Q: What are blisters? A: Blisters are the accumulation of fluid between the inner and outer layers of the skin. They are rarely a serious concern but can become infected and more problematic if not treated correctly. They are often caused by prolonged friction between your foot, socks, and shoes. A blister should be drained, by sterile technique, as soon as possible. If blisters are excessively painful, persistent, or infected, see your doctor or podiatrist for treatment. Wearing dual-layer or blister-free socks will minimize friction and moisture, and help keep you less susceptible to blister formation. Neoprene insoles may also help reduce friction.