Psilocybin mushroom use has sharply increased in the US, particularly among adults aged 19 to 50 years, with more than 7 million individuals reporting use in the past year. This trend has coincided with a substantial increase in poison control center calls related to psychedelics. Testing data from decriminalized regions indicate more than 20-fold variability in psilocybin potency and inconsistent levels of minor tryptamines across mushroom strains. Clinical trial data on synthetic psilocybin do not generalize to public use due to strict participant selection and controlled environments. Co-use with cannabis is common and may increase the risk of adverse events. The expanding use of unregulated psilocybin mushrooms, combined with high variability in composition and common co-use with other substances, raises urgent public health concerns.
Among attendees of festivals and concerts in Colorado, simultaneous use of cannabis and psychedelics is common, with many users reporting enhanced positive experiences such as deeper introspection and sensory amplification. However, a notable minority experience adverse reactions including anxiety, paranoia, and confusion. Qualitative interviews reveal that users often intentionally combine substances to modulate the psychedelic experience, but the lack of predictable outcomes and setting-related factors contribute to negative effects. The findings suggest that simultaneous use carries both potential benefits and risks that are influenced by dose, individual tolerance, and environmental context.