7 People on What It’s Really Like to Have Lupus

— -- Selena Gomez is finally opening up about the real reason she took some time off in 2013: The pop star was busy with treatment for lupus.

In a new interview with Billboard, the actress-singer, 23, explained that she underwent chemotherapy for the autoimmune disease amid intense fan and media speculation (some reports said she was in rehab for addiction, adding insult to injury) about why she was keeping a low profile.

“I was diagnosed with lupus, and I’ve been through chemotherapy. That’s what my break was really about. I could’ve had a stroke,” Gomez told the magazine. “I wanted so badly to say, ‘You guys have no idea. I’m in chemotherapy. You’re a–holes.’ I locked myself away until I was confident and comfortable again.”

9 Celebrities With Lupus

What is lupus?Short for systemic lupus erythematosus (SLE), lupus is a chronic autoimmune disease that occurs when the body’s immune system attacks its own healthy organs and tissues— and it can often take years to diagnose. Lupus can also sometimes be mistaken for other illnesses. Why? The symptoms are often non-specific and vary widely, such as fatigue, joint pain, swelling, fever, and rashes, especially what’s called a “butterfly rash,” which stretches across both cheeks and looks like a sunburn.

The inflammation caused by lupus can harm everything from the kidneys, skin, joints, and blood cells, to the lungs, brain, and heart. However, the physical and mental implications of the condition can be vastly different from person to person.

Because lupus is not only tricky to diagnose, but also tricky to understand, we asked several people living with lupus to share what it’s really like, what they wish people knew about this disease, and how they push forward. Here are their stories.

“Many people say that we ‘don’t look sick’ when there is a battle raging inside of us.”— Sharon Harris, 36, founder and president of Lupus Detroit

Harris, who was diagnosed at 23, has experienced it all over the past 13 years: from the “butterfly rash” to swollen joints. She is now recovering from a recent stroke.

“One day, I washed my face and brushed the washcloth across my eyelashes. [It] stopped me dead in my tracks. I was too exhausted to scream but it knocked the life out of me so much so that I had to sit on the edge of the tub to regroup,” Harris says. “My eyelashes hurt—I will never forget that.”

But on the other extreme, Harris says there are days she feels like she can run a marathon. “See, lupus just isn’t a physical disease. It’s also mental. On my good days, my mind is clear and at peace, my movements are fluid.”

Her mantra: Avoid negativity at all costs, and love yourself. “You might be hairless, you may have a butterfly rash, your knuckles may be as swollen as large as lemons, but you still matter.”

9 Symptoms Used to Diagnose Lupus

“I’ve had folks tell me, ‘At least it’s not cancer.'” — Ayanna Dookie, 34, stand-up comedianNov. 9 2012: Dookie will never forget the day she got her official diagnosis of SLE. She didn’t have any of the telltale symptoms of lupus, except for joint pain in her wrist that just wouldn’t go away. It wasn’t until her doctor ordered blood tests that it all lined up.