Drug checking for psilocybin mushrooms — what's actually worth doing?

Fentanyl in actual psilocybin mushrooms is essentially unheard of — there's no economic incentive to add it and mushroom texture makes adulteration obvious. The real use case for testing mushrooms is: (1) verifying species identity if you foraged, (2) testing pills or powders sold as synthetic psilocybin, (3) NBOMe compound testing if you have something that claims to be LSD. Fentanyl strips are cheap and worth running on any pill or powder regardless.

For species identification when foraging: a Ehrlich reagent test (turns purple-violet positive for indoles, including psilocybin) costs $15 and gives you meaningful confirmation that you have a psilocybin-containing species. Not definitive for identity — several non-cubensis species also test positive — but rules out amatoxin-containing lookalikes that don't contain indoles.

For pills/powder labeled as synthetic psilocybin: Ehrlich reagent plus a fentanyl strip. Synthetic psilocybin is legitimately available from some vendors now in legal contexts. If you bought it from an unclear source, verify it. DanceSafe (dancesafe.org) sells testing kits and has mail-in services at some locations.