How long does it take for blisters to heal if it is not treated?

Natural Healing: When there is injury to our skin, inflammation occurs which means the area becomes red, warm, tender and with swelling. The swelling occurs under the skin layers and causes them to bulge creating a protective fluid cushion we call a blister. As the area heals, the fluid will be resorbed or when no longer needed, the blister opens and the fluid drains. This should take about a week.