Singer Lily Allen tweeted, "Poor lovely spirit @ddlovato I hope she's ok, and that she makes a full recovery soon".
"Sober" did not reveal the nature of Lovato's relapse.
"Mama, I'm so sorry I'm not sober anymore / And daddy please forgive me for the drinks spilled on the floor", she sang.
In the second verse, Lovato apologises to the fans who've "watched her fall again" - "I wanna be a role model, but I'm only human".
"We have made a decision to replace the episode of Beat Shazam with another all-new episode".
It was confirmed on Tuesday afternoon that Demi had been rushed to the hospital after being found unconscious in her Hollywood home. Live Nation did not immediately respond to CNN's request for comment.
Moscow slams USA over arrest of Russian agent
Federal Bureau of Investigation agents arrested Butina on Sunday as she was apparently preparing to move to South Dakota. In seeking her detention, prosecutors said that her "legal status in the United States is predicated on deception".
Lovato, who began her acting career on the popular children's series Barney & Friends, rose to fame on the Disney Channel. "And I anxious a lot, as her friend, that something was going to leak or somebody would somehow take that and use it negatively against her, or to make her seem like she's got a secret", she said. Following the news that the "Skyscraper" singer was awake and with her family, Lady Gaga wrote her own touching post dedicated to Demi.
The pop star made the revelation about the setback in a single, "Sober", released late last month. Her debut album Don't Forget sold over 500,000 copies, while the follow-up Here We Go Again debuted at No 1 on the Billboard 200.
This is a breaking news story and will be updated.
Demi Lovato opened up about her previous addiction troubles in a 2017 documentary.
'I've never loved anybody like I loved Wilmer and I still love him, ' she said.
"I knew at a young age that some of my behaviours were a problem", she said, but added: "I wasn't in a place where I could quit by myself".
- Pompeo, Haley step up pressure to support Trump's talks on North Korea
- British Open at a glance
- GoFundMe campaign set up to get Kylie Jenner to 1 billion dollars
- Gianfranco Zola returns to Chelsea as Maurizio Sarri's assistant
- China’s U.S. trade surplus hits record on rush to beat tariffs
- Duchess of Cambridge beams in white at Prince Louis' christening
- Trump OK'd disclosure of Russian indictments
- Jupiter's moon count reaches 79, including tiny 'oddball'
- Galaxy J2 Core is Samsung’s first Android Go smartphone
- Wimbledon 2018 men's semi-final: Novak Djokovic v Rafael Nadal