Yes there is good evidence that acetaminophen (the active ingredient in Tylenol) can deplete glutathione under certain conditions. But whether that matters depends on dose, duration, and individual factors. Silymarin prevents acetaminophen induced hepatotoxicity via up regulation of the glutathione conjugation capacity in mice ScienceDirect Tylenol, Autism, And The Glutathione Connection OC Integrative Medicine Use Only as Directed ProPublica Tylenol And Glutathione Invigor Medical Acetaminophen and NSAID Toxicity Life Extension