Toxicology & Antidotes

The Poisoned Patient: A Systematic Approach

The instinct in poisoning is to reach first for the name of the drug — to find the antidote, the reversal, the magic bullet. But the patient in front of you rarely arrives with a label, and the poison is almost never the first thing that kills them. What kills them first is a lost airway, a stopped breath, a collapsing circulation — problems you can treat without ever naming the toxin. The whole discipline of toxicology begins with a discipline of restraint: resuscitate the patient, not the poison, and let a structured risk assessment — not a panicked search for an antidote — tell you what happens next.

The Toxidromes: Reading the Poison From the Bedside

A poisoned patient rarely arrives with a label. There is no bottle in the pocket, no reliable history, sometimes no history at all — just a body doing strange things. And yet, long before a single level comes back from the lab, you can often name the culprit. The trick is that most poisons don't act at random: they pull the same few levers — heart rate, pupils, skin, mind, gut — in a recognizable pattern. That pattern is a toxidrome, and reading it is the difference between treating blind and treating the poison.

Gastrointestinal Decontamination: What Works, What's Obsolete

There is a reflex, deep in medical folklore, that says a person who has swallowed poison must be "pumped out." It is one of the most persistent — and most wrong — ideas in emergency care. The truth of gastrointestinal decontamination is far narrower and far more disciplined: it is a small, time-sensitive manoeuvre to stop a poison from being absorbed, useful in a handful of the right patients within a short window, and frankly harmful in the wrong ones. Most of the dramatic old methods have been quietly abandoned. What remains is a single question asked coolly at the bedside: will removing this poison do more good than the removing itself will cost?

Enhanced Elimination and the Logic of Antidotes

Decontamination tries to stop a poison getting in. But what do you do once it is already absorbed — coursing through the blood, distributing into tissue? Two very different tools answer that question. The first is enhanced elimination: clever tricks of chemistry and dialysis that pull the toxin out faster than the body could manage alone. The second is the antidote — a specific molecular counter-move that neutralises the poison or its mechanism. Both are seductive, and both are far rarer than students expect. For the overwhelming majority of poisonings, the treatment that saves the patient is not a magic reversal agent at all, but meticulous supportive care.

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.