CNN confirmed it was Lovato, citing a source close to her family. Dunn earlier asked the singer's fans to send their "thoughts and prayers".
Celebrity news site TMZ released audio of an emergency call in which responders appear to say that Lovato is unconscious and revived with Narcan, a nasal spray used to treat opioid overdoses.
"Her friends and him are just hoping that she gets better and that she can be great and thrive", the source added.
Lovato was in the final days of her current U.S. tour.
Lovato is slated to wrap the second North American leg of her "Tell Me You Love Me" world tour in Atlantic City Thursday.
Los Angeles police were also dispatched, but Officer Carlos Zaragoza said he could not release the woman's identity or condition.
She apologises to her parents before singing in the chorus, "To the ones who never left me / We've been down this road before / I'm so sorry / I'm not sober anymore".
News crews gathered outside Lovato's home in the Hollywood Hills, where vehicles were seen entering and leaving Tuesday afternoon.
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Russian Federation says it is convinced Iran is not building nuclear arms and that Washington is misleading the world . POTUS' tweet was penned in response to Rouhani's address to Iranian diplomats on Sunday.
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That could in turn boost an economy that posted its slowest growth rate in almost two years - 6.7% - in the second quarter. President Donald Trump is continued his threats to impose tariffs on all Chinese imports to the US.
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S. out of the global deal meant to prevent Tehran from developing a nuclear weapon and ordered increased American sanctions. Pompeo blasted the country for corruption and human rights abuses - but also offered direct talks with the regime.
It was sentiment shared by Riverdale actress Lili Reinhart, who recalled the influence the singer had on her in her younger days.
The support for Demi continues as she remains hospitalized.
There was an immediate outpouring of support from the Hollywood community, including pals Ellen DeGeneres, Lily Allen, Lili Reinhart and Adam Lambert, all of whom have been sharing sweet messages for Lovato on social media.
She is now receiving treatment, according to the gossip site.
In an interview with BillBoard, he said: "We could go the manufactured pop machine [route] and try to present this flawless image all the time".
Phil McIntyre, Demi's manager previously insisted Demi speaks openly about her life to "let people in".
"I was just really proud of her that she was honest, because it's really hard to be honest with yourself", Azalea told ET. Youthline (open 24/7) - 0800 376 633. Online chat is available from 7pm to 10pm every day. This service is for children aged 5 to 18. For further information, contact the Mental Health Foundation's free Resource and Information Service (09 623 4812).