Selena Gomez is speaking out about an urgent kidney transplant she underwent over the summer that she's since said was a "life or death" consequence of her lupus.

In an interview with Today this morning (October 30), Gomez chronicled the surgery, and the incredible generosity of good friend and roommate Francia Raisa, who donated the vital organ.

“My kidneys were shutting down. My mentality was to keep going,” she said. “[Raisa] lived with me during this interesting time where my kidneys were just done. That was it, and I didn’t want to ask a single person in my life. The thought of asking someone to do that was really difficult for me. She volunteered and did it. And let alone someone wanting to volunteer, it is incredibly difficult to find a match. The fact that she was a match, I mean that’s unbelievable. That’s not real.”

Gomez said the procedure, itself, was a physical and emotional test that did not go exactly as planned.

“I started to attempt to fall asleep. And in the middle of that process I started hyperventilating and felt so much pain,” she said. “My teeth — I was grinding — I was freaking out. It was a six-hour surgery that they had to do on me and the normal kidney process is two hours. Apparently one of the arteries had flipped. I’m very grateful that there are people who know what to do in that situation.”

Now, Gomez says her health has improved dramatically, and that her lupus is completely at bay.

“It’s really hard to think about or even to swallow,” she said, noting all that's changed. “My energy and my life has been better.”

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