It’s not the sandals that cause swollen feet, but rather the weather. Hot temperatures can affect blood circulation, making blood pool in the legs, and this causes swollen feet. At the same time, tight shoes can also restrict normal blood flow, which leads to swollen feet. Lack of arch support might also cause swelling, something you’ll notice when wearing flip flops. Another cause of swollen feet is sitting for many hours at your desk. In winter, when you wear comfy boots you might not notice that much, but in hot weather, which only compounds the problems you will certainly feel the straps of your sandals cutting into the skin.