Paracetamol use in infancy linked to risk of asthma

Children who take paracetamol during their first two years of life may be at a higher risk of developing asthma by the time they are 18, especially if they have a particular genetic makeup, a study has found.

Small child using his inhaler device for asthma

Research presented at the European Respiratory Society International Congress in Paris showed the link between paracetamol use and asthma seemed strongest in those who had a particular variant of the glutathione S-transferase (GST) gene GSTP1.

But the study stressed that the findings showed only that there was an association between paracetamol and asthma – not that paracetamol caused the lung condition.

Paracetamol is recommended by the NHS to treat most kinds of childhood ailments, including headache, stomach ache, ear ache, and cold symptoms, while it can also be used to reduce fever. The leading brand is Calpol.

The research, carried out at the University of Melbourne, Australia, looked at 620 children who had been followed from birth to 18 years old as part of the Melbourne Atopy Cohort Study.

They had been recruited to the study before they were born because they were considered to be potentially at high risk of developing an allergy-related disease as they had at least one close family member with a self-reported allergic disease such as asthma, eczema, hay fever or a severe food allergy.

After their birth, a research nurse rang the family every four weeks for the first 15 months, and then at 18 months and at two years to ask how many days in the previous weeks had the child taken paracetamol. When the children were 18, they gave a blood or saliva sample, which was tested for variants of the GST genes: GSTT1, GSTM1 and GSTP1.

They were also assessed for asthma, and a spirometry test was performed to measure the amount of air inhaled and exhaled when breathing through a mouthpiece.

Researchers found one variant of the GSTP1 gene – GSTP1 Ile/Ile (in which the amino acid Isoleucine [Ile] is inherited from both parents) – was associated with almost twice the risk of developing asthma.

Neil Pearce, professor of epidemiology and biostatistics at the London School of Hygiene and Tropical Medicine, said: “The idea that paracetamol use early in life may increase the risk of developing asthma has been around for about 20 years. It has been extraordinarily difficult to prove or disprove.

“The problem is that children are not given paracetamol early in life for no reason. They are often given it because they have respiratory infection.

“It may be the infection which increases the risk of asthma, not the paracetamol.”