If the blister is exposed to friction for an extended period of time, it may take many weeks to heal. Meanwhile, the blister may rupture on its own, spilling fluid. This also exposes the blister to infection. It is important to pop any new blister as soon as it forms so that exposure to heat or moisture does not cause it to open up and leak. Newly formed blisters should be cleaned with a clean damp cloth and sprayed with an antibacterial spray to kill any bacteria that may be present. The cloth should then be washed again after being used to clean another person's wound. Pop your blister! Blisters are created when the skin is trapped under a hard surface, such as pavement, and develops a white color on the inside while remaining dark outside. This is normal; there is no need to worry about it. But if the blister isn't popped within 24 hours of forming, it can become a breeding ground for bacteria that may lead to infection. Bacteria may also enter the body through the skin of the foot where there are no visible signs of injury. You can be infected with HIV even without knowing it. Infected blisters may appear red, swollen, and painful. They may also be hot to the touch. If you develop any type of skin problem on your feet, call your doctor immediately.