Books about psychedelic substances and psychedelic-assisted therapy and mental health treatment. Drugs include psilocybin, MDMA, LSD, ketamine, DMT, ibogaine, ayahuasca, and other hallucinogenic tryptamine, entactogens, entheogens, and dissociative drugs. Some people advocate for responsible personal use and legalization of these substances. Many of them have also been used by indigenous cultures in a ceremonial context. 

Psychedelic drugs also currently being studied by a range of non-profit organizations, universities, and public and private companies, seeking drug approval and therapeutic protocols for physical and mental health challenges that include depressions, PTSD, adult ADHD, chronic pain, binge eating, alcohol abuse, cluster headaches. and even glaucoma.