A source tells PEOPLE that Demi Lovato is 'stable' after being rushed to a Los Angeles hospital following an apparent overdose

Demi Lovato was rushed to a Los Angeles hospital on Tuesday after suffering an apparent overdose and is now “stable,” a source close to the singer tells PEOPLE.

A representative for the Los Angeles Fire Department tells PEOPLE they “transported a 25-year-old female patient to a local hospital,” while the Los Angeles Police Department confirms both departments “responded to a medical emergency” in the area of her Hollywood Hills home.

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Audio of the emergency call obtained by TMZ reveals the pop star was unconscious upon their arrival and revived with Narcan — an emergency medication to reverse the effects of a narcotic overdose. While TMZ reports the overdose is heroin-related, a source close to Lovato claims to PEOPLE that it is not.

Lovato has battled addiction, mental illness and disordered eating for years. In 2010, she entered treatment, where she was treated for bipolar disorder, bulimia, self-harm and addiction. She relapsed after she left the treatment center, then entered a sober living facility for a year.

Image zoom Demi Lovato. Jordan Strauss/Invision/AP/REX/Shutterstock

But even after treatment, insiders say she still struggled with her private pain. “Demi was never really clean and sober from all of her demons,” a source tells PEOPLE. “She has been fighting depression and anxiety for quite some time — and is still in such a dark place. She was sober for a while, but not completely sober for six years.”

Last March, Lovato revealed she celebrated six years of sobriety, but in June she released a new song, “Sober” on which she revealed that she had relapsed.

“Mama, I’m so sorry I’m not sober anymore / And daddy please forgive me for the drinks spilled on the floor,” she sang on the heartbreaking piano ballad. “And I’m sorry for the fans I lost who watched me fall again / I wanna be a role model, but I’m only human.”

RELATED VIDEO: Demi Lovato Reveals She Relapsed After Six Years in New Song ‘Sober’

At the end of the track, Lovato sings: “I’m sorry that I’m here again / I promise I’ll get help / It wasn’t my intention / I’m sorry to myself.”

A source close to the situation tells PEOPLE there have been clear signs that all isn’t well with Lovato’s health. “Things have been a total mess for months. She and her team severed ties, and they played a large part in getting her sober years ago. She hasn’t been in a good place.”

An additional insider also noticed a downturn. “You could tell when Demi was doing well with her sobriety because she wasn’t hanging out at clubs,” the source tells PEOPLE. “She has still very much kept up her work schedule and daily life, but there have definitely been signs that she isn’t doing great with her sobriety.”

Image zoom Demi Lovato. MARK RALSTON/AFP/Getty

Live Nation has confirmed to the Press of Atlantic City that Lovato’s concert scheduled for Thursday in the New Jersey seaside resort town has been canceled.

If you or someone you know is in need of help, please contact the SAMHSA substance abuse helpline at 1-800-662-HELP.