Tylenol (Acetaminophen) poisoning happens when someone takes more than the suggested dose. The recommended dose is 4000 mg daily. While considered safe in medicinal doses, at larger doses, acetaminophen can be fatal. Nearly half of all cases of acute liver failure in the United States and England can be attributed to acetaminophen poisoning.
Symptoms of acetaminophen poisoning may not present until 12 or more hours after the acetaminophen was ingested. Without early treatment, within the first 8 hours after the overdose, acetaminophen poisoning may lead to liver failure and death within 3 to 5 days.
Once the acetaminophen is ingested, a complex sequence of events begins which ultimately leads to liver failure. In the second step of this process the glutathione levels in the liver are completely depleted which allows for the formation of oxidative stress among other things.
Studies show that early treatment with GSH and its precursor N-acetylcysteine (NAC) can protect patients with acetaminophen poisoning against the overdose by raising the liver’s mitochondrial levels of GSH and providing support to the energy metabolism of the mitochondria.
http://www.nlm.nih.gov/medlineplus/ency/article/002598.html