Selena Gomez Reveals Intense Details About Her Life-Saving Kidney Transplant

Selena Gomez is opening up about her life-threatening health scare and her emotional journey to [...]

Selena Gomez is opening up about her life-threatening health scare and her emotional journey to taking a friend's kidney like never before.

The actress-turned-pop star underwent a life-saving kidney transplant over the summer as a result of her chronic battle with lupus, an autoimmune disease in which the immune system attacks its own tissues.

In her first interview since the transplant, the 25-year-old recalled to NBC News the difficult decision she faced after doctors noticed her kidneys were failing.

"My kidneys were just done. That was it and I didn't want to ask a single person in my life," she told host Savannah Guthrie in a clip of the exclusive interview. "And she volunteered and did it."

Her hero was The Secret Life of the American Teenager actress and close friend Francia Raisa, 29, who offered to donate her kidney to Gomez.

The "Bad Liar" singer has no doubt that Raisa's brave, selfless act saved her life.

"Because she did. That's it," Gomez admitted. "I guess I got to the point where it was really kind of life or death."

After keeping out of the spotlight over the summer, Gomez announced on Instagram in September that she had undergone the transplant. She revealed the news with a photo holding hands with Raisa in their side-by-side hospital beds, and another of her scar.

"So I found out I needed to get a kidney transplant due to my Lupus and was recovering," Gomez shared to explain her absence to fans. "It was what I needed to do for my overall health."

The singer thanked her team of doctors and her family for their support throughout her journey, then gave a special shout-out to her donor.

"And finally, there aren't words to describe how I can possibly thank my beautiful friend Francia Raisa. She gave me the ultimate gift and sacrifice by donating her kidney to me," Gomez wrote. "I am incredibly blessed. I love you so much sis. Lupus continues to be very misunderstood but progress is being made."

The actress first revealed her lupus diagnosis in an interview with Billboard in October 2015 and told the magazine she was undergoing chemotherapy to treat the disease.

Her illness also caused "anxiety, panic attacks and depression," she told PEOPLE, and decided to take a career break in August 2016.

Gomez opened up further about her journey and her kidney transplant with Raisa in a full interview which airs Monday and Tuesday on the Today show.