Analgesic & OTC Poisoning
Paracetamol and N-acetylcysteine, salicylate poisoning, and the anticholinergic overdose.
Paracetamol Poisoning: NAPQI and the N-Acetylcysteine Rescue
Paracetamol is the safest drug in the medicine cabinet — until it isn't. At the right dose it is so gentle it is given to newborns and pregnant women; in overdose it is the commonest cause of acute liver failure in the Western world and the drug most often reached for in deliberate self-harm. The cruelty is in the timing: the patient who has taken a fatal amount feels completely well for a day or two, walks and talks normally, and only declares itself when the liver is already dying. The whole discipline of poisoning turns on this single deception — and on an antidote so good that, given in time, it makes the poisoning almost survivable to a certainty.
Salicylate Poisoning: The Mixed Acid–Base Puzzle
Aspirin is the humblest drug in the cabinet — a few pennies a tablet, sold beside the chewing gum. In overdose it becomes one of the most intellectually demanding poisonings in medicine, because it does not attack an organ so much as it hijacks the body's acid–base chemistry. The patient breathes too fast and too deep, their blood turning alkaline at the top and acidic underneath, all at once. Get the chemistry right and you can pull them back with fluid, bicarbonate and a dialysis machine. Miss it — especially the moment the pH tips the wrong way — and a cheap painkiller kills.
Anticholinergic Poisoning: Physostigmine and Its Cautions
It is one of the most common poisonings in any emergency department, and one of the most recognizable — a whole clinical picture you can read off the patient from across the room. A confused, flushed, wide-eyed patient with dry skin and a racing heart is not a mystery; they are advertising a single lesion in the nervous system: the muscarinic acetylcholine receptor has been switched off. The culprit is usually something bought over a pharmacy counter — a sleep aid, an allergy tablet. The management is mostly patience and benzodiazepines. And there is one antidote that reverses the whole syndrome in minutes — and one situation where reaching for it can kill.
