Paracetamol link to asthma risk

Paracetamol link to asthma risk 'has been overstated': Experts say evidence is not strong enough to warrant warnings

• Previous studies claimed exposure to paracetamol in the womb or during early months of life leads to a greater chance of developing asthma
• But new research suggests respiratory infections play a key role
• Experts say evidence not strong enough to warrant warnings about drug

Fears that babies given Calpol and other forms of paracetamol are more likely to develop asthma may be exaggerated, say scientists.
Previous studies have claimed that exposure to the drug – in the womb or during early months of life – leads to a greater chance of developing the condition. 
But new research suggests that respiratory infections play a key role – and the evidence is not strong enough to warrant warnings about restricting use of the drug by pregnant women or infants.

Scientists say fears that babies given paracetamol are more likely to develop asthma may be exaggerated
For example, children with more severe respiratory infections – who are also more likely to develop asthma - may have been given more medication as a result.
The link between paracetamol, also known as acetaminophen in the US, has been ‘overstated’ says a review of the current evidence published online in the Archives of Disease in Childhood.
They researchers looked at published evidence, spanning a period from 1967 to 2013, and considered 11 suitable for analysis.
The seven studies covering the potential link between exposure to paracetamol while in the womb and subsequent childhood asthma reached widely varying conclusions, and only one took account of the potential role of respiratory infections during pregnancy.
Six of the studies looked at exposure to paracetamol during the first two years of life—a critical period for lung development.
Although these studies consistently pointed to a link between the drug and asthma, it became weaker after respiratory infections during infancy were accounted for.
A link found between the number of times a child had been given paracetamol and that child’s asthma risk all but disappeared when respiratory tract infections were taken into consideration.
This makes ‘it unlikely that paracetamol is a clinically important risk factor asthma’ because the evidence is ‘weak’, said the research team led by Allergy and Lung Health Unit at Melbourne University, Victoria, Australia.







The link between paracetamol has been ‘overstated’ says a review of the current evidence published online
A proper trial looking at whether paracetamol can trigger asthma is highly unlikely as some babies would have to be given a dummy pill, which many parents would refuse, say the researchers.

They conclude ‘The evidence of an association between early life paracetamol and asthma is often overstated, and there is currently insufficient evidence to support changing guidelines in the use of this medicine.’
It had been thought paracetamol may cause changes in the body that leave children more vulnerable to inflammation and allergies.

Dr Samantha Walker, Director of Research and Policy at Asthma UK, said ‘We welcome the findings of this report which concludes that an association between early life exposure to paracetamol and asthma has probably been overstated.


Six of the studies looked at exposure to paracetamol during the first two years of life—a critical period for lung development
‘According to the study authors, the current evidence for a link between the drug’s use and the development of asthma is ‘weak’ and so parents should not worry about taking paracetamol during pregnancy or giving it to young children.

‘Research like this is welcome because despite asthma affecting 1 in every 11 children, years of research underfunding means it remains a relative mystery.
‘These findings provide reassurance to parents of young children that paracetamol is a safe and effective treatment for pain and fever if taken according to the manufacturer’s directions.’

Prof Seif Shaheen, Clinical Professor of Respiratory Epidemiology at Barts and the London School of Medicine and Dentistry, Queen Mary University of London, said his team first reported a link between paracetamol use and asthma 14 years ago.
He said a large number of epidemiological studies have since confirmed associations with use in pregnancy, early childhood and later in life.

He said ‘Whilst the jury is out regarding whether the link between infant paracetamol use and childhood asthma is confounded by respiratory infection, there is no evidence to suggest that respiratory infections in pregnancy confound the association between prenatal exposure and asthma.

‘Given that primary prevention trials may never happen, I would argue that there is nothing to be lost by advising pregnant women and parents of young children to minimise the use of paracetamol.
‘Paracetamol is probably overused and it would seem prudent to discourage unnecessary or inappropriate use at the present time.’