Appearance
23.6 — Poisoning and Overdose
Do not make them vomit.
This is the first line of the chapter because it is the instruction most often ignored, and because it causes harm every time. Syrup of ipecac was standard household advice for decades. It was withdrawn because studies showed it did not improve outcomes and did cause harm — aspiration into the lungs, and delay in giving treatments that work.
Salt water is worse. Forced salt water ingestion has killed children through sodium poisoning.
And for corrosive substances, vomiting takes the acid or alkali back up through the oesophagus a second time, doubling the burn.
So: no vomiting, no salt water, no milk as a universal antidote, and no home remedies.
What you do instead is on this page.
The immediate steps
1. Make yourself safe.
For gases, fumes and chemicals, do not enter. Carbon monoxide, hydrogen sulphide and other gases have killed rescuers reliably, and hydrogen sulphide in particular deadens the sense of smell so the warning disappears.
A collapsed person in a confined space is a trap (Chapter 23.1).
For chemicals on the skin, wear gloves and avoid contact.
2. Remove them from the source, if you can do it safely.
Fresh air for gases.
3. Check response, airway and breathing (Chapter 23.1).
If unresponsive but breathing: recovery position, which matters enormously here because vomiting is very common in poisoning.
If not breathing normally: CPR. Use a face shield or do compression-only CPR if there is any chance of a chemical around the mouth.
4. Call for help.
An ambulance for anyone unwell, drowsy, or who has taken a significant amount.
And call a poisons information service. Most countries have one, staffed around the clock, and they are extraordinarily useful. They will tell you exactly what a specific product does and what needs to happen.
5. Gather information — this is where you add the most value.
What was taken. Bring the container, the packet, the blister strip, the plant, the mushroom, the bottle.
How much — count the tablets remaining against what the pack should hold.
When — the exact time, which determines whether treatments still work.
By what route — swallowed, inhaled, absorbed, injected.
And whether alcohol or anything else was taken too, which is very common and changes the treatment.
6. Do not leave them alone.
Even someone who seems well. Many poisons have a delay before effects appear, and the reason is different for each — some need to be metabolised into a toxic product, some are slowly absorbed, some damage organs silently.
What never to do
Do not induce vomiting.
Do not give salt water, mustard water or anything else to induce vomiting.
Do not give anything to eat or drink unless the poisons service specifically says so.
Do not give milk automatically — it is not a universal antidote, and it can speed absorption of some substances.
Do not use activated charcoal at home, despite what the internet says. It has a role, given by professionals within about an hour, and given wrongly it can be aspirated into the lungs with severe consequences.
Do not try to neutralise an acid with an alkali or vice versa — the reaction generates heat and makes the burn worse.
Do not assume that because someone looks fine, they are.
The specific poisonings worth knowing
Paracetamol
The most important overdose in this chapter, because it is common, initially silent, and completely treatable if caught in time (Chapter 22.5).
The mechanism: normal metabolism produces a small amount of a toxic product called NAPQI, which glutathione neutralises. In overdose, glutathione is exhausted and NAPQI destroys liver cells.
The timeline is what makes it dangerous:
0 to 24 hours: nothing, or mild nausea. The person feels fine.
24 to 72 hours: right upper abdominal pain, and blood tests showing liver damage beginning.
72 to 96 hours: liver failure — jaundice, confusion, bleeding, and kidney failure.
Which means the window in which treatment is nearly perfect closes before the person feels ill at all.
Treatment: acetylcysteine, which replenishes glutathione.
Close to 100 percent effective if started within 8 hours. Progressively less effective after that, and still worth giving well beyond 24 hours.
So: go to hospital immediately after any paracetamol overdose, regardless of how well the person feels, and regardless of how small it seems.
And staggered overdoses count — repeated doses slightly above the maximum over hours or days, which is a common pattern in someone treating pain, and is treated seriously.
Higher risk in: chronic alcohol use, malnutrition, eating disorders, low body weight, and people on enzyme-inducing drugs.
Opioids
Heroin, methadone, morphine, oxycodone, fentanyl, tramadol, codeine.
Death is from respiratory depression — the brainstem's drive to breathe is suppressed and breathing slows and stops (Chapter 11.7).
The triad: unresponsive; very slow or absent breathing; pinpoint pupils.
