Acne and the use of oral antibiotics to treat it are so common that these patients represent "an ideal group in which to study the effects of long-term antibiotic use," University of Pennsylvania researchers write.
Their findings are published in the Archives of Dermatology.
About 2 million Americans are treated for acne every year, according to the researchers.
"People taking antibiotics for acne tend to be on them for months, if not years," says study researcher David Margolis, MD, PhD, a professor of dermatology.
The basic premise was that the use of long-term antibiotics might change the mix of bacteria in the throat, perhaps leading to a sore throat. It turns out it's not that simple.
Antibiotics and Sore Throats
A few earlier studies have suggested a connection between antibiotic therapy for acne and an increased risk of a sore throat. But the new research is the first that follows patients over time, Margolis and colleagues write.
The researchers conducted two studies. The first study looked at college students who met with researchers at single visits in January and February 2007.
In this study, 10 of 15 students taking oral antibiotics for acne reported having a sore throat in the previous month, while only 47 of 130 students who had acne but weren't on oral antibiotics did.
The second study followed a separate group of close to 600 students for several visits over the 2007-2008 school year. Of that group, 36 took oral antibiotics for acne, while 96 used topical antibiotics for acne.
About 11% of the students taking oral antibiotics for acne said they had gone to the health center for a sore throat, compared to only about 3% of the other students. The students using topical antibiotics were no more likely to report having a sore throat than those who weren't on any antibiotic therapy.
Checking for Strep
Besides asking the students about whether they'd had sore throats, the researchers also checked them for the bacteria strep. Only about 10% of sore throats are caused by bacterial infections, the researchers write, but of these, strep causes 90%.