Although popular and comfortable, flip flops have never been favorites among foot doctors. The flat shoes aren't good for arches and don't offer any support, which could lead to ankle injuries. Kathya Zinszer, associate professor of podiatric medicine and director of community outreach at Temple's School of Podiatry, says that feet can also slide around, which can cause blisters. While she doesn't fully rule out flip flops, she does tell her patients to choose wisely. "You want to know when to wear flip flops, and you need to really consider what the risk factors are," she said.