A spokesman for the Los Angeles Fire Department said they received a call at 11.22am for an "medical emergency" and took a 25-year-old woman from a property in Hollywood to a local hospital.
The report indicated that the "Sorry, Not Sorry" singer was found unconscious inside her Hollywood Hills home on Tuesday.
Simply Complicated, Lovato revealed that the last night she drank alcohol - in March 2012 - she was so hungover the next day that she nearly couldn't sing for a scheduled performance on American Idol.
"And daddy, please forgive me for the drinks spilled on the floor". CBS News reports that her recent song "Sober" is about a relapse after six years of sobriety where she apologizes for letting down her family and fans.
ET's Katie Krause was on the red carpet at the Fox singing competition's season finale on Tuesday, where she caught up with judges Meghan Trainor and DJ Khaled, who both sent their best wishes to the talented performer. "In light of recent reports, we have made a decision to replace the episode of BEAT SHAZAM with another all-new episode".
The star recently split with her life coach, Mike Bayer, as well as letting go several other members of her team.
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Lovato, who has some 69 million followers on Instagram, was in the midst of a USA tour and was due to perform in Atlantic City, New Jersey, on Thursday. Their occupants did not stop to speak to reporters.
Her hospitalization became the top trending item on Twitter on Tuesday, with fans and celebrities expressing concern and support. "Praying for her right now, addiction is a terrifying disease".
A final tweet from singer Halsey - who famously criticised Demi for her take on same-sex relationships in hit song Cool For The Summer - also showed her support.
The "Sorry Not Sorry" singer, 25, has struggled with substance abuse for years.