Celebrity with lupus: Selena Gomez underwent chemo for autoimmune disease back in 2013

Selena Gomez announced in an interview that she is battling lupus, a chronic autoimmune disease. The 23-year-old singer lashed out against the rumors that she had an addiction problem as she got chemotherapy treatment for the disease.

"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 said in an interview with Billboard.  "I wanted so badly to say, 'You guys have no idea. I'm in chemotherapy. You're assholes.' I locked myself away until I was confident and comfortable again."

Lupus is an autoimmune disease which can affect any part of the body including lungs, kidneys, skin, joints, internal organs and other blood vessels. According to Medical News Today, there is no single cause for lupus or rather it is unclear how it develops. The lupus wreaks havoc by making the body's immune system produce antibodies to fight healthy tissue. Signs and symptoms of lupus include fevers, headaches, unusual hair loss, swollen glands, fatigue, skin rashes, swelling joints, and chest pain during deep breaths to name a few.

While chemotherapy is popularly known to be given to cancer patients, Gomez is taking a lower dosage than cancer chemotherapy treatment. However, side effects such as nausea and diarrhea can still affect the lupus patient.

Dr. Joan Merrill of the Lupus Foundation of America explained that chemotherapy can help suppress the immune system which causes the body to go haywire.

"What [chemotherapy drugs] do is they kill any of the cells in the body that are rapidly dividing," Dr. Merrill said, via ABC News.

She added that a person with lupus have rapidly dividing immune cells which causes inflammation in the body.

"Many of the symptoms of lupus are like a virus. It's your body thinking it's being attacked and needs to fight back," Dr. Merrill explained.

According to the Lupus Foundation of America, there are 1.5 million Americans suffering from the disease and at least 5 million people around the world. The disease is common among women and still more common among colored women including Asians, Native Americans, Hispanics, Native Americans, Alaska Natives, and Pacific Islanders than Whites. The disease commonly develops between the ages of 15-44. Lupus often runs in families. 20 percent of people diagnosed with lupus have a direct relative who have lupus or may have lupus in the future. Children born from people with lupus have a five percent increased risk of getting it as well.