The poisoned patient: a case-based approach

The case: an uncertain overdose

Imagine Tom, a young man brought to the emergency department by a friend who found empty medicine packets beside him. He is drowsy but rousable, a little confused, and unsure how much he has taken or when. He mentions taking paracetamol and drinking alcohol several hours earlier. He feels nauseous but has no pain yet. Scenarios like this are common and challenging: the history is often unclear, more than one substance may be involved, and the person may feel completely well early on even after a serious overdose. This is why every suspected overdose is treated seriously and assessed urgently, regardless of how the person looks at first.

First priorities: supportive care

The first job in any poisoning is not the antidote but the patient. Clinicians follow an Airway, Breathing, Circulation, Disability and Exposure approach, treating what they find. That means protecting the airway if consciousness is reduced, supporting breathing and oxygen, checking heart rate, rhythm and blood pressure, and measuring blood glucose and temperature. Good supportive care alone saves most poisoned patients, because it keeps the body stable while the substance is cleared naturally. The team also looks for clues — tablet packets, a pattern of symptoms, or a distinctive combination of signs — that point to what was taken. Throughout, staff stay alert to the person's safety and mental state.

Finding out what was taken

A careful history is central: what substance, how much, when, by what route, and whether alcohol or other drugs were involved. Collateral information from friends, family, ambulance crews or GP records is invaluable, as patients may not know or may under-report. Timing matters enormously, because some treatments and blood tests are only meaningful at set intervals after ingestion — paracetamol levels, for example, are interpreted against the time since the overdose. Basic tests often include blood gases, kidney and liver function, and specific drug levels where relevant. UK clinicians routinely consult TOXBASE, the National Poisons Information Service database, and can telephone its specialists for advice on unusual or severe cases.

Specific treatments and antidotes

Only some poisons have a specific antidote, and these are guided by expert advice rather than guesswork. Paracetamol overdose, one of the most common in the UK, has an effective antidote that works best when started early — which is why prompt attendance matters even when someone feels well. Other examples include antidotes for certain opioid, iron or specific medication overdoses. Decontamination, such as activated charcoal, is only used in particular situations and time windows. Some poisons can be removed faster by techniques such as dialysis. The key principle is that treatment is tailored to the substance, the amount and the timing, using national toxicology resources rather than assumptions.

Safety, aftercare and prevention

Poisoning is not only a physical emergency. Where an overdose may have been intentional, a compassionate mental health assessment is an essential part of care once the person is medically stable, and support and follow-up are arranged. For accidental poisonings — common in young children with household products or medicines — prevention advice matters: keep medicines and chemicals locked away, in original containers, and out of reach. Everyone can help by never delaying: even substances that seem harmless, or amounts that seem small, can be dangerous, and early treatment is far more effective. If poisoning is suspected, contact 999 or NHS 111 immediately, and keep any packaging to help the clinical team.