Quite a few precursors to modern stimulants though, there were many Solanaceae (nightshade) variations in Europe, from harmless through high to deadly. Papaver somniferum (opium poppy) got about the place quite a bit (according to archaeologists at least.

Hemlock and henbane were both used as painkillers and dulling agents .. up to unconsciousness and death, depending on dosage.

Added: Monastery herb gardens often had quite the range, eg: https://www.english-heritage.org.uk/visit/inspire-me/blog/ar...