Sometimes art imitates life, and sometimes life imitates art, and sometimes art can even save your life. Lucky for this writer, I learned when to go to the emergency room for a skin condition mere hours before I actually needed to use the information.While writing this piece, I got a rash on my arm. At first I wondered: Is this a case of hypochondria—like med students who worry they have the disease they’re studying that week?

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But when I woke up in the middle of the night with a rash that had doubled in size, was warm to the touch, and was neon red, I knew I had to act fast. The irony that I was writing a piece on rashes did provide some comic relief, but it didn’t stop me from taking my symptoms seriously.Some rashes, like the one I had, demand your immediate attention. There are a few important symptoms to look out for: swelling, redness, fever, a size larger than the palm of your hand, disruption of sleep, pain, blisters, pus and an aggressive onset.

If you have any combination of those symptoms, pick up the phone right away and call your dermatologist. There’s a simple trick to getting the care you may need, as Boston-area dermatologist Elissa Lunder, M.D., recommends, “If it’s bad, get past the front desk by saying, ‘I really need to talk to a nurse.”’ An RN can help you assess the severity and insist you get squeezed into the dermatologist’s schedule.If you can’t get in at the dermatologist, contact your regular doctor. Skin conditions are actually one of the most common reasons for an office visit.

“Many GP’s know a lot about dermatology,” assures dermatologist Adarsh Mudgil, M.D., a professor at Mount Sinai School of Medicine in New York City. “And if they don’t know, they’ll send you to a dermatologist. Then, we’ll get the patient in right away.”Another important risk factor that requires you to act fast is if you just started taking a new medication or antibiotic. If you fall into that category, “You need to call your doctor ASAP to make sure it’s not a drug rash,” Dr. Lunder adds. That kind of rash could be the sign of a larger problem or an allergy you’d want to nip in the bud.

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With severe symptoms, timing is everything. For example, if it’s the middle of the night, and your rash is keeping you up, “Go to the emergency room!” Dr. Lunder advises. Do not wait to call for an appointment the next day. Motivating myself to go to the hospital in the wee hours of the morning was the smartest decision I made. The rash, which turned out to be cellulitis, a bacterial infection in the skin, went from my thumb and streaked up through my chest. Because it was swelling at such a rapid rate, I was actually at risk of losing my hand or it spreading to other organs. But thankfully, I had this excellent advice and sought care immediately.Even if you’re typically in good health, never write off a rash, because it can have a real risk. “There are a lot of infectious diseases that have skin manifestations as well,” as Dr. Mudgil points out, “Fever and a rash can be very serious.”

Especially if you have other underlying medical issues, you must view the rash through the lens of your overall health.  If you’re diabetic, undergoing chemotherapy, are HIV positive or your immune system is otherwise suppressed, you should be seen immediately, even if it means a trip to the emergency room.Location can also play a factor. This probably goes without saying, but if a rash appears on your genitals or on your face, don’t lollygag, get to a doctor—especially if you play contact sports! And yes, “contact sports” can also be a euphemism for sex, in this case.“But if you’re a perfectly healthy person and you get a bump on your leg and you want to wait a week to see if it goes away, I think that’s appropriate,” Dr. Mudgil says.

So long as it’s mild and not interfering with your lifestyle, there’s typically not a compelling reason for much concern. If the rash isn’t aggressive, you don’t have to be aggressive either.However, if something pops up on your skin and it’s bothering you, you shouldn’t hesitate to schedule an appointment. Even if your symptoms don’t seem severe, Dr. Mudgil assures, “You’re never crying wolf. There’s no judgment when you come to see a dermatologist.” Dr. Mudgil has seen time and time again, “The worst thing to do is wait and try and diagnose yourself and [play] Google doc. You’ll probably end up freaking yourself out or you’ll just start marching in the wrong direction.” And then, if you use the wrong DIY treatment, you’ll likely just make it worse.

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