The recommended adult single dose of paracetamol is two standard 500 mg tablets. The overdose threshold may be lowered in a person taking certain prescription medicines, or a person who is an alcoholic or is seriously undernourished. If the overdose is spread over a period of time the threshold may be higher, as the initial paracetamol dose is effectively metabolised. There are often no symptoms in the first 24 hours following overdose, although there may be mild nausea and vomiting. In a large overdose liver function deteriorates leading to jaundice, confusion, and loss of consciousness.
Death is rare but when it occurs it is due to liver failure.
Treatment of a serious paracetamol overdose is mainly by administration of an antidote which can prevent the toxic effects of the overdose. This must be done early, ideally within 12 hours of the overdose although it can still be beneficial up to 24 hours or even later. Treatment must be supervised in a hospital. It is important that if a paracetamol overdose is suspected, hospital treatment is sought without delay. In England and Wales on average approximately 130 deaths per year can be directly attributed to paracetamol alone.