According to the American celebrity gossip website TMZ, the former Disney star was taken ill at her home in the Hollywood hills on Tuesday (24 July).
Her spokesperson has since confirmed the star is “awake” and is with her family at Cedars-Sinai Medical Center in Los Angeles.
Stars from the entertainment world have taken to Twitter to send their love and support to Demi.
Lady Gaga wrote: “We should all wrap our arms of love around Demi Lovato. I am so happy you’re alive. Thank God. If I know my monsters as well as I believe I do, we all wish you self-compassion and inner peace. And may you receive the love so many have for you. #ImConfidentInDemi Demi, I love you.”
Other stars, including Ariana Grande, Ellen DeGeneres and Lily Allen also tweeted their messages of support...
Demi - who has spoken openly about her struggles with alcohol and substance abuse - recently revealed she’d relapsed after six years of sober living in a heartbreaking ballad titled ‘Sober’.
“Momma, I’m so sorry I’m not sober anymore / Daddy, please forgive me for the drinks spilled on the floor,” she sings in the song’s chorus. “To the ones who never left me, we’ve been down this road before.”
Last month she topped the UK singles chart as a guest vocalist on the Clean Bandit single ‘Solo’.