There is a drug — probably sitting in your purse, desk drawer or medicine cabinet — that is widely considered one of the world’s safest painkillers. But over the last decade, it has killed hundreds of Canadians, hospitalized tens of thousands and cost the health-care system tens of millions, a Toronto Star investigation has found.

Acetaminophen has spent more than half a century as one of Canada’s top-selling non-prescription drugs. It can be found in nearly 500 products and billions of doses are taken safely every year.

But few Canadians appreciate the potential dangers of acetaminophen — the ingredient that made Tylenol famous but can be found in everything from Nyquil and NeoCitran to prescription painkillers such as Percocet. This is a drug many consumers take as casually as M&Ms — both of which can be bought at any gas station or drugstore, sometimes in packages containing hundreds.

While Health Canada tried to address these issues by updating label warnings in 2009, it ignored stronger changes recommended by its own scientists, according to internal documents obtained by the Star — language that was also opposed by the non-prescription drug industry.

Related: Reports offer insight into acetaminophen overdoses

via The dark side of acetaminophen | Toronto Star.