Kash'ta is a chemical that causes those that inhale it to become enraged and attack only those who had been formerly considered allies and friends prior to being affected. While in the enraged state, they temporarily become stronger and hardier due to the chemical causing an adrenaline surge in the bloodstream.
Kash'ta is favored by the Goa'uld, though it is sufficiently rare enough that even some System Lords are unaware of its properties. The goa'uld use kash'ta when they want to throw their enemies into disarray so they can provide openings for their own attacks or to flee. (RPG: "Fantastic Frontiers: Stargate Season One")