Also: blue lips and fingertips, snoring or gurgling breathing, and limpness.
Naloxone reverses it, and it deserves the emphasis:
It displaces opioids from their receptors and works within 2 to 5 minutes.
It is available as a nasal spray and as an injection.
It is safe. It cannot harm someone who has not taken opioids. If you are wrong, nothing happens.
Give it. Then call an ambulance and start rescue breaths or CPR.
Two things to know afterwards:
Naloxone wears off in 30 to 90 minutes, and many opioids last far longer. The person can go back into overdose after appearing to recover. They must go to hospital, and they must not be left alone.
And reversal precipitates immediate withdrawal in a dependent person — vomiting, agitation, distress. That is unpleasant and not dangerous, and it is not a reason to withhold naloxone. The dose can be titrated to restore breathing without full reversal where the person is trained.
Fentanyl and its analogues are potent enough that a very small quantity is lethal, and multiple naloxone doses are frequently needed.
And the highest-risk moment: after a period of abstinence. Tolerance falls within days, and deaths cluster after release from prison and after completing detox (Chapter 20.10).
Take-home naloxone belongs in any household where opioids are present, prescribed or otherwise.
Carbon monoxide
Colourless, odourless, and it kills whole families.
From faulty boilers, blocked flues, gas heaters, charcoal barbecues brought indoors or into tents, generators, and car exhausts.
It binds haemoglobin around 240 times more tightly than oxygen does, so the blood cannot carry oxygen even though breathing looks normal (Chapter 8.4).
Symptoms: headache — the commonest and earliest; dizziness; nausea; confusion; weakness; and breathlessness.
They mimic flu or food poisoning exactly, which is why it is missed.
The clues that distinguish it:
Several people or pets in the same building unwell at the same time.Symptoms that improve when away from the building and return on going back.Symptoms worse in winter, when heating is on.And a boiler flame burning yellow or orange rather than blue, or sooty staining around an appliance.
The classic "cherry red skin" is a late and unreliable sign, mostly seen after death. Do not wait for it.
What to do: get everyone out into fresh air immediately, open doors and windows, turn off the appliance if you can do it safely, and call emergency services.
Treatment is 100 percent oxygen, which reduces the half-life of carbon monoxide from around 5 hours in room air to about 1 hour. Hyperbaric oxygen is used in severe cases.
And prevention is a carbon monoxide alarm. They cost very little, they are as important as a smoke alarm, and far fewer homes have one.
Corrosives — acids, alkalis, bleach, drain cleaner, oven cleaner
Do not induce vomiting. Do not neutralise.
Skin or eyes: irrigate with copious running water immediately, for at least 20 minutes — and longer, up to an hour, for alkalis, which penetrate deeper and keep burning.
Remove contaminated clothing while irrigating.
Eyes: hold the lids open and irrigate from the inner corner outwards. Continue on the way to hospital if you can.
Swallowed: do not induce vomiting, give small sips of water only if the poisons service advises, and go to hospital.
Alkalis cause deeper injury than acids, because they dissolve tissue progressively rather than forming a coagulated barrier.
Petroleum products — petrol, paraffin, lamp oil, white spirit
Do not induce vomiting, and this is the strongest of all the never-vomit cases.
These liquids have very low surface tension, so on vomiting they spread across the lungs and cause a severe chemical pneumonitis that is far more dangerous than the swallowed dose.
Give nothing by mouth, and get help.
Alcohol
Ethanol poisoning kills, and it is not taken seriously often enough.
Signs of dangerous intoxication: unresponsive or only responding to pain; slow or irregular breathing; cold, clammy, pale or blue skin; repeated vomiting; seizures; and low body temperature.
The dangers: aspiration of vomit, which is the commonest cause of death; respiratory depression; hypothermia; and hypoglycaemia, particularly in children and in malnourished adults.
What to do: recovery position, keep warm, monitor breathing continuously, and never leave them to sleep it off alone.
"Sleeping it off" alone in the recovery position is exactly the situation in which people die of aspiration.
Methanol and ethylene glycol — in antifreeze, screen wash and illicit spirits. They are metabolised into toxic acids, causing blindness, kidney failure and death. The treatment is fomepizole or ethanol, which block the enzyme that produces the toxic product. Symptoms are delayed, so early hospital assessment is essential even when the person seems fine.
