Do you have heat rash or sun poisoning? Look for these important differences, derms say

With sunny summer weather can come new — or returning — skin rashes, including heat rash and sunburn. At the more severe end, you might even develop sun poisoning.

While these skin reaction have similar names and are related to heat and sun exposure, they are different conditions, Dr. Shasa Hu, associate professor in the department of dermatology and cutaneous surgery at the University of Miami Miller School of Medicine, tells TODAY.com.

People may confuse the signs of a heat rash with those of a sunburn or polymorphic light eruption, a type of sun sensitivity. And it's especially important to know the signs of sun poisoning, which can be severe, so you can get the correct treatment promptly.

Heat rash vs. sun poisoning

Heat rash

A heat rash can form when sweat ducts, found all over your body, are blocked, Dr. Cameron Rokhsar, associate clinical professor of dermatology at Mount Sinai Hospital and dermatologist in private practice in New York, tells TODAY.com.

This causes tiny bumps that look like pustules, Hu explains. And they're actually inflamed sweat glands and clogged pores on the surface of the skin where sweat is unable to come out, she says. The rash may also look like red patches and it is sometimes itchy.

Heat rash is common among babies and young kids who frequently develop it along the diaper line, Hu says. "We see it mainly in babies because their sweat glands are not as well-formed," she adds.

In adults, heat rash shows up during periods of intense sweating, particularly if you’re wearing thick clothing, heavy creams or are in extreme heat. Hu, who practices in Miami, sees heat rash frequently in people who sweat a lot while working out. It's most common for adults to develop the rash on their chest and back, she says.

How to treat it: First, try to cool down your skin by getting out of the heat and taking a cool shower, Rokhsar says.

Hu also recommends using some light physical exfoliation while in the shower, such as a washcloth, "to remove that top layer of cells that's clogging the glands." You can also use a mild chemical exfoliant, like a 2% to 5% salicylic acid wash, also helps remove the dead skin cells, Hu says.

"It's almost as if we're treating acne," she says.

With those tips in mind, the rash should clear up in a day or two — provided you're not picking at it, Hu says. If you pick at the bumps, they may develop into a secondary skin infection or cause hyperpigmentation issues down the line in patients who are prone to those conditions.

"See a doctor when the heat rash is so itchy that you can't stop scratching to avoid long-term scarring or staining of the skin," Hu says. Your doctor or dermatologist can prescribe creams to ease the itchiness.

Sun poisoning

While some might casually refer to a bad sunburn as sun poisoning, they are not the same thing.

"Sun poisoning is really a combination of damage to the skin, excessive UV exposure as well as the body heating up," Hu explains. Typically, your body temperature needs to be kept within a narrow range. But, with sun poisoning, "there's so much heat that your body is not able to sweat fast enough to dissipate the heat," Hu says.

That, coupled with the intense damage to your skin from sun exposure and dehydration, causes a whole-body reaction with flu-like symptoms that can be severe. They may have fever, chills, nausea, headache and other symptoms.

"That can be a medical emergency because, eventually, they'll develop an altered mental state," Hu says. At the most serious end, someone with sun poisoning may become confused and dizzy — as well as severely dehydrated and overheated.

Although people often have a serious sunburn along with sun poisoning, the condition doesn't always cause a skin issue, Hu says.

How to treat it: If you suspect that you or someone you're with has developed sun poisoning, first, get them out of the sun and into a cool (ideally air-conditioned) space, Hu says.

From there, people with systemic sun poisoning symptoms may need to be treated with "at times, aggressive" hydration in the emergency room, she adds.

Polymorphous light eruption

Another sun-related rash that's commonly confused for sun poisoning is polymorphic (or polymorphous) light eruption.

This condition, also called PLE, is essentially an allergic reaction or sensitivity to the sun that causes an itchy, red, bumpy rash, Rokhsar says.

“It is an overreaction to UVB rays of the sun when you haven’t seen it in a while,” Dr. Carolyn Jacob, a dermatologist in private practice in Chicago, tells TODAY.com. The rash is most often found on the forearms, chest and neck.

The reaction is common at the start of the summer when the skin hasn’t been exposed to the sun in quite some time, Jacob adds.

How to treat it: You can use an over-the-counter hydrocortisone cream or an oral antihistamine for immediate relief, Rokhsar says. You should also avoid the sun as much as possible if you notice this rash.

But Rokhsar recommends seeing a dermatologist first to rule out other sun-sensitive rashes rather than immediately going the DIY route. Your dermatologist can also prescribe additional treatments, typically a steroid cream.

Other common summer rashes

Summertime rashes aren't just related to heat or sun. During these warmer months, we're also more likely to encounter bugs and plants that can cause bothersome reactions.

“There’s a lot more opportunity to get into stuff that would cause a rash if the weather is nice,” Jacob says.

Those rashes can include:

• Poison ivy rash, a type of allergic dermatitis. The rash will likely be itchy and may also blister.

• Insect bites, which can look and feel different depending the type of bug that bit you, including mosquitoes, chiggers and more.

• Lyme disease, a tick-borne illness, can come with a bullseye-shaped rash. But not everyone who has Lyme disease will develop the distinctive mark.

When to see a doctor

In many cases, you may be able to manage summer skin rashes at home. Depending on the type of rash, you might be able to ease the itchiness with over-the-counter products or a cool compress.

However, there are a few cases in which it's important to see your doctor or seek medical attention quickly:

• If you've been treating the rash at home and it's getting worse or just not getting better, you should see a doctor or dermatologist to make sure you're treating it correctly.

• If you have systemic symptoms along with the rash, such as a fever or nausea, you should get medical attention.

• If you have a suppressed immune system and develop a rash, you should get checked out because you have a higher risk for certain serious infections.

Even if you these criteria don't apply, you should still get an expert's opinion if your rash is intensely painful, suddenly covers a large part of your body or seems otherwise severe in any way.

This article was originally published on TODAY.com