Strictly speaking, it doesn't damage the liver by soaking up the supply of glutathione, it's what happens when the glutathione is soaked up and you've still got NAPQI that kills you. For those who care: normal paracetmaol metabolism is largely by glucoronidation or sulphonation, but these pathways can only take so much and the CYP450s take up the slack if they're overloaded (and stil do a bit even if they're not). This pathway transforms the paracetamol into NAPQI, which is usually metabolised by glutathione (or N-acetyl cysteine) conjugation When the glutathione is used up, there's nothing to take out the NAPQI and it reacts with proteins and nucleic acids. Then you get liver failure and a slow and painful death as your liver melts (well, it doesn't literally melt, but it's a pretty good way of describing it)