overdose

An overdose is what happens when the amount of a drug taken pushes past the safe range and tips into harm. If a therapeutic dose is the sweet spot on a dial, an overdose is turning the dial too far — the same machinery that helps now runs to excess and starts causing damage.

Overdoses can be accidental (a child finding pills, a confused elderly patient double-dosing, a miscalculation in a hospital) or intentional (self-harm). The clinical picture is usually an exaggeration of the drug's known pharmacology: an opioid overdose suppresses breathing because opioids depress the brainstem respiratory centre; a benzodiazepine overdose causes deep sedation; an excess of a blood-pressure drug causes dangerous hypotension.

Management rests on a few pillars: supporting vital functions (airway, breathing, circulation), limiting further absorption where appropriate (such as activated charcoal soon after ingestion), enhancing elimination in selected poisons, and giving a specific antidote when one exists — naloxone for opioids, N-acetylcysteine for paracetamol, flumazenil for benzodiazepines.

The danger of an overdose depends heavily on the drug's therapeutic index. Drugs with a wide margin tolerate large excesses, whereas drugs with a narrow margin, such as digoxin, lithium, or warfarin, can become life-threatening with only modest excess, which is why they are dosed and monitored so carefully.