The site says Lovato was unconscious when emergency services arrived, and law enforcement sources say that Narcan was administered on the scene. Narcan is used to counteract opioids.
Lovato was at her Hollywood Hills home at the time.
“Extra” has learned that the Los Angeles Police Department received the 911 call before noon on Tuesday.
A source tells Variety she is now "stable." Earlier in the day, her aunt, Kerissa Dunn, tweeted that Lovato was "awake and responsive," but later deleted the message.
Following the news, Demi's appearance on Tuesday's episode of "Beat Shazam" was pulled, and her July 26 concert in Atlantic City was canceled.
Less than 24 hours before the emergency, she posted a selfie on Instagram.
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Lovato has been open about her battle with addiction, and has sought treatment in the past.
Demi revealed last month that she had fallen off the wagon when she released a new song called “Sober.”
When "Extra" caught up with Demi at an event in NYC in March 2017, she opened up about her sobriety. “My fans are part of the reason why I'm sober, they hold me accountable. If it weren't for my friends, family, and fans, I wouldn't be here today.”
She added, “My ups and downs keep me strong.”
Lovato said she also wanted to help others. “Being able to help people in recovery is something I'm passionate about.”