Psychedelic drugs are seeing a surge of interest from mainstream medicine, and initial results suggest that psychedelic-therapy can be a safe and effective treatment for some mental health conditions. However, the side-effect profile is still incompletely understood. In particular, the use of psychedelics has been posited to carry a risk of triggering latent psychotic disorders or persistent visual hallucinations, known as hallucinogen persisting perception disorder (HPPD).

In order to better understand the prevalence and risk factors of such side-effects, Katie Zhou and colleagues surveyed 654 people online who were planning to take psychedelics through their own initiative. The findings are published in the journal PNAS Nexus.

Of the 654 people surveyed, 315 people were resurveyed two weeks after their experience and 212 people were resurveyed again four weeks after their experience. The sample was 74% male, and 77% university-educated. About one-third had been diagnosed with at least one psychiatric condition.