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The 25-year-old has sung about her struggle with addiction in the past.
Pop singer Demi Lovato is in a Los Angeles hospital after a suspected drug overdose, US media report.
The Los Angeles Police Department reportedly responded on Tuesday to a medical emergency in the Hollywood Hills, where Lovato lives.
TMZ, which broke the story, reports she was treated at the scene with Naloxone, an anti-overdose medication, after possibly taking heroin.
The 25-year-old singer was in a stable condition, US media report.
Lovato has struggled with substance abuse for years, and appeared to relapse 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.
In a single released last month, 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."
Demi Lovato helps woman overcome depression and self-harm
The track release followed Lovato marking six years of sobriety in March this year.
She was due to complete the North American leg of her Tell Me You Love Me world tour with a concert in Atlantic City, New Jersey, on Thursday.
Her fans say the singer's battles with bipolar disorder, bulimia and addictionoften documented in her musichave helped them with their own struggles.
The BBC contacted Lovato's representatives on Tuesday, but did not receive an immediate reply.
As reports of her condition spread, there was an outpouring of support on social media from other celebrities and musicians.