Selena Gomez made headlines today when she revealed that her time in rehab was to recover from chemotherapy, which she underwent to treat lupus. Selena Gomez isn't the only celebrity dealing with the chronic autoimmune disease, with famous names like Nick Cannon and Seal joining her battle.

According to MSN.com, about 1.5 million people in the United States have lupus, a disease that causes the body's immune system to attack its own tissues and organs.

Symptoms vary from person to person but can include fatigue, joint pain, swelling, rashes, and fever. The condition can harm the skin, kidneys, heart, nervous system, blood cells, and more.

Women of color are two to three times more likely than white women to develop lupus, according to Dawn Isherwood, a health educator with the Lupus Foundation of America.

Nick Cannon was hospitalized in 2012 for kidney failure and a few weeks later was treated for blood clots in his lungs. He was soon diagnosed with lupus.

He served as the Grand Marshal for the Lupus Foundation of America's Walk to End Lupus Now in Washington, DC, in 2014. "I have lupus, but lupus doesn't have me," he said in an interview. "I'm one of those people who wants to wave the flag and say, you can win this fight."

Many people wonder about the scars on Seal's face, but few know that they are the result of discoid lupus erythematosus, a type of lupus involving only the skin. Discoid lupus typically causes sores on the face and scalp, hair loss, and sensitivity to ultraviolet light and sun exposure.

Toni Braxton was diagnosed with lupus in 2008 and has been outspoken about the weight gain sometimes associated with the treatment of the disease, which involves corticosteroids.

She tweeted in November 2011: "Lupus medication actually causes most women to gain weight. But we're still fabulous! I'm going to work it on out."

Snoop Dogg's daughter, Cori Broadus, developed symptoms of lupus like lightening of her skin, hair loss, and dramatic weight loss in 2005 when she was just six years old. A

"I can't stay in the sun long, but I feel good most of the time," she told PEOPLE magazine in 2010.