During the congressional hearings he made not one mention of not taking the meds. Not exactly full disclosure one would expect in front of the governing body of the United States.

Mr. Limbaugh was not accusing Mr. Fox of faking the disease, he was accusing him of exaggerating the effects (sort of like testifying in front of Congress without telling them he didn't take meds). He said nothing publicly about that until an interview with Diane Sawyer in 2001 when he admitted he had done so "As an actor". In other words he thought it would be good for effect to not take the meds, he thought it would be good to be "uncomfortable" in front of Congress.

Full transcripts of both Mr. Limbaugh's original comments and the vid clip of Mr. Fox's interview on 20/20 in 2001 are on Mr. Limbaugh's web site.