Having a skin rash can feel like you’re in a bizarre, dermatological version of Invasion of the Body Snatchers. Your skin is unhappy for some reason, and instead of doing the polite thing—chilling TF out—it’s going to express its displeasure. Boldly. Meet your new rash.
A rash generally indicates that your skin is inflamed in some way, Joshua Zeichner, M.D., a New York City-based board-certified dermatologist and director of cosmetic and clinical research in dermatology at Mount Sinai Medical Center, tells SELF. Broadly, that means your skin is manifesting an immune system response to something your body thinks could harm your health. But there are so many different types of rashes that it can be hard to tell what’s going on with your skin. Dermatologists to the rescue! Here, they offer up several questions that may help you decipher what’s behind your rash—and what to do next.
1. Is your rash itchy?
Itching is a really common side effect of all sorts of rashes, so it’s unlikely that you’ll figure out what’s going on from this symptom alone, Dr. Zeichner says. But some rashes aren’t usually itchy, so this is still a good question to ask yourself.
One example is the rash that can come with angioedema. This skin condition is related to the itchy, raised welts you may know as hives, but it starts deeper under the skin, the Mayo Clinic explains. While hives are known to be maddeningly itchy, angioedema is more likely to cause large, red welts that feel painful or warm, according to the Mayo Clinic. If you’re stumped because you have “hives” that don’t itch, this could be a potential cause.
Even if your rash is itchy, the specifics can help you narrow down what might be causing it. For instance, clusters of tiny, itchy bumps or pimples around hair follicles might indicate a condition known as folliculitis. If you have an itchy rash that comes and goes in the same area, Dr. Zeichner says your doctor may suspect atopic dermatitis (often simply called eczema), a common and chronic skin condition that causes itching and inflammation.
2. Does it have a clear edge?
If your rash has a clear edge, cut-off point, or pattern, the cause is pretty likely something external that is affecting your skin, Misha A. Rosenbach, M.D., associate professor of dermatology at the University of Pennsylvania’s Perelman School of Medicine, tells SELF. That’s as opposed to something internal, like an underlying medical condition, which would be less likely to create a clearly-defined rash.
This can happen due to something like irritant contact dermatitis, or when something inflames the top layer of your skin, according to the American Academy of Dermatology (AAD). Common irritants include nickel, plants like poison ivy, and harsh cleaning agents like bleach. (There’s also allergic contact dermatitis, which is when your immune system loses it in response to something that touches your skin.)
One really weird example of this is phytophotodermatitis, or when chemicals in a plant or plant-based substance you touch interact with sunlight and lead to a superficial skin burn, Dr. Rosenbach says. If you do something like squeeze oranges for fresh OJ then spend a day out in the sun, you might notice a painful, streaky rash on your hands that mimics where the juice touched you, possibly along with swelling and blistering.
3. Does your rash burn?
This can help narrow things down quite a bit. “There aren’t that many rashes that give a burning sensation,” Dr. Zeichner says. You’ll usually get a burning feeling if there is a break in your skin, Dr. Robinson says.
If your skin is red, inflamed, and burning, first check that you don’t have some sort of cut or actual burn. If it really seems like you have a burning rash, Dr. Zeichner says you could be dealing with something like shingles.
Shingles happens due to a varicella-zoster virus infection, according to the Mayo Clinic. (This virus is also to blame for chickenpox, and it can remain dormant in your system for years.) At first, shingles usually causes unpleasant sensations like pain, burning, numbness, and tingling. After a few days, a rash of blisters bubbles up, typically on the left or right side of the abdomen, but occasionally around one eye or one small portion of the neck or face.
Herpes is another potential cause of burning rashes. When herpes shows up around your genitals, it can start as tiny red bumps or white blisters that eventually burst and leak fluid, then scab over, according to the Mayo Clinic. If it emerges around your mouth, this virus can lead to tiny patches of blisters you may know as cold sores, the Mayo Clinic explains. Either way, you can experience some serious burning, itching, tingling, pain, and other uncomfortable symptoms.
