Guidelines for the management of acute paracetamol overdosage

Paracetamol is among the substances most frequently listed in telephone enquiries or attendances for suspected overdoses in infants, probably because it is one of the most frequently used medicines for infants in the home, but this may lead to misconceptions about its safety. In fact, paracetamol liquid preparations have a remarkable safety record, and it is rare for a child to suffer any toxicity, but because parents present infants at hospital, although they are not actually at risk, they add to the statistics for suspected overdose. It is easy to understand their anxiety; diligent parents may take turns at looking after a sick toddler and become confused about how much medicine they have given, and naturally become concerned and seek medical advice. Similarly, bottles of liquid medicine may be left unattended for a moment while a telephone is answered or kettle switched off, only for a mother to return and find the child with a spilt bottle and liquid around its mouth. Again, and particularly in view of dramatic media articles about paracetamol overdose, distraught mothers rush to their nearest hospital A & E unit. Although they return home with their loved one safe and sound, they have become part of the statistics.

It is a self perpetuating process, the higher the statistics, the more warnings are given, the more likely parents are to react to possible overdose scenarios.

But this is all very misleading. Certainly paracetamol overdose became an 'issue', but the issue is one of deliberate self harm and suicide in adults or, tragically but rarely, young adults. The average age of people who overdose on paracetamol is around 40. Now, thankfully, the problem is diminishing following 1998 legislation on pain reliever pack sizes.

However, there has never been a problem of serious accidental overdose with paracetamol in the under fives. Children under five are treated with paracetamol liquid formulations, and, as the National Poisons Information Service advise hospitals in the UK, 'Paracetamol poisoning with children's liquid preparations is rarely serious.' (1)

Data from the National Office for Statistics covering England and Wales shows that over the last ten years there have been no fatalities in the under fives from paracetamol poisoning.

A study (2) of six hospitals in the North East of England in 1994 stated that presentation to hospital with suspected paracetamol poisoning is common in children but it is unusual for children to ingest sufficient paracetamol to cause toxicity. This is supported by other studies both in the UK and the US. (3,4) The authors suggest that because of the rarity of serious paracetamol poisoning in the under fives it appears unnecessary to perform plasma paracetamol measurements unless it is known they have ingested large doses (i.e. more than 150mg/kg body weight). This advice is also given by the current guidelines set by the National Poisons Information Service.

An Australian study (5) of paracetamol poisoning in children stated that although paracetamol is one of the most common drugs that children accidentally ingest, death and hepatotoxicity in children from paracetamol poisoning are 'exceedingly uncommon events'.

Similarly, a study (6) over three years of children in the USA reported 218 children were presented at the hospital with suspected accidental paracetamol elixir ingestion, but no child showed any sign of paracetamol toxicity. The authors again comment that, 'Morbidity and mortality after accidental (paracetamol) ingestion in young children are extremely low'.

This is not to say that vigilance in safety in the use of paracetamol products where children are concerned should be relaxed in any way. However, there is clearly a misconception about the dangers of accidental paracetamol overdose in the under fives, and parents should be reassured about the safety of liquid paracetamol products.

References:

1. Guidelines for the management of acute paracetamol overdosage 2003 NPIS

2. Paracetamol poisoning in the North East of England: presentation, early management and outcome, Thomas SH. L. et al., Hum. & Exp. Tox. (1997), 16: 495-500.

3. Acetaminophen overdose in young children. Treatment and effects of alcohol and other additional ingestants in 417 cases, Rumack BH, Am. J. Diseases of Children (1984), 138: 428-433

4. Paracetamol overdose in children, Kumar A et al., Scott. Med J. (1990), 35: 106-107

5. Paracetamol poisoning in children and hepatotoxicity; A Penna & N Buchanan, Br. J. Clin. Pharmacol. (1991), 32: 143-149

6. Predicting concentrations in children presenting with acetaminophen overdose; B J Anderson et al., J. Paed. (1999), 135(No 3): 290-295