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. Why you should avoid REGULAR acetaminophen use for babies and pregnancy 3 Little Plums Electrochemical evidences in oxidation of acetaminophen in the presence of glutathione and N acetylcysteine Chemical Communications (RSC Publishing) Sex differences in glutathione metabolism and acetaminophen toxicity