re engaged in and cooling off.

Remove any heavy or sweaty clothing that may be trapping sweat in your skin. Take a cool shower to help lower your body temperature. This can also help remove any dirt and oils from the surface of your skin that may be clogging your pores.

For a more intense case of prickly heat, you may want to apply a calamine lotion or a low-dose hydrocortisone cream.

How to treat eczema

The treatment for eczema can vary based on the type of eczema you have and how severe it is.

For a typical case of atopic dermatitis, your doctor may suggest applying a moisturizer to the affected areas of skin several times per day. You may also benefit from applying a topical corticosteroid or taking an antihistamine if they’re experiencing a lot of itching.

With most cases of heat rash, once you start cooling off, the rash will likely start to improve. But if it doesn’t, you may want to contact your healthcare professional, especially if the rash is accompanied by other symptoms such as:

With eczema, let your doctor or healthcare professional know if you think you’re developing an infection. If you scratch an itchy patch and it starts bleeding, there’s a chance that the open wound could get infected. If you notice pus oozing from a lesion, be sure to get it checked out by a doctor.

If your eczema develops in adulthood, consider making an appointment with a healthcare professional to get it checked out. They will examine the rash carefully and may do some tests to rule out other possible causes.

If you’re a new parent, it’s helpful to know that newborns often develop a variety of different types of rashes. Seborrheic dermatitis is very common in babies, and heat rash can be, too. Most kinds of rashes can be easily dealt with at home. But if you’re concerned and aren’t sure what to do, go ahead and contact your child’s doctor to get some guidance.

Although heat rash and eczema aren’t always preventable, there are some steps you can take to lower your risk of these skin rashes.

How to prevent heat rash

The best way to prevent heat rash is to avoid sweating. This may be easier said than done, especially if you live in a hot, humid climate. After all, sweating is your body’s natural way of keeping you cool in warm conditions.

But there are some ways to reduce sweating and reduce the chances of a rash developing.

  • Wear loose, lightweight clothing and avoid clothing that that’s too tight or that rubs up against your skin.
  • Remove sweaty clothes that are close to your skin.
  • Limit the use of ointments or heavy moisturizers that can block your pores.
  • Try to spend most of your time in the shade or inside an air-conditioned space on hot days.
  • Take cool baths or showers on a regular basis.

How to prevent eczema

Although you can’t prevent eczema, you can reduce the likelihood that you (or your child) will experience an eczema flare-up or exacerbation.

First, try to figure out what your specific triggers are, and then do your best to avoid them. Other steps you can take to try and prevent an eczema flare-up include the following:

  • Avoid strongly scented soaps and detergents, which can irritate your skin.
  • Try to keep your home free of allergens like dust, pollen, mold, and pet dander.
  • Try to keep your stress levels in check.
  • Opt for lukewarm baths or showers instead of hot ones.
  • Don’t scrub your skin in the tub or shower.
  • Find a spot in the shade to stay cool on a hot day.
  • Wear sunscreen and protective clothing outdoors.

With babies, children, and even adults, it can be challenging to determine if you’re dealing with a heat rash or eczema.

If you’re not sure, a good rule of thumb is to get yourself or your child out of the heat into a cooler environment and to watch how the skin reacts. If the rash starts to improve in a day or two, it’s more likely heat rash.

If the rash persists or you notice other symptoms, contact your healthcare provider to get the right diagnosis and treatment.