In a post to Instagram, the 25-year-old singer is pictured on a hospital bed and hooked up to tubing right next to kidney donor Francia Raisa. Gomez and Raisa, an actress best known for her role as Adrian Lee in The Secret Life of the American Teenager, are close friends.
In the post, the Texas native addressed her reduced visibility due to her health issues.
"I found out I needed to get a kidney transplant due to my Lupus and was recovering," Gomez said. "It was what I needed to do for my overall health."
Gomez promised followers to reveal more about her health battle. She also thanked her family and doctors before paying tribute to Raisa.
"She gave me the ultimate gift and sacrifice," Gomez said. "I am incredibly blessed."
According to the Lupus Research Alliance, the disorder affects the immune system and can impact many parts of the body, including joints, skin, kidneys, heart, lungs, blood vessels, and brain.
There is no cure for lupus, the organization said.