Blisters will — eventually — render you ineffective. Blisters are caused by burns, allergies, skin conditions or bites. The most common cause is friction. Cell damage occurs when there is enough friction in a focused spot. The fluid inside a blister protects and heals the damaged tissue. Several things that make blisters more likely to occur: Pressure: Tight spot in your boot or a wrinkle in your sock could create friction pressure...