In academic settings around the world, there is a resurgence of interest in using psychedelic substances for the treatment of addictions, posttraumatic stress disorder, depression, anxiety, and other diagnoses. This case series describes the medical consequences of accidental overdoses in three individuals.Case series of information were gathered from interviews, health records, case notes, and collateral reports.The first case report documents significant improvements in mood symptoms, including reductions in mania with psychotic features, following an accidental lysergic acid diethylamide (LSD) overdose, changes that have been sustained for almost 20 years. The second case documents how an accidental overdose of LSD early in the first trimester of pregnancy did not negatively affect the course of the pregnancy or have any obvious teratogenic or other negative developmental effects on the child. The third report indicates that intranasal ingestion of 550 times the normal recreational dosage of LSD was not fatal and had positive effects on pain levels and subsequent morphine withdrawal.There appear to be unpredictable, positive sequelae that ranged from improvements in mental illness symptoms to reduction in physical pain and morphine withdrawal symptoms. Also, an LSD overdose while in early pregnancy did not appear to cause harm to the fetus.