According to HollywoodLife, Sel has been "hit hard" by Demi's relapse.
“Selena [Gomez] has been struggling with Demi [Lovato]’s condition and her extended stay in the hospital. It has really hit Selena hard. She has been thinking about Demi a lot and Selena finds herself fighting back the tears worrying about her,” the source said.
“Selena feels horrible that Demi is going through this challenging time and it scares her to think that her friend could be in so much pain. Selena has battled her own health issues over the years, so she knows how terrible it can be feeling stuck in the hospital. Selena wishes there was more she could do to help Demi. She feels helpless and is genuinely concerned for Demi. She is praying Demi will make a recovery."
Demi is currently recovering in hospital following her overdose last Thursday.
A rep for the singer spoke out about her condition following the ordeal.
"Demi is awake and with her family who want to express thanks to everyone for the love, prayers and support," Nicole Perna said in a statement to USA TODAY.
"Some of the information being reported is incorrect and they respectfully ask for privacy and not speculation as her health and recovery is the most important thing right now."
According to TMZ, the singer suffered some "complications" in hospital, including "extreme nausea and a high fever" throughout her time in the hospital.
Demi has battled addiction, mental illness and an eating disorder for years. In 2011, the entertainer entered rehab, where she was also treated for bipolar disorder, bulimia, self-harm and addiction.