Psilocybin at 3 mg/kg and Psilocybe cubensis extract matched to 3 mg/kg psilocybin/psilocin shifted gut microbiota structure in 18 male Wistar Han rats over 14 days. Both treatments separated from baseline and control microbiota by day 7, with stronger divergence by day 14 and the largest shift in the pure psilocybin group. This adds a gut-brain-axis layer to psychedelic research, showing that pure psilocybin and whole mushroom extracts can reshape microbial communities differently.