When psychedelics leave a mark: HPPD, bad trips and spiritual narcissism
October 7, 2026 · 14 min read
Johns Hopkins researcher Matthew Johnson says the lasting harms of psychedelics are real but uncommon and concentrated in unscreened, unsupervised use, and Andrew Callaghan, who has lived with HPPD since one mushroom trip in eighth grade, shows what the rare case costs. Rick Strassman and Andrew Huberman add risks of a different kind, inflated egos and deaths at clinics, while Post Malone's lasting bad reaction came from cannabis and he credits mushrooms with lifting his depression.
The rules, numbers and steps worth keeping in front of you.
- Johnson's two big risks are destabilizing people prone to psychosis or mania, and bad trips that turn deadly outside a safe setting.
- Johnson's trials exclude people with psychotic or bipolar disorders and those with close relatives who have them.
- At about 30 mg of psilocybin, roughly a third of Johnson's lab participants feel strong fear at some point.
- Johnson says to surrender to the experience rather than fight it.
- Johnson calls HPPD real but rare and says it has never been seen in thousands of research participants. It has also been reported after alcohol, cannabis, benzodiazepines and tobacco.
- Callaghan's lifelong HPPD began with one normal dose of mushrooms in eighth grade. There is no formal research in people under 18.
- Callaghan's grounding rule is that the distortion is only visual and his other senses say he is here. Do not copy his early drinking.
- Johnson warns that serotonin 2B receptor activity raises heart valve concerns with frequent dosing over years. Microdosing studies show no benefit or slight impairment so far.
- Johnson advises no big life decisions for a couple of weeks after a session.
- Strassman says psychedelics amplify existing traits. An urge to instruct others is a warning sign.
- Huberman says to ask clinics about therapist conduct and, for ibogaine, about deaths and prior fentanyl use.
- Johnson says to search clinicaltrials.gov for approved studies.
- Talk to a doctor before using psychedelics for mental health. See a physician for lasting visual changes or unreality, and do not self-treat with alcohol.
This is the short form. The full insight has every expert's reasoning, their own words and the sources.