Laudanol is the name of a government-created new drug, first seen in "Chuck Versus the Tic Tac", which has been designed by the CIA to remove the emotions of whoever takes it. It was originally intended to be given to American soldiers, so that they are able to able to perform better in battles, making them fearless and maybe even removing pain. Chuck asks if the pill would work for him, as it is the presence of this emotional turmoil which is causing the Intersect 2.0 to not function properly.
When Chuck is in Casey's old fiancée, Kathleen McHugh's, house and preparing to fight off a team of James Keller's soldiers, Chuck takes the Laudanol pill and is able to perform much better in fights - even being able to dodge a bullet that's fired at him. The pill has a negative effect on Chuck, seemingly making him not be able to know when to stop, as he has one of Keller's men by the throat, slowly strangling him. The effects of the pill are overcome when Sarah urges Chuck to stop (due to the feelings he has for her).