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Paracetamol use may raise asthma risk in children

HONG KONG- Infants who have been given the common pain reliever paracetamol may have a higher risk of developing asthma and eczema by the time they are 6 or 7, a large study covering children in 31 countries has found.

The findings were published in the journal Lancet together with two other studies, which found that runny noses and wheezing early on in life may be strong predictors of asthma.

In the first study, researchers pored through data provided by parents of more than 205,000 children and found paracetamol use in the first year of life was associated with a 46 percent higher risk of asthma by the time the children were 6 or 7 compared to those never exposed to the drug.

Known as acetaminophen in the United States, where it is widely sold under the brand Tylenol, it is used to relieve fever, minor aches and pain, and is used in a liquid suspension for children.

Medium use of paracetamol in the past 12 months increased asthma risk by 61 percent, while high dosages of once a month or more in the past year raised the risk by over three times.

Medium use was defined as once per year or more, but less than once a month.

Suspicions of a possible link between paracetamol and asthma emerged in recent years when experts observed an increased use of the drug to a simultaneous rise in asthma prevalence worldwide.

One theory is that paracetamol reduces antioxidants in the body. Some experts think antioxidants, which stop unstable molecules known as free radicals from doing too much damage, can lower the risk of cancer, heart disease and other ailments.

'Paracetamol can reduce antioxidant levels and ... that can give oxidative stress in the lungs and cause asthma,' one of the researchers, Richard Beasley at the Medical Research Institute of New Zealand, told Reuters in a telephone interview.

As with asthma, monthly use of paracetamol doubled the risk of eczema and trebled that of rhinoconjunctivitis -- repetitive sneezing, rhinorrhea, nasal congestion and hay fever -- by the time children were 6 or 7, the study found.

Paracetamol remains drug of choice

However, the researchers stressed paracetamol should remain the preferred drug to relieve pain and fever in children because its alternative, aspirin, was linked to the risk of Reye's syndrome, a rare but serious complication in children.

'The findings do lend support to the current guidelines of the World Health Organisation, which recommend that paracetamol should not be used routinely, but should be reserved for children with a high fever (38.5 Celsius or above),' they wrote.

Another study in The Lancet found that rhinitis, or hay fever and other allergic reactions causing a runny nose, was a strong predictor of asthma that develops in adulthood.

Researchers monitored 6,461 people in 14 countries who were free of asthma at the start of study for more than 8 years.

Those who suffered rhinitis and were allergic to an assortment of agents like house dust mites, cat, grass and birch were 3.5 times more likely to develop asthma later on compared to those who suffered no allergies nor rhinitis.

The third study in Arizona in the United States found wheezing early in life may be an ominous sign of asthma developing in adulthood.

Researchers pored through data on 849 people going back 22 years to the time they were babies. Of 181 cases of active asthma, 49 were newly diagnosed, of which 35 were women.

'In over 70 percent of people with current asthma and 63 percent of those with newly diagnosed asthma at age 22 years, episodes of wheezing had happened in the first three years of life or were reported by parents at age six years,' wrote the researchers at the Arizona Respiratory Center.

In an accompanying comment, Suzanne Lau of Charite University Medicine in Germany, wrote: 'These findings identify a population at risk of chronic obstructive airway disease in early adulthood, and they already showed a predisposition during preschool years.' Lau was not involved in the study.