Why Do I Keep Breaking Out in Hives?

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I got an itchy rash out of nowhere. I don’t have allergies, so what gives?

Hives are itchy, red welts that usually last for less than 24 hours but may crop up in a different place the next day and the day after that, like a real-life version of whack-a-mole. Their transience makes them unlike bug bites or other rashes, which tend to take up residence in the same spots for days. The lesions sometimes connect to form larger, megahives, which can look “really, really dramatic,” says Marie Leger, M.D., assistant professor of clinical dermatology at Weill Cornell Medicine and a member of the American Academy of Dermatology — in other words, they’re a great conversation starter.

They’re also really common: About 15 to 20 percent of people will experience acute hives in their lifetime, she says, meaning a case that lasts less than six weeks. Really, though, you could have them for a single day. Some unlucky souls have bouts of hives (technical name urticaria) that stick around for longer than six weeks, and those are considered chronic cases. Chronic hives are much less common — they happen in about one or 2 percent of people — but Leger says women are more likely to get them than men. Lucky us.

While it is possible to figure out why you’re an itchy mess, don’t count on hard answers. A dermatologist or allergist would get a very detailed history, including how long the lesions lasted, if you’ve been stressed out, if they were worse after exposure to heat, cold, or pressure, or after exercise or taking aspirin, if you’ve started any new medicines, eaten new foods, or been sick or traveled recently.

It’s easier to identify the triggers for acute cases than chronic ones, she says. “If someone were to come to me and they’d had hives, or something that sounded like hives, for six weeks, I’d still ask them all those questions but you’re less likely to be able to pinpoint exactly what’s causing it,” says Dr. Leger, who’s also an assistant attending dermatologist at New York–Presbyterian Hospital.

Frankly, she doesn’t see many people with acute cases in her office. Either the hives go away on their own, or people are freaked out enough that they go right to urgent care or the ER rather than waiting for an appointment. She sees a lot of the chronic-hive people, though, and she often tests them for antibodies to the immunoglobulin E (IgE) receptor. If a person tests positive, and she says many do, then doctors know that their chronic hives are caused by IgE making the skin’s mast cells release inflammation-causing histamines. Their body is having an autoimmune response for basically no reason — which is annoying, but sometimes just having this little nugget of an explanation can be reassuring.

It’s better than the alternative answer: “Often we’ll look for [the antibody] and we won’t find it. Most often, the patients that I treat with chronic urticaria, we can’t tell them why they have it and it drives them nuts,” she says. “[Hives are] really unpredictable and nobody likes unpredictable things. Part of treating these very lovely but very frustrated patients is getting people to just kind of let go. You’re often not going to find what causes them, but it’s okay, we can still treat them.”

Regardless of whether hives are acute, chronic, or autoimmune-related, the first-line treatment is good old antihistamines, which are safe, well-tolerated, and pretty darn cheap. Some patients take a multi-antihistamine cocktail, some rely on the pills plus phototherapy, and others take a prescription drug called Xolair, which blocks IgE and was originally approved as an asthma treatment.

Dr. Leger warns that if your itchy bumps last longer than 24 hours, leave marks, and are painful, they may not be hives but rather a sign of urticarial vasculitis, which is a bigger deal. And if your hives come with a side of swelling of the lips or tongue and difficulty breathing or speaking, it could be a condition called angioedema, which might mean you’d need to carry an EpiPen. (But only if you experience fainting or swelling that impedes your breathing.)

Usually hives are more of a nuisance than anything, but some people get them so often that they’d really love to trade in their epidermis. She knows it’s frustrating — and described itch as a “form of torture” — but says chronic sufferers need to manage their quick-fix expectations.

“You’ll have to work pretty closely with your doctor over a course of sometimes several months. We have some patients that we see over the course of several years to help them keep their hives under control,” she says. “But there’s so many treatment options out there we can definitely find something that helps everyone.”

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