The use of antibiotics in the first 12 months of life may increase the chance of developing eczema by up to 40%, according to a new study.

The report also found that each additional course of antibiotics further raises the risk of eczema by 7%.

Researchers reviewed existing data from 20 studies that explored the link between antibiotic exposure prenatally and in the baby's first year, and the subsequent development of eczema. They also examined whether the number of antibiotic courses affected the probability of developing the skin condition.

They found that children with eczema are more likely to have been treated with antibiotics in the first year of life, but not prenatally.

One of the study's authors, Dr Teresa Tsakok of Guy's and St Thomas' NHS Foundation Trust in London, said: "One potential explanation is that broad-spectrum antibiotics alter the gut microflora and that this in turn affects the maturing immune system in a way that promotes allergic disease development."

The paper's senior author, Dr Carsten Flohr of King's College London and Guy's and St Thomas', added: "A better understanding of the complex relationship between antibiotic use and allergic disease is a priority for clinicians and health policymakers alike, as determination of a true link between antibiotic use and eczema would have far-reaching clinical and public health implications."

The study, which was published in the British Journal of Dermatology, was also carried out by researchers from the University of Nottingham and the Aberdeen Royal Infirmary.

The paper added a note of caution, explaining that the use of antibiotics may be a consequence of more infections in children with eczema.

Nina Goad, of the British Association of Dermatologists, said: "Eczema is our most common skin disease, affecting one in every five children in the UK at some stage and causing a significant burden to the patient and the health service. Allergic diseases including eczema have increased over past decades, particularly for children in high-income countries, but the causes for this are not fully understood.

"The evidence is not conclusive and the researchers are not suggesting that parents should withhold antibiotics from children when doctors feel such treatment is necessary, but studies like this give an insight into possible avoidable causes and may help to guide medical practice."

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Baby antibiotics 'link to eczema'