What causes a blister?

A blister is caused by intense friction on the skin, usually from shoes or socks/hosiery. Your feet are used to friction and rubbing when you walk but you wouldn’t usually get any blisters. Blisters will usually occur when you do something different to normal, such as:

• Wear a new pair of shoes. A common cause of blisters, new shoes can cause rubbing that the feet are not used to. New shoes can also be quite stiff and so rub even more.
• Do a new activity – or the same activity for longer. If, for example, you take up a new sport, or if you run 20 miles instead of your usual 5 miles, your socks and shoes will rub a lot more than normal and a blister can develop.
• Have sweaty feet, e.g. in hot weather. Skin that is moist is more likely to get a blister because the skin sticks to the material of the shoes.
• Wear shoes without socks or hosiery. Socks and hosiery can help to reduce friction because they can help the shoe to slide over the skin without rubbing against it. They also absorb sweat so help keep the skin dry and less likely to blister.