Here it is commonly heard, Biogesic, the safest pain reliever. I think that was part of a commercial before, and has stuck in many people's minds. So when is it deadly as you say? Tnx.
Because Paracetamol is, in general, a very safe analgesic (painkiller) and antipyretic (used to treat fever) the mistake is to assume that it is ALWAYS safe.
This, however, is not so.
Individuals that belong to the following categories are most at risk from Paracetamol: alcoholics, the malnourished, extreme old age, patients who cannot eat for an extended period of time (say because of complications after surgery), chronic liver disease, anorexia nervosa, and others as well.
The key theme that connects all of these together is poor nutrition.
Because of the way Paracetamol is metabolised in the liver if an individual has poor nutrition then the liver will produce toxic metabolites that actually kill liver cells. Taken to the extreme this is fatal.
(This is the way people die from Paracetamol overdose - the liver's usual metabolic pathways for Paracetamol are overwhelmed and so the toxic metabolites are produced instead.)
Otherwise healthy people taking Paracetamol as prescribed for only a couple of days will almost never run into trouble.