There are many causes for blisters on feet including friction, contact dermatitis, burns or allergic eczema. Blisters often form due to the friction of improperly fitting footwear.
Serious causes of blisters include impetigo, chickenpox, shingles, herpes or erysipelas. These are all a different kind of infection caused by viruses or bacteria and need to be treated for directly in order for blistering to subside. Blisters can also form due to exposure to extremely hot or cold temperatures and may last up to four days. For recurring blisters, the underlying cause may be a skin condition such as porphyrias, pemphigus, dermatitits herpetiformis or epidermolysis bullosa.