Paracetamol overdose is common and may occur accidentally or in the context of self-harm. Significant overdose can result in liver failure if not promptly treated with the antidote.
How does paracetamol in overdose cause problems?
Paracetamol is usually taken by mouth and then passes through the stomach and intestines. It can then exert its pain-relieving and temperature-reducing effects. After this, paracetamol undergoes a number of processes to inactivate it. One by-product of these reactions is toxic to the liver, but only in an overdose is enough formed to cause damage.
Some people are at increased risk - for example, malnourished patients or people who have alcohol dependency.
Read more about the causes of paracetamol poisoning.
Is it serious?
Paracetamol is the most common medicine taken in overdose. It can lead to liver failure in a number of days, despite using medication to protect the liver. Liver failure can be fatal.
Over 150 people die each year as a result of a paracetamol overdose.
Find out more about the symptoms of paracetamol poisoning.
What do I feel when it happens?
You may not have any symptoms in the first 24 hours after taking the overdose or you have a feeling of sickness (nausea) or are sick (vomit). After 24 hours the liver may become involved and you may have pain under the ribs on the right-hand side where the liver sits and you may notice a yellow colour in your skin or the whites of your eyes (a condition called jaundice).
Paracetamol overdose can also lead to low blood sugar (hypoglycaemia), confusion and kidney failure. Kidney failure may lead to a low urine volume.
Read more about the symptoms of paracetamol poisoning.
Do I need any further tests?
Yes - you will need blood tests including blood paracetamol levels, kidney function, liver function and blood clotting. These blood tests are likely to be taken frequently.
Paracetamol levels need to be taken four hours after the time of overdose. If the time is not known and the paracetamol tablets were taken in one go then a baseline level is sometimes taken followed by a repeat test four hours after coming to the hospital. Sometimes treatment may be started before these tests are taken.
If excessive amounts of paracetamol have been taken over several hours or days this is called a 'staggered overdose'. In this case the paracetamol levels become less reliable and you will be treated and monitored despite the levels.
Learn more about the diagnosis of paracetamol poisoning.
How is it treated?
The patient will need to be stabilised to begin with and resuscitated immediately if there are any life-threatening features. They may need to be moved to an intensive care unit, especially if there are features of liver failure.
Treatment will require an intravenous infusion of a medicine called N-acetylcysteine (NAC). This medicine is mixed in intravenous infusion fluid and given usually via three bags over approximately 24 hours. During that period several blood tests may be taken to monitor the liver and kidneys. Once the medicine is finished, a further blood test will be taken and if this is normal, the patient may need to be reviewed by the psychiatry team before being discharged.
If the blood tests remain abnormal then the NAC treatment will need to continue. If there is liver failure then the patient may need to be moved to a specialist liver unit where they will be monitored further and be considered for an urgent liver transplant.
Read more about the treatment of paracetamol poisoning.
Further reading and references
Self harm and poisoning by sex, 2014-15; Health and Social Care Information Centre (Link to downloadable file)
Hawton K et al; Impact of different pack sizes of paracetamol in the United Kingdom and Ireland on intentional overdoses: a comparative study. Biomed central (2011)
Paracetamol overdose - revised single line treatment nomogram; Medicines and Healthcare products Regulatory Agency, Sept 2012
Ferner RE, Dear JW, Bateman DN; Management of paracetamol poisoning. BMJ. 2011 Apr 19342:d2218. doi: 10.1136/bmj.d2218.
Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions. Patient Platform Limited has used all reasonable care in compiling the information but make no warranty as to its accuracy. Consult a doctor or other health care professional for diagnosis and treatment of medical conditions. For details see our conditions.