Singer Demi Lovato spoke out Sunday about her battle with addiction, saying she needed "time to heal and focus on my sobriety" days after she was taken to a Los Angeles hospital for an apparent overdose.

"I have always been transparent about my journey with addiction," the 25-year-old Grammy-nominated recording artist wrote on Instagram. "What I've learned is that this illness is not something that disappears or fades with time. It is something I must continue to overcome and have not done yet."

Lovato, who has spoken openly in the past about her history of drug and alcohol abuse, thanked God, her friends and her fans, saying their positive thoughts and prayers had helped her navigate "this difficult time."

She also thanked her family, team and the staff at Cedars-Sinai Medical Center in Los Angeles that she said had been at her side since she was admitted on July 24.

"Without them I wouldn't be here writing this letter to all of you," Lovato wrote.

"I now need time to heal and focus on my sobriety and road to recovery," she continued. "The love you have all shown me will never be forgotten and I look forward to the day where I can say I came out on the other side. I will keep fighting."

The New Mexico-born performer rose to fame on Disney Channel shows "Camp Rock" and "Sonny with a Chance" before forging a pop career with hits such as "Skyscraper" and "Sorry Not Sorry."

In a 2017 YouTube documentary, "Simply Complicated," Lovato spoke about years of substance abuse, eating disorders and drinking, saying she first started using cocaine when she was 17. She entered rehab at the age of 18 and was diagnosed with bipolar disorder, she said.