Babies given antibiotics before they are a year old are 40 per cent more likely to develop eczema, according to new research.
Each additional course of antibiotics further raises the risk of eczema – which affects one in five children in the UK – by 7 per cent.
Researchers from Guy's and St Thomas' NHS Foundation Trust, King's College London, the University of Nottingham and the Aberdeen Royal Infirmary reviewed data from 20 studies involving almost 293,000 babies and children.
About 2.4million of the UK's 12million children have been diagnosed with the disease, caused by an over-active immune system and resulting in dry and itchy skin.
Senior researcher Dr Carsten Flohr, of King's College and Guy's, said some previous studies had implied a link, but this was the first systematic large-scale review.
He said: "We found antibiotic exposure in early life may increase the risk of subsequent eczema by up to 40 per cent, with broad-spectrum antibiotics having a more pronounced effect. It's a real effect.
"Having antibiotics in the second year of life is less likely to be important, but we don't have the studies to examine it."
Dr Flohr recommended that antibiotics should be prescribed 'with caution', especially to infants with a family history of eczema or allergic disease.
But he stressed: "Doctors usually have good reason to prescribe antibiotics to infants.
"The importance of this finding is to get a better understanding of the complex relationship between antibiotic use and allergic disease.
"We need further research as determination of a true link between antibiotic use and eczema would have far-reaching clinical and public health implications."
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