While most people are fine after taking psychedelics, some people experience lasting visuals after a trip: https://en.wikipedia.org/wiki/Hallucinogen_persisting

While most people are fine after taking psychedelics, some people experience lasting visuals after a trip: https://en.wikipedia.org/wiki/Hallucinogen_persisting_perception_disorder https://en.wikipedia.org/wiki/Hallucinogen_persisting_percep... There are some interesting videos on YouTube from people experiencing this.