Aspirin overdose and salicylate toxicity: what to do if too much has been taken

Salicylates are a group of chemicals. The NHS describes aspirin as a non-steroidal anti-inflammatory drug (NSAID) used at a low regular dose to prevent blood clots and at a higher dose, only when needed, to ease pain. The NHS Reye's syndrome page names salicylates, particularly aspirin, as a type of medicine, and warns that children under 16 should not be given medicines containing salicylic acid or salicylate, which includes some mouth ulcer gels.

Salicylate toxicity means that the body has taken in more salicylate than it can safely cope with. The most common source is aspirin tablets, taken by accident, at too high a dose for pain, or on purpose. The sources used for this page do not give blood levels or the detailed way the body is affected, which belong in clinical references, so this guide concentrates on what an ordinary reader needs to know about when to seek help.

The NHS lists medicines among the common causes of poisoning, and gives the examples of paracetamol, ibuprofen and antidepressants. Aspirin is not named in that list, but the same advice applies to any medicine taken in excess.

The NHS sets out how aspirin should be taken. For pain relief, it usually comes as 300mg tablets, of which you take 1 to 3 at a time, ideally with or after food, wait at least 4 hours between doses and take no more than 4 doses in a day. Low-dose aspirin comes as 75mg tablets, usually taken as 1 tablet once a day.

Taking an extra dose is unlikely to cause problems, the NHS says, but it advises getting medical advice if you take too much because it can sometimes be dangerous. The NHS does not give a threshold amount for when it becomes dangerous, which varies with age, weight, other medicines and health conditions, so any quantity above the packet or prescription instructions should be reported to a pharmacist or to NHS 111.

The NHS gives layered advice. For someone who has taken more aspirin than the packet, leaflet or prescription says and who is otherwise well, speak to a pharmacist as soon as possible. If you cannot speak to a pharmacist, or the medicine was taken on purpose, call NHS 111 for advice.

• Call 999 or go to A&E if the person has lost consciousness, stopped breathing, has severe difficulty breathing, or has a seizure (NHS poisoning advice).

• Call NHS 111 if you are not sure whether something swallowed is harmful (NHS).

• If told to go to A&E, do not drive. Ask someone to drive you or call 999 and ask for an ambulance. Bring the aspirin packet or leaflet inside it, any remaining medicine, and any other medicines you take.

• Do not try to make the person sick, and do not give them anything to eat or drink (NHS poisoning advice).

• Look for what may have caused the problem, and take the substance or its packaging to show doctors, if possible. If the person vomits, putting some in a container may help clinicians identify the cause.

• Start CPR if someone is unresponsive and not breathing, and put them in the recovery position if unconscious and still breathing.

The NHS says that symptoms of poisoning depend on what has caused it, and may take a few hours or days to start, so it is important to get medical advice quickly if there is a chance someone could have been poisoned. General symptoms it lists include feeling or being sick, diarrhoea, feeling sleepy, blurred vision, a high temperature or feeling hot, cold or shivery, confusion, difficulty breathing, seizures and loss of consciousness.

The NHS aspirin page lists indigestion, stomach ache and easier bleeding as common side effects at normal doses, and stomach ulcers or bleeding, shortness of breath or wheezing and allergic reactions as serious ones. These are side effects of normal use, not overdose symptoms, but they are a reason to seek advice and to call NHS 111 if you think you might be having serious side effects.

The sources used for this page do not list overdose symptoms specific to aspirin. A person who has taken a large amount should be assessed whether or not they feel unwell, because the NHS says symptoms may be delayed and that people without symptoms may still need monitoring for several hours.

The NHS says most adults and children aged 16 years or over can take aspirin. It should not be given to children aged 15 or under because of the risk of Reye's syndrome. The NHS lists situations in which aspirin may not be suitable: a previous allergic reaction or serious side effect from aspirin, ibuprofen or another NSAID, a stomach ulcer or a history of them, asthma, heart failure, a liver or kidney condition, and problems with blood clotting.

It also advises that taking aspirin at a higher dose for pain is not recommended during any stage of pregnancy, and not usually recommended while breastfeeding. Other medicines that may not mix well with aspirin include anticoagulants such as warfarin or rivaroxaban, some steroids, some antidepressants, some blood pressure medicines, methotrexate and other NSAIDs. Alcohol can increase the risk of side effects.

Salicylates also appear in other products. The NHS says children under 16 should not be given medicines that contain salicylic acid or salicylate, which includes some mouth ulcer gels, so it is worth checking labels and asking a pharmacist.

Reye's syndrome is a very rare condition that can affect children or young adults after an illness such as flu or chickenpox, and can cause serious brain problems if not treated quickly. The NHS says its exact cause is unknown but it has been linked to the use of salicylates, particularly aspirin, in young people and children under 16.

Symptoms often start 1 to 3 weeks after the child recovers from a virus, and include repeated vomiting, drowsiness, confusion, changes in behaviour, fast breathing, fits and loss of consciousness. The NHS says to call 999 or go to A&E if a child has a fit, has difficulty breathing, is confused, is limp or floppy or loses consciousness, and to tell clinicians if the child has recently taken aspirin. Treatment is in hospital, and most children make a full recovery if treated quickly.

The NHS says poisoning needs hospital treatment, that treatment depends on what has caused it, and that it may include antidotes, a charcoal drink that can help stop some types of poisoning, treatments to help with symptoms such as fluids given into a vein to treat dehydration, and removing what caused the poisoning from the body, which for some substances can involve removing it from the blood. If you do not have symptoms you may not need any treatment but may still be monitored for several hours.

The exact treatment for salicylate toxicity is decided by the hospital team. As a member of the public your role is to get help promptly and to bring the packaging.

The NHS suggests storing medicines and chemicals out of reach of children, ideally in a locked cupboard, and reading the instructions that come with medicines carefully to make sure you take the correct dose. If you take several products for pain or colds, check the labels for overlapping ingredients, and a pharmacist can help you with this.

If you are thinking of harming yourself, aspirin and other medicines are not safe to take in excess. The NHS says to call NHS 111 for advice if you took too much of your medicine on purpose, and to call 999 or go to A&E if someone has lost consciousness, stopped breathing or is having a seizure. A GP can also help with how you are feeling.

Overdose and poisoning are treated through NHS 111, ambulance services and emergency departments. Pharmacists give first-line advice about taking too much of an over-the-counter medicine. Private services do not replace these routes for an overdose; where a private hospital is involved it will normally transfer someone with a significant overdose to an NHS emergency department.