Young adults who take oral antibiotics for acne may be more likely to get sore throats, according to a new study.

While it's not clear that the medications caused the achy throats, researchers say long-term use of antibiotics might change the balance of bacteria in the throat. In principle, that could allow infection-causing strains to multiply.

"These people are more prone to upper respiratory tract infections, but we certainly don't know why," says Dr David Margolis, from the University of Pennsylvania in Philadelphia, who worked on the study.

He points out that people taking antibiotics for acne are generally young and healthy and may take them for months or even years on end - so it's important to be aware of any possible consequences of their use.

So far, though, his research team hasn't seen an extra risk of antibiotic resistance due to acne medications, the most common of which are tetracyclines. And any chance of a sore throat, he adds, may be worth the medication's benefits in many cases.