They are decribed as complications from the overdose.
While TMZ reported the overdose was heroin-related, a source close to Lovato told PEOPLE that it was not heroin-related. The doctors overseeing Demi's recovery have not decided when she'll be released from the hospital, but the news isn't all bad.
"Lovatics have chose to put on their own concert today in Atlantic City where Demi Lovato was scheduled to perform before the cancelation to show their support", one Twitter account captioned a moving clip of fans crowding onto the stage together to happily sing Lovato's songs despite her absence. Narcan - an emergency medicine used to reverse the effects of some drug overdoses - was reportedly administered to Lovato.
As Lovato heals, thousands of fans from around the world have sent her love and support from afar.
In June 2017, she released a new song called "Sober", on which she revealed she had relapsed after six years of sobriety.
TMZ - the site that broke the story of Lovato's apparent overdose on Tuesday last week - reported that the singer is "very, very sick". She's now on Day 6. "Demi's team has been down this path with her before and, although hesitant at first, she agreed to go to rehab".
The "Tell Me You Love Me" singer has been open about her addiction troubles in the past, talking about her life battles in Simply Complicated. "She will be leaving the hospital and heading straight to rehab". While Lovato's hard-partying pals want to be allowed access to the singer, her family wants to put the lid on that and limit visitors to just family and Demi's ex, Wilmer Valderrama.