For most runners, blisters are only a problem when mileages start to increase, for example when doing long runs in preparation for a marathon.
However, while they are one of the most common sports injuries, research has revealed that only about ? % of all injuries that resulted in a one week interruption of training were actually caused by blisters.
Quite simply, blisters are caused by friction. The combination of friction and excessive moisture - as in a runner's sweaty socks! - creates the right conditions for blisters to form.
That means that the best prevention for runners is the right socks and shoes. In particular:
Avoid cotton socks - cotton retains moisture and will keep your feet damp. Opt for modern moisture wicking fabrics that will keep your feet dry.
Shoes - your shoes should fit properly. Take care when 'running in' a new pair of shoes, as they may rub your feet differently.
Many long distance runners use Vaseline or Bodyglide on friction areas such as the toes and feet, as well as inner thighs, underarms, and even nipples.
Opinion varies as to treatment. The skin over the irritated area provides protection from infection, so if you can leave it intact, that will be better. However, larger blisters, or more painful ones, sometimes need to be punctured.
Be sure to use a sterile needle to do this, and once you have drained the fluid, apply an antibiotic cream or an antiseptic and a sterile dressing.
Diabetics should not do this themselves, but should instead consult their doctor.