4. Is it blistering?
As you may know after trying to break in a pair of shoes, blisters often happen because something is rubbing your skin or otherwise putting too much pressure on your delicate epidermis, according to the U.S. National Library of Medicine. Unfortunately, they also happen because of skin conditions. In fact, blisters can often bead up due to dermatological issues, because a long list of conditions may cause this symptom.
A blister-filled rash could be due to eczema, irritant or allergic contact dermatitis, shingles, and herpes. This can also happen due to a skin infection such as cellulitis, which occurs when bacteria (often Streptococcus or Staphylococcus) worm their way into your body through a crack in your skin, according to the Mayo Clinic. In addition to blisters, your skin might be red, swollen, warm, painful, and otherwise sending you signs that something is wrong.
5. Is your rash scaly?
In a perfect world, your skin cells will naturally bow out when their job is done, shedding in order to allow new, healthy cells to rise to the surface. (Fun fact, per the AAD: The human body typically sheds 30,000 to 40,000 old skin cells every day.) But sometimes this process doesn’t go as smoothly as it should.
“Certain rashes can appear scaly because this natural exfoliating process has been affected,” Dr. Robinson says. This is generally because your old skin cells aren’t shedding properly or your skin is overproducing new cells, she explains. This can happen with eczema, which we’ve discussed above, and also with psoriasis. This chronic condition can present in a few different ways, but the most common—plaque psoriasis—causes thick, raised, dry, scaly patches to form on the skin, the Mayo Clinic explains.
6. Have you had this rash before?
The answer to this question can help you and your doctor figure out what’s triggering the rash. In some cases, chronic skin conditions like eczema or psoriasis are to blame, Dr. Zeichner says. But repeated rashes can also be a sign that continued exposure to something external is setting off your skin.
For example, if you find that you’ve been getting a rash when you wear one specific necklace, you could be allergic to a metal like nickel.
7. Have you tried a new cosmetic recently?
Contact dermatitis often crops up in response to products like soap, lotion, and makeup, Dr. Robinson says. Ask yourself if you’ve added anything new to your routine, but also keep this tricky fact in mind: You can develop this reaction to certain products even if you’ve been using them for ages. Sometimes it takes many exposures for your body to begin showing signs of irritant or allergic contact dermatitis.
If you have a condition like eczema that can cause sensitive skin (or you have sensitive skin in general), you may be more prone to developing rashes in response to what you put on your face and body. If you don’t think you have any underlying skin condition and suspect that products you use are causing your rash, contact dermatitis is probably to blame.
8. Could it be related to the heat?
You can wind up with a heat rash from being in hotter temperatures, the Mayo Clinic explains. This happens when your sweat ducts become clogged, so moisture gets caught under your skin.
In a mild case of heat rash, you may just experience a swath of superficial, clear blisters on the top of your skin, the Mayo Clinic says. More involved cases can cause prickly, itchy red bumps, pus-filled sacs, and hard, skin-toned lesions that look a lot like goosebumps. Luckily, heat rash usually goes away after a few days of keeping your skin cool and stay out of the heat, but you should call your doctor if it lasts longer than that or seems to be getting worse, the Mayo Clinic says.
Heat can also exacerbate some skin conditions like rosacea. This health issue causes reddened facial skin and sometimes acne-like bumps. “Rosacea is a condition where the skin on the face is extra sensitive to the environment and overly reactive to triggers such as spicy foods, emotional stress, alcohol, and heat,” Dr. Zeichner says.
9. Do you have a fever?
If you have a fever along with your rash, it’s a good idea to get checked out by a medical professional, Dr. Rosenbach says. You could be having a serious allergic reaction to something like a medication, according to the Mayo Clinic. This combination of symptoms could also indicate an infection like shingles, mononucleosis, or even measles, according to the AAD.
Don’t hesitate to see your doctor for “just” a rash.
You know your body best. If any symptom feels concerning enough that you’re tempted to see a doctor, that’s a sign that you probably should seek medical advice.
Plus, even if you go through all of the above questions, it can be tough to decode a rash on your own. Luckily, dermatologists are well-versed in rashes. Seeing one can get you one step closer to putting your rash behind you.