Tolerance means a drug has less effect when it is taken repeatedly. For psilocybin it develops fast. Health Canada says “it is possible to become tolerant to the drug’s effects with regular use”, and that this may occur over several days of continued use (Health Canada). CAMH says that with repeated use of hallucinogens the drug can have reduced or no effect, and that sensitivity returns after a period without use (CAMH).
A 2018 review describes tolerance to psilocybin’s psychological and physiological effects as strong (Johnson et al., 2018). A 2022 review says tolerance to psychedelic effects develops rapidly, but reports it does not develop to some bodily effects such as raised heart rate and blood pressure, so the two reviews differ on the body (Schlag et al., 2022).
Reviewers see rapid tolerance as one reason psychedelics are rarely used compulsively, since it “cannot be overcome by dose escalation” (Schlag et al., 2022). Taking more to chase a blunted effect is a route to an overwhelming, unpredictable experience. Much of the human evidence dates from the 1960s, with few participants.
Sources
- Health Canada: psilocybin and psilocin (magic mushrooms)
- CAMH: Hallucinogens
- Johnson et al., 2018, Neuropharmacology: abuse potential of psilocybin (PMC)
- Schlag et al., 2022, Journal of Psychopharmacology: adverse effects of psychedelics (PMC)
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