Q. Do repeated courses of antibiotics reduce the ability of the immune system to fight future infections? My 5-year old has had several throat infections that seem to return after each antibiotic course has finished.

A. Immune responses aren’t affected by a person being given repeated courses of antibiotics, so they haven’t harmed your son. However, there must be a reason for him having so many infections: discuss him with your doctor. Remember that at 5, he has come into contact for the first time, possibly, with a whole host of new strains of germs at school. This is his peak year for catching throat infections – they will probably lessen over the next year.