Demi Lovato. Photo: John Salangsangn/AP

Demi Lovato allegedly "smoked Oxycodone possibly laced with fentanyl" before she was found collapsed at her home in Los Angeles at the end of last month. 

The 25-year-old singer is currently in rehab following a suspected overdose three weeks ago but, although details on the incident are being tightly guarded, it's been claimed that she had inhaled a painkiller combined with the depressant drug - the same medication that killed Prince - and that led to her falling unconscious. 

According to TMZ, Demi allegedly contacted a drug dealer via text message in the early hours of July 24 and asked him to join her at her home in Hollywood Hills. 

The pair then allegedly smoked Oxycodone "on tin foil" but the 'Sorry Not Sorry' hitmaker was completely unaware that it may have been laced with fentanyl as the dealer had a "bad habit of buying [tainted] drugs from Mexico."

The dealer - who the singer had reportedly been seeing since April - stayed overnight but allegedly fled the scene when he noticed that Demi was breathing heavily in bed and it wasn't until 11:30 the next morning that her staff found her unconscious. 

Paramedics were called to Demi's home immediately and Narcan - a medication used to block the effects of opioids, especially in overdose - was administered. 

She was then rushed to hospital and spent two weeks there recovering, during which time she suffered severe complications, before she checked herself into rehab. 

Upon being discharged from hospital, Demi told her fans: "I have always been transparent about my journey with addiction. What I've learned is that this illness is not something that disappears or fades with time. 

"It is something I must continue to overcome and have not done yet. I want to thank God for keeping me alive and well. To my fans, I am forever grateful for all of your love and support throughout this past week and beyond. 

"Your positive thoughts and prayers have helped me navigate through this difficult time. I now need time to heal and focus on my sobriety and road to recovery. 

"The love you have all shown will never be forgotten and I look forward to the day where I can say I came out on the other side. I will keep fighting." 

Demi - who has battled with drugs and alcohol abuse in the past - had stayed away from substances for six years but she recently revealed that she had fallen off the wagon when she released her song 'Sober' in June.