Although antibiotics may seem safe, using them to fight acute ear infections in their children can boost the risk of recurrent ear infections by 20 percent, according to researchers from the Netherlands.

Findings from a survey show that 63 percent of children given the antibiotic amoxicillin struggled with frequent ear infection within three years, as opposed to 43 percent of kids given a placebo. Researchers said the risk of recurrent ear infection among the amoxicillin users was 2.5 times higher than those non-antibiotic users.

The analysts linked the higher recurrence rate among participants who used amoxicillin to a weakening of their body’s natural immune response as consequence of taking an antibiotic at beginning of infection. The study reveals why physicians must be careful in their use of antibiotics in children with ear infections, as in some cases this treatment can lead to “unfavorable shift” toward the growth of resistant bacteria.