Riordan Payne holding the green antidote on the left and the red poison on the right during "Chuck Versus the Truth"

During "Chuck Versus the Truth", a toxic Truth Serum (a derivative of Pentothal) is featured, being used by Riordan Payne at the beginning of the episode to extract information from Mason Whitney relating to nuclear missile codes. The poison forces the subject to tell the truth for the first few hours, until it results in death. During the course of the episode, Chuck, Sarah, Casey, Riordan and Ellie are all poisoned with the serum, with Ellie almost dying from its effects.

The serum is red in color, with the antidote being a bright green.