What is HPPD (hallucinogenic persisting perception disorder)?
Hallucinogen persisting perception disorder (HPPD) is a chronic (and often permanent) condition where a person feels or sees what they felt or saw during a psychedelic trip. Often it causes problems with vision and sound perception. HPPD is only caused by the prior use of hallucinogens.
There are two types of HPPD:
Type 1 HPPD This is where people experience HPPD in the form of random, brief flashbacks.
Type 2 HPPD People with this kind of HPPD experience ongoing changes to their vision, which may vary in intensity.