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. Glutathione and MTHFR Methyl Life Supplements Is Tylenol Safe During Pregnancy? Understanding Risk Factors Seeking Health Silymarin prevents acetaminophen induced hepatotoxicity via up regulation of the glutathione conjugation capacity in mice ScienceDirect