Selena Gomez may be most famous for her on-again, off-again relationship with the Biebs, but she’s now shedding light on a disease that most people know very little about: lupus. In a December 3 interview with Billboard, the 23-year-old singer opens up about her recovery from the autoimmune disase, which, according to the Lupus Foundation of America, affects more than 1.5 million people in the U.S.

“It has been overwhelming, and the response has been very supportive, which is nice—but it still makes me a little uncomfortable,” says Selena. “I waited for the right time to talk about it because I am in a great place and I’m very healthy. I’m not trying to be loud about it: It was time to use my platform to help.”

If you have an autoimmune diseases like lupus, your immune system attacks and destroys healthy tissue in your body. According to the Lupus Foundation of America, lupus most often occurs in women between the ages of 15 to 44, and women of color are two to three more times as likely than white women to develop the disease. Some of the most common symptoms include a butterfly-shaped rash across the cheeks, extreme fatigue, headaches, painful or swollen joints, anemia, and hair loss.

Selena first talked about her health struggles in an October interview with the music mag. Back then, she revealed that she’d had chemotherapy to treat the disease, telling Billboard that that’s the reason she took a break from touring and entered rehab in January 2014.

“I was diagnosed with [autoimmune disease] lupus, and I’ve been through chemotherapy,” she says in the October interview. “That’s what my break was really about. I could’ve had a stroke. I wanted so badly to say, ‘You guys have no idea. I’m in chemotherapy. You’re assholes.’ But I was angry I even felt the need to say that. It’s awful walking into a restaurant and having the whole room look at you, knowing what they’re saying. I locked myself away until I was confident and comfortable again.”