Paracetamol Poisoning - Causes

Authored by Dr Gurvinder Rull, 09 Jul 2017

Patient is a certified member of
The Information Standard

Reviewed by:
Dr Adrian Bonsall, 09 Jul 2017

There are many reasons for someone to take an overdose. This could be to end one's life or to cause serious self-harm. An overdose can also be taken accidentally - for example, toddlers and people with poor eyesight.

In some, the act of taking an overdose is a spur-of-the-moment thing, whilst in others it can be pre-planned. Those who have pre-planned may have stockpiled medication, sorted out their affairs (such as writing a will) and also written a suicide note.

Paracetamol is widely available from shops and is present in most homes. The government has made rules to limit how much can be bought in one go, which may help reduce the number of overdoses. It is reasonably easy to take and so the government had also ruled that it should only be available in blister packs which can mean the tablets are trickier to get out.

Paracetamol is usually taken by mouth and is available in various ways, such as in tablet, caplet, soluble and liquid forms. They will pass to the stomach and intestine into the body and lead to pain relief and lowering of a high temperature (fever). After this, paracetamol is inactivated before being removed from the body. About 20% of the medicine is processed in the intestinal wall and the remainder in the liver. As a result a small amount of a toxic compound (n-acetyl-p-benzoquinone imine, or NAPQI) is formed in the liver but is quickly detoxified by a substance called glutathione. However in overdose the stores of glutathione can be depleted so that there isn't enough to remove the increased amounts of NAPQI. The NAPQI can then build up and damage the liver.

Some people are at increased risk of liver damage from paracetamol. This includes:

  • Those on certain medications, such as rifampicin, phenobarbital, phenytoin, carbamazepine and alcohol.
  • Those who are malnourished - for example, through chronic illness or eating disorders.
  • Those with alcohol-related liver disease.

Further reading and references

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