Impact Canada, a Government of Canada site, defines drug checking as a harm reduction measure in which people have their illegal drugs tested to find out what is in them, including toxic contaminants or unexpected and potent substances like fentanyl (Impact Canada). Health Canada lists drug checking at supervised consumption sites among its harm reduction examples (Health Canada).
Canadian data show why it exists. A student-run service at a Canadian university tested 121 samples between September 2021 and April 2024, and 38 of them (31.4%) did not match what the person expected (Airth et al., 2025). Nearly half of the samples were expected to be psychedelics, but the study gives no separate mismatch figure for them.
The mushroom market shows the same problem. A 2025 study of 12 psilocybin edibles found no psilocybin in any of them, along with undisclosed caffeine, kava, cannabinoids and synthetic tryptamines (van Breemen et al., 2025). A check covers only the sample tested; it says nothing certain about another piece or batch.
General information, not medical advice. In an emergency in Canada, call 911. For a mental-health crisis, call or text 9-8-8.
Sources
- Impact Canada: What is drug checking?
- Health Canada: Substance use services and supports
- Airth et al. (2025), A campus-based drug checking service at a Canadian university
- van Breemen et al. (2025), Active constituents of psilocybin mushroom edibles
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