Experimental and clinical pharmacology
Paracetamol: overused in childhood fever
- Peter Hewson
- Aust Prescr 2000;23:60-1
- 1 March 2000
- DOI: 10.18773/austprescr.2000.063
Paracetamol has a mild beneficial effect on the symptoms of viral illness in childhood. However, the child may still remain unwell. Data suggest that fever may have an immunological benefit and that paracetamol may not decrease the number of recurrent febrile convulsions. There are good reasons, particularly related to toxicity, for limiting the use of paracetamol in children.
Some years ago Frank Shann warned us of the routine use of paracetamol in febrile young children.1 (See also 'Paracetamol: use in children' Aust Prescr 1995;18:33-5). Evidence continues to mount against its indiscriminate use. The mild symptomatic benefit must be balanced against the increasing incidence of mistaken dosage and toxicity. As we live in a society which relies on drugs, both doctors and pharmacists should remind parents about the dangers of paracetamol.
Reasons for caution
Humans and other animals given paracetamol are likely to shed virus for longer than controls.2
Several factors increase the risk of toxicity.
It has previously been mistakenly accepted that all febrile children with infective illness require medication. We need to question this phenomenon as another example of society's reliance on drugs. The widespread use of antipyretic drugs (mainly paracetamol) means that mistakes in dosage will inevitably occur.
Parental fever phobia has been documented.3 Parents and doctors understandably need to feel they have something to offer sick, miserable children. However, cuddles, comfort and fluids are likely to be a safer and healthier alternative to drugs.
Whilst the frequency and dangers of intentional paracetamol over dosage are well known4, until recently, only occasional accidental overdoses were reported. However, a recent report found that over a 13-year period 11 of 18 cases of fulminant hepatic failure were associated with accidental paracetamol ingestion. Two children died and one suffered serious neurological sequelae.5 In another study of 47 children who were mistakenly given toxic doses of paracetamol 24 (55%) of the children died.6 In the UK, package restrictions limiting the number of tablets per package have been introduced in an attempt to decrease the risk of self-poisoning. Similar steps may be necessary to minimise accidental over dosage in children.
The toxicity appears to occur when maximum total per kilogram daily doses are exceeded (90 mg/kg/day) and when repeated doses are given to children with pre-existing liver disease e.g. viral hepatitis.
There are 23 non-tablet paracetamol preparations available on the Australian market. The available mixtures have various strengths including 24 mg/mL, 50 mg/mL and 100 mg/mL. An 8 kg infant only requires three mistaken 5 mL doses of the 100 mg/mL infant preparation (instead of the 24 mg/mL paediatric mixture) before a potentially hepatotoxic dose is reached (more than 150 mg/kg/24 hours).
Difficulty in proving benefit
The best study investigating the possible symptomatic benefits of paracetamol compared the drug to placebo.7 The double-blind trial, using parental observations, analysed 225 febrile children's mood, comfort, appetite, fluid intake, activity and alertness. In the paracetamol treated group, activity and alertness significantly improved by one grade, mood and eating improved but not significantly, while drinking was worse. The parents' descriptions of comfort were equal in both groups. Interestingly, parents were unable to tell whether their child had been treated with paracetamol or placebo. The duration of fever was the same in both groups. Thus while some benefit was obtained, it does not justify its use if the risk of toxicity is real.
Difficulty in proving worth in preventing febrile convulsions
Febrile convulsions are associated with higher temperatures8,9, but it is not known if lowering the temperature would have prevented these convulsions. Rate of rise of temperature is also thought important as 25% of convulsions seem to occur prior to, or at the commencement of, the fever. Previously, antipyretic prophylaxis has not been shown to be effective in reducing febrile seizures.10,11
Early data suggested antipyresis (including sponging) was of limited benefit in preventing recurrent febrile seizures. Further evidence now suggests that sponging does bring down the temperature faster than paracetamol or ibuprofen in the first 30 minutes, however, the effect of the drugs lasts for longer.12
Other medication options
Ibuprofen has been shown to be at least as effective as paracetamol13,14 but is more likely to produce gastrointestinal and renal adverse effects. One suspects that if ibuprofen is used as widely as paracetamol then inevitably its toxicity and adverse effects will become a problem.
Further population studies are required to establish the safety and pitfalls of a regimen using a limited number of doses of paracetamol and/or ibuprofen.
While aspirin is also effective, its widespread use cannot be recommended because of its gastrointestinal and platelet effects, and an association with the rare Reye's syndrome.
Paediatrician, Geelong, Vic.