The risk of eczema may be linked to antibiotics during a child's first year, researchers believe.
A new study suggests the use of antibiotics in the first 12 months of life may increase the chance of developing eczema by up to 40%.
And each additional course of antibiotics further raises the risk of eczema by 7%, according to the team led by Dr Carsten Flohr of Guy's and St Thomas' NHS Foundation Trust in London.
The researchers, who did not suggest that parents should withhold antibiotics from children when doctors feel such treatment is necessary, published their findings in the British Journal of Dermatology.
Dr Flohr said: "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 team - based in London, the University of Nottingham and Aberdeen Royal Infirmary - reviewed existing data from 20 studies. They found that children with eczema are more likely to have been treated with antibiotics in the first year of life - but not prenatally.
Dr Teresa Tsakok, one of the study's authors, 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."
Adding a note of caution, the paper explained that increased use of antibiotics may be a consequence of children with eczema having more infections.
Cases of allergic diseases in general, including eczema, have been more widespread over recent decades, particularly for children in high income countries. However, the causes for this are not fully understood, said Nina Goad of the British Association of Dermatologists.
She added: "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."
Copyright Press Association 2013