The biosynthesis of prostaglandins proceeds in the presence of fatty acid cycloxygenases (COX-1, COX-2). COX-1 is responsible for the synthesis of prostaglandins indispensable for normal homeostasis, while COX-2 regulates local expression of pro-inflammatory prostaglandins. Paracetamol is a selective inhibitor of COX-2 thus having an analgesic and antipyretic potential. The drug is metabolised primarily in the liver. About 5% of the dose transforms into N-acetylo-p-benzoquinoneimine (NAPQI), a highly active compound. Ingestion of a single paracetamol dose higher than 8 g leads to a depletion of hepatic glutathione reserves and a loss of the detoxifying property of the liver. As a result, hepatic necrosis develops. The specific antidote is N-acetylcysteine (NAC). If applied within 10-15 h since the poisoning it enables complete survival. The efficacy of specific treatment decreases after 24 h but blood paracetamol is an indication for NAC therapy. The surviving patients with advanced paracetamol poisoning require long-lasting conservative treatment with ornithine and phospholipids as well as a light diet.