Nish'ta is a green gaseous biological compound. Once inhaled, it infects all body tissue and makes the mind extremely pliable and susceptible to brainwashing. It is similar to, but stronger and more encompassing than, the pheromone organism used by Hathor. It is not effective on a Goa'uld or a Jaffa, but a similar agent may have been used by Apophis to brainwash Rya'c. Seth used nish'ta to brainwash and control the members of his cult, including SG-1. Its effects can be reversed by an electrical shock, but only after it has infected all tissues, a process which takes approximately one hour, otherwise it will regain a stronghold in the body. Once the effects are reversed, the host becomes immune to re-infection.
Cross Reference: Goa'uld Language, Hathor's Breath, Tommy Levinson, Seth
Episode Reference: Seth