Yes they can! We have had customers who take SSRI or SNRI antidepressants experience little to no effects, as they can negate the effects of the psilocybin. This can happen even if you stopped taking your medication recently. If you take focus medication like Adderall or Concerta, there have been reports of anxiousness as well. If you have used or use medications like this, we would advise to try a sample pack first to ensure effects are desirable!