Selena Gomez Reveals She Has Lupus ... but What Is It, Exactly?

People with the chronic autoimmune disease need to modify their lifestyles to manage the condition— which Gomez did amid rehab rumors last year. (Photo: Getty Images)

Selena Gomez made a startling revelation in a new interview: She has lupus.

“I was diagnosed with lupus, and I’ve been through chemotherapy,” she told Billboard magazine. The 23-year-old recently took a break from the spotlight, which she says happened so that she could seek medical care for her condition.

“That’s what my break was really about. I could’ve had a stroke,” she continued.

At the time — in late 2013 and early 2014 — Gomez canceled the Asian and Australian legs of her Stars Dance tour to take some time for herself. This break fueled media rumors that she was battling addiction.

Gomez on the cover of this week’s Billboard magazine, on stands Thursday, Oct. 8. (Photo: Billboard magazine)

“I wanted so badly to say, ‘You guys have no idea. I’m in chemotherapy. You’re assholes,’” she said. “I locked myself away until I was confident and comfortable again.”

Gomez credits her close friend Taylor Swift with helping her through the tough time. “Taylor makes me feel empowered, like I can trust new people,” she told Billboard. “The way she cares about women is so adamant. It’s pulling me out of my shell.”

Gomez and Swift pose with their squad at the 2015 MTV Video Music Awards in late August. (Photo: Getty Images)

An estimated 1.5 million Americans have lupus, according to the Lupus Foundation of America. The disease can impact anyone, but 90 percent of the people diagnosed with lupus are women — and most develop it between the ages of 15 and 44.

Nick Cannon, Seal, and Toni Braxton also suffer from lupus. But what is it, exactly?

Lupus is a chronic autoimmune disease that can damage any part of a person’s body, Howard R. Smith, MD, director of the Lupus Clinic at the Cleveland Clinic, tells Yahoo Health.

With lupus, something goes wrong with your immune system. The immune system of a lupus sufferer can’t differentiate between bacteria, viruses, germs, and the person’s healthy tissue, Smith explains. As a result, the immune system attacks and destroys that healthy tissue.

While lupus has many manifestations (it can involve the brain, heart, lungs, kidneys, skin, muscles, blood vessels, and more), Smith says about three out of four people experience issues with their skin and joints.

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Smith admits the disease can be confusing for people who aren’t experts, because they may have symptoms that don’t “match up,” like kidney disease and a facial rash.

However, he says, people tend to have certain symptoms like a “butterfly” rash (a facial rash on both cheeks that stretches across the bridge of the nose), sores in the nose, joint pain, and skin and hair loss.

Why are so many lupus sufferers women of child-bearing age?

Smith says experts aren’t totally sure but think hormones like estrogen play a big role. “Estrogens seem to make the disease worse,” he says, noting that the disease often becomes worse in pregnant women.

Genetics may also play a role in whether a person develops lupus, Smith says, and women of color have an increased chance of developing the disease.

There are also environmental factors. For example, lupus patients are very prone to developing rashes if they go out in the sun.

Unfortunately, experts don’t know what sets lupus off. “We’re just not sure,” Smith says. “It might just be that there’s a predisposition, genetics, and something sets it off. Sometimes it’s sun exposure that is the immediate trigger, but it could be a virus that sets off the immune system. It’s probably sitting there dormant for a while.”

Lupus is treatable, but the treatment depends on what form a person’s lupus takes. Some who have only a facial rash will take medicines that calm down the immune system. Others, like Gomez, will need to undergo chemotherapy to “knock down” the immune system, Smith says. (Chemotherapy can cause hair loss in lupus patients, says Smith, but it doesn’t always happen.)

But, despite treatment options available, people aren’t necessarily cured of lupus. “We don’t talk about ‘cure’ in general,” Smith says. “We try to get people to have a relatively well-controlled disease.”

Occasionally or rarely, lupus goes into a long remission, Smith says, and sometimes it will “burn itself out” after 15 years or so. But most patients have a chronic disease that may not be life-threatening but makes them modify their lifestyle.

“The majority of patients who have lupus lead a relatively normal lifestyle,” Smith says. “They may not feel 100 percent, and they may have fatigue and arthritis.”

Concerned you may have lupus? See your primary-care physician first. Your doctor can do some initial screening tests and may refer you to a rheumatologist for further diagnosis and treatment.

For more information on lupus, please visit the Lupus Foundation of America’s website.

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Correction: This story previously incorrectly stated that lupus is not life-threatening. While many people with lupus can expect to live a normal lifespan, it can be life-threatening for certain patients, especially those who experience a severe flare-up.