Pop superstar Demi Lovato was rushed to the emergency room in L.A. after reportedly overdosing on heroin. Sources told TMZ that the singer was transported to a medical facility and is currently receiving treatment. In 2011, Lovato entered a facility and was treated for bipolar disorder, bulimia and as self-harm. Last month she dropped a new song titled ?Sober? where she revealed that she?d fallen off the wagon. In the song she promises her fans and family that she'll "fight on," reports Uproxx.