Question: how bad can hppd get?
Answer: The prevalence of HPPD was unknown as of 2018. Estimates in the 1960s and 1970s were around 1 in 20 for intermittent HPPD among regular users of hallucinogens. It is not clear how common chronic HPPD may be, but one estimate in the 1990s was that 1 in 50,000 regular users might have chronic hallucinations.