Recreational drugs
Stimulants — cocaine, amphetamine, MDMA: agitation, high temperature, chest pain, seizures, and dangerously high body temperature. Cool them, keep them calm, and get help. Chest pain after cocaine is treated as cardiac.
And MDMA specifically carries a risk of dangerous water intoxication — people drink large volumes, and the drug also causes water retention, producing low sodium, seizures and death. The advice is a moderate amount of fluid, not as much as possible.
Depressants — GHB, benzodiazepines: deep unconsciousness, then sometimes sudden waking. Recovery position and monitoring.
And the danger of combinations, particularly with alcohol.
Do not be afraid to say what was taken when you call for help. Emergency services are there to treat, not to prosecute, and withholding it costs lives.
Plants and mushrooms
Take a sample or a photograph of the plant or fungus.
Death cap mushroom poisoning is the classic trap: symptoms begin 6 to 24 hours after eating, then settle for a day, and then liver failure develops. The apparent recovery is what convinces people not to seek help.
Never eat foraged mushrooms without expert identification.
Common garden dangers: foxglove, yew, laburnum, deadly nightshade, oleander, and castor bean seeds.
Iron and children
Iron tablets look like sweets and are a leading cause of serious poisoning in small children.
Even a modest number of adult iron tablets can be lethal to a toddler.
There is a deceptive quiet phase after initial vomiting, before shock and liver failure. Any suspected iron ingestion in a child needs immediate hospital assessment.
Button batteries
And this deserves its own place, because it is fast, hidden and devastating.
A swallowed lithium button battery lodged in the oesophagus generates a current that causes an alkaline burn through the wall — beginning within 2 hours and capable of causing fatal bleeding within days.
Symptoms are non-specific: drooling, refusing food, coughing, chest pain, vomiting. Frequently the swallowing is not witnessed.
This is an immediate emergency. Go straight to an emergency department and say "button battery".
Honey may be given on the way in children over 12 months, 10 ml every 10 minutes, because it coats the battery and slows the alkaline injury — this is a recommended interim measure and it does not replace immediate hospital transfer.
Do not induce vomiting, and give nothing else.
Prevention: keep devices with accessible battery compartments away from small children, and be aware they are in remote controls, car keys, toys, greeting cards and hearing aids.
Antidotes worth knowing
| Poison | Antidote |
|---|---|
| Paracetamol | Acetylcysteine |
| Opioids | Naloxone |
| Benzodiazepines | Flumazenil (used cautiously) |
| Carbon monoxide | High-flow oxygen |
| Organophosphates | Atropine, pralidoxime |
| Iron | Desferrioxamine |
| Methanol, ethylene glycol | Fomepizole or ethanol |
| Warfarin | Vitamin K, clotting factors |
| Beta blockers | Glucagon, high-dose insulin |
| Digoxin | Digoxin-specific antibodies |
| Cyanide | Hydroxocobalamin |
Most poisonings have no specific antidote and are treated supportively — maintaining the airway, breathing and circulation while the body clears the substance.
When it is deliberate
Treat the physical emergency first, always.
Then ensure a mental health assessment happens. Everyone presenting with self-poisoning should be assessed, and this is a standard of care rather than an optional extra.
Do not leave the person alone.
Do not express anger, and do not minimise it either. Both make disclosure less likely.
And remove access to means — medication, and anything else in reach. This is the single most effective practical action, because suicidal crises are frequently short-lived and survival of one is followed by long-term survival in the large majority (Chapter 20.7).
Take every act seriously regardless of the quantity taken. The amount is a poor guide to intent, and people frequently misjudge what is dangerous — someone may take a small overdose believing it will kill them, or a lethal one believing it will not.
Prevention at home
Store medicines and chemicals high, locked, and in original containers.
Never decant chemicals into drinks bottles. This causes serious poisoning every year, and it is entirely avoidable.
Child-resistant caps are resistant, not proof — many three-year-olds can open them.
Handbags on the floor are a very common source of childhood medicine poisoning.
A carbon monoxide alarm on every level of the home.
Dispose of unused medicines at a pharmacy.
And keep the number of your national poisons service saved in your phone.
What the next page fixes
Chapter 23.7 covers burns and electrical injury — how to cool a burn properly, how long for, and the specific hazards that make electrical injury different from every other burn.