HPPD is definitely real, but I would describe that as a more or less constant experience of after-effects for weeks&#x2F;months&#x2F;etc.<p>I took enough LSD and other substances to experience HPPD that steadily faded over the course of about 3 months. Once it was over though, I never randomly experienced a small trip or anything.<p>From what I&#x27;ve read that idea comes from a myth that psychedelics build up in parts of the body (e.g. the spine) and can spontaneously be released. So, I wouldn&#x27;t worry about it (and for what it&#x27;s worth -- I&#x27;ll get downvoted to hell for this -- but in the past I drove hundreds of times on psychedelics, without incident)