Therapeutic claims about many psychedelic drugs have not been evaluated in any studies of even modest rigor. The science of psychedelic drugs is strengthening, however, making it easier to differentiate some promising findings amid the hype that suffuses this research area. Ketamine has risks of adverse side effects (e.g., addiction and cystitis), but multiple studies suggest it can benefit individuals with treatment-resistant depression. Other therapeutic signals from psychedelic drug research that merit rigorous replication studies include 3,4-Methylenedioxymethamphetamine (MDMA) for post-traumatic stress disorder (PTSD) and psilocybin for depression, end of life dysphoria, and alcohol use disorder. The precise mechanisms through which psychedelic drugs can produce benefit and harm are not fully understood. Rigorous research is the best path forward for evaluating the therapeutic potential and mechanisms of psychedelic drugs. Policies governing the clinical use of these drugs should be informed by evidence and prioritize the protection of public health over the profit motive.