Doctors from Rutgers and Zurich universities, along with colleagues from New York University, have shown that early exposure to antibiotics in a child can cause asthma and allergies in adulthood. Research published in the journal Nature Mucosal Immunology.
In the first part of the experiment, the scientists gave five-day-old mice water, azithromycin, or amoxicillin. Once the mice grew up, they were exposed to a common allergen from house dust mites. Mice treated with any of the antibiotics, specifically azithromycin, showed an increased immune response, namely allergy. The scientists confirmed this effect by analyzing the blood of mice that showed high levels of IgE and IL-13.
Doctors then tested the hypothesis that early (but not later) exposure to antibiotics causes allergies and asthma by killing some healthy gut bacteria that keep the immune system healthy. To do this, they took stool samples from groups of mice that drank plain water, amoxicillin, or azithromycin as children. They saw no effects in the first generation, but offspring of mice that received bacteria-poor stools were more sensitive to the allergen and increased respiratory reactivity – a sign of asthma.
The authors of the study emphasize that starting drugs later does not affect the occurrence of allergies, so it is not worth stopping them altogether.