The drug psycho has appeared in all of the Fallout games. It consists of a syringe, a vial of the drug, a small tube and a large band to hold it together. It's a pretty 'rag-tag' medicine that gives the user a short 25% increase in damage output.
Psycho is used as a stimulant by NPCs; the effects would probably increase one's heart rate and make the user resistant to pain. You can become addicted to Psycho, which entails the need to continue using it, otherwise suffer the side effects of withdrawal which cause the player to have less Endurance and Perception