A poisoning adsorbent
Activated charcoal
An emergency medicine given by mouth to bind some poisons in the gut and reduce how much is absorbed.
What is Activated charcoal?
Activated charcoal is given by mouth soon after some poisonings or overdoses to bind the substance in the gut so that less of it is absorbed into the body. It is a specially treated charcoal with a huge surface that traps many drugs and chemicals. It only helps within a limited time after the poison was taken, and it does not work for all poisons (for example, it does not bind iron, lithium or alcohols). Because there is a risk of it going into the lungs if someone is drowsy or vomits, it is given only when the airway can be kept safe.
Education and reference only. This is a plain-language guide to Activated charcoal — it deliberately contains no doses. Doses depend on the person, the brand and the reason for treatment, and belong with your prescriber. Always check the BNF, the product labelling (SmPC) and follow medical advice.
What it is
Activated charcoal is a fine black powder of charcoal that has been treated to make it extremely porous, giving it an enormous internal surface area. Mixed with water into a drink, it is used in hospital after certain poisonings and overdoses to soak up the harmful substance inside the gut before the body can absorb it. It is an emergency treatment given under professional supervision, not a remedy for everyday upset stomachs or wind.
How it works
Activated charcoal works by adsorption, meaning poisons and drugs stick to its vast surface rather than being taken up into the bloodstream. By trapping the substance in the gut, the charcoal carries it out of the body in the stools instead. This only helps while the poison is still in the stomach and gut, which is why timing matters so much. It cannot remove anything already absorbed, and some substances simply do not stick to it.
Company & origin
Originated / developed by: Generic (long-established).
An emergency treatment used in UK hospitals to reduce absorption of certain poisons and overdoses taken by mouth.
Practical use
How to take Activated charcoal
General, dose-free guidance — always follow your prescriber's and the leaflet's specific instructions.
- It is given as a black drink mixed with water, under supervision in hospital, ideally soon after the poison was taken.
- It is only given when you are awake enough to swallow safely or your airway is otherwise protected.
- Drink it as directed; the team may flavour it or use a straw to make it easier to take.
- Expect your stools to turn black for a few days, which is harmless.
- Other medicines may need to be spaced apart from it, as it can reduce their absorption.
Weighing it up
Advantages & disadvantages of Activated charcoal
Advantages
- Can substantially reduce absorption of many poisons and overdoses if given soon enough.
- Binds a wide range of drugs and chemicals because of its very large surface area.
- A simple, non-invasive treatment given by mouth when used in the right situation.
Disadvantages
- Only works within a limited time after the poison is taken and not for all substances.
- Carries a risk of serious lung damage if breathed in, so the airway must be safe.
- Can cause vomiting, constipation and black stools, and reduces absorption of useful medicines.
Practical use
Good to know
Activated charcoal is most useful when given soon after a poison is swallowed, often within about an hour, though the window can be longer for some slow-release or large overdoses; the decision is made by clinicians or the poisons information service. It does not bind everything: it is not effective for iron, lithium, strong acids or alkalis, or alcohols such as methanol and ethylene glycol. The main safety concern is that if it is breathed into the lungs, for example in someone who is very drowsy or who vomits, it can cause serious lung damage, so it is only given when the airway is protected. It turns the stools black, which is expected and harmless, and it can cause constipation or vomiting. It can also reduce the absorption of helpful medicines, so other drugs may need to be separated from it.
Who should not take it / use with caution
- People who are too drowsy to protect their airway, unless it is protected by the team, because of the risk of it entering the lungs.
- It is not used for poisons it does not bind, such as iron, lithium, alcohols, or strong acids and alkalis.
- People with a blocked or non-working bowel, where it could cause harm.
Monitoring
- Checking the person is awake enough to swallow safely and the airway is protected before giving it.
- Watching for vomiting, which raises the risk of it entering the lungs.
- Monitoring the person's condition and, for some poisons, blood levels and repeat dosing decisions.
Side effects
- Black stools, which are expected and harmless.
- Nausea, vomiting and constipation.
- Rarely, serious lung damage if it is breathed into the lungs, or bowel blockage with repeated doses.
Key interactions
- Reduces the absorption of many medicines taken by mouth, so other drugs may need to be separated from it.
- Does not bind certain poisons, including iron, lithium and alcohols, so it is not used for these.
- Repeated doses are sometimes used for particular poisons, guided by the poisons information service.
Available as: Powder or pre-mixed liquid taken by mouth as a drink, given under supervision.
Answers
Activated charcoal: frequently asked questions
What is activated charcoal used for?
In emergency care it is given by mouth soon after some poisonings or overdoses to bind the substance in the gut and reduce how much the body absorbs.
Does it work for every poison?
No. It binds many drugs and chemicals but not all; for example, it does not work for iron, lithium, alcohols, or strong acids and alkalis.
Why does the timing matter?
It can only trap a poison still in the gut, so it is most useful soon after the substance is swallowed and cannot remove anything already absorbed.
Is it dangerous?
Its main risk is going into the lungs if someone is very drowsy or vomits, which can cause serious lung damage, so it is only given when the airway is safe.
Why have my stools turned black?
Activated charcoal normally turns the stools black for a few days, which is expected and harmless.
Authoritative sources
- BNF
- NICE CKS
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