Children who take antibiotics throughout their childhood may have a significantly greater risk of weight gain in adolescence compared to those who take no antibiotics, particularly with a specific antibiotic class of drugs, according to a study in the International Journal of Obesity.

Brian S. Schwartz, MD, from the Johns Hopkins Bloomberg School of Public Health, and colleagues reviewed electronic health record data on 163,820 children aged 3–18 from January 2001 to February 2012 on antibiotic use in the previous year and annual body mass index (BMI), controlling for confounders. Any data on antibiotic use in prior years was also analyzed, if available.

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By age 15, those who had received antibiotics seven or more times during their childhood weighed on average 3lbs. more than those who had received no antibiotics; about 21% of the children in the study met this criteria. There was a persistent association seen between antibiotic treatment and weight gain that was stronger with increasing age, with the most significant weight gain observed at age 15 with macrolide use.

“Systematic antibiotics should be avoided except when strongly indicated,” Schwartz said in a statement. “From everything we are learning, it is more important than ever for physicians to be the gatekeepers and keep their young patients from getting drugs that not only won’t help them but may hurt them in the long run.”

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