Image copyright AFP Image caption Demi Lovato's fans say the singer's battles have helped them with their own struggles

US pop singer Demi Lovato has issued her first statement after she was taken to hospital for a suspected drug overdose last month.

In an Instagram post, Lovato, 25, said: "I have always been transparent about my journey with addiction".

"This illness is not something that... fades with time. It is something I must continue to overcome," she said.

Lovato has previously spoken about her struggle with addiction, bipolar and eating disorders.

In her statement, the singer thanked her family and medics at Los Angeles' Cedars-Sinai hospital, saying that "without them I wouldn't be here writing this letter to all of you".

"I want to thank God for keeping me alive and well. To my fans, I am forever grateful for all your love and support."

She said she now needed "time to heal and focus on my sobriety and road to recovery", adding that "I will keep fighting".

Lovato, whose biggest worldwide hits include Skyscraper, Cool For The Summer and Sorry Not Sorry, has struggled with substance abuse for years, and was feared to have relapsed in recent weeks.

Last month she cancelled her show at London's O2 arena, announcing the news on Twitter hours before the concert was due to begin.

And in a recently released single, Sober, she sings: "Mommy, I'm so sorry I'm not sober anymore. And daddy please forgive me for the drinks spilled on the floor."

The song ends with the lines: "I'm sorry that I'm here again, I promise I'll get help/It wasn't my intention, I'm sorry to myself."

Media playback is unsupported on your device Media caption Demi Lovato helps woman overcome depression and self-harm

Her fans say the singer's battles - often documented in her music - have helped them with their own struggles.

Raised in Dallas, Texas, Lovato first entered the spotlight on the children's TV series Barney & Friends.

She appeared alongside the Jonas Brothers in the 2008 Disney Channel movie Camp Rock.

Lovato released her first studio album, Don't Forget, in 2008.

In a YouTube documentary, Simply Complicated, released last October, Lovato revealed her drug use began when she first tried cocaine at the age of 17.