Common painkiller a suspect in child asthma

Photo / Glenn Jeffrey

The use of paracetamol for infants may be linked to the development of allergies and asthma later on, researchers have found.

But more study is needed to clarify this, and the benefits of paracetamol use for fever control still outweigh the potential of later allergy development, said Julian Crane, professor at Otago University in Wellington and author of a report on the subject.

"The problem is that paracetamol is given quite liberally to young children," he said.

"There's a lot of evidence suggesting that something is going on here. It's not completely clear-cut, that's the problem."

The report, which has appeared in Clinical and Experimental Allergy journal, is based on the New Zealand Asthma and Allergy Cohort Study, which investigated the use of paracetamol on 505 infants in Christchurch and 914 5- and 6-year-olds also in Christchurch to see if they developed signs of asthma or allergic sensitivity.

"The major finding is that children who used paracetamol before the age of 15 months were more than three times as likely to become sensitised to allergens and twice as likely to develop symptoms of asthma at 6 years old than children not using paracetamol," Professor Crane said.

"However, at present we don't know why this might be so. We need clinical trials to see whether these associations are causal or not, and to clarify the use of this common medication."

The research found that by 6 years of age, 95 per cent of the study sample was using paracetamol and there was a significant increased risk for asthma and wheezing.

But the findings depended on how much paracetamol was being used, and the risk was greater for those with severe asthma symptoms.

Professor Crane said there were few other options for fever control in young children, noting that aspirin had dropped out of favour over the past 30 years due to links between aspirin use and the potentially fatal illness Reye's syndrome in children.

"That timing fits quite well with the rise in the prevalence of allergies, but that may just be coincidence," Professor Crane said.

He said that in the absence of other options and studies establishing a firm causal link, paracetamol should still be used for now.

"If I had a child with a fever, I'd give them paracetamol," he added.

Auckland University's paediatric head of department Professor Innes Asher leads the International Study of Asthma and Allergies in Children.

She said this latest research was consistent with most other international observational studies.

It should be taken as a timely reminder to parents that the drug should be used sparingly - to treat high temperatures and severe pain.

"Children who have mild aches and pains usually need no drugs whatsoever, they just need some comforting," Professor Asher said.

"You shouldn't be using it at the drop of a hat."

Clinical trials over several years would hopefully solve the question of whether the drug was a cause of asthma and allergies or whether those children would have developed those problems anyway.

"There's no grounds to stop using it, it's not regarded as unsafe but it just shows all drugs that we use can have some downsides as well as some upsides."

Pharmaceutical company GlaxoSmithKline did not return Herald calls.

However, Tim Roper from trade association New Zealand Self-Medication Industry Association said paracetamol had a 50-year history of safe use in children.

Mr Roper said it was important to note that the link between the drug being taken and asthma could not be directly related.

"The benefit of paracetamol taken appropriately in the correct dosage outweighs any risks of increasing the possibility of asthma later in the child's life."

However, Mr Roper also advised parental caution. Caregivers needed to ensure overuse, especially for young children, was not a factor.

Other specialists said overdoses could be dangerous.

Professor Crane said that while the study showed a link between the medication, asthma and allergies, there were many other factors to consider.

Guidelines for its use were not clear, he said.

Gasping for air

* One in six New Zealand adults and one in four of children - more than 600,000 people - has asthma symptoms.

* Asthma is the most common cause of admission to hospital for children.

* Severe asthma is common - up to 8 per cent of teenagers report a wheeze limiting their speech, and 10 per cent of adults report waking with breathlessness.

* In 2006, according to the Ministry of Health, 132 New Zealanders died from asthma.

- Source: asthmanz.co.nz