Friction blisters of the skin commonly occur in active populations. They are the result of frictional forces between the involved skin area and the object with which the skin is in contact. Friction blisters create localized discomfort; however, they should not be taken lightly because secondary impetigo may become a serious complication with resulting cellulitis and sepsis. 
The bulk of research on friction blisters comes from the military because of the nature of the physical activity involved in this field. Friction blisters have also received much attention in the field of sports medicine.
See the image below.
The influence of epidermal hydration on the friction of human skin against textiles was studied. Increasing cutaneous hydration may cause sex-specific changes in the mechanical properties and/or surface topography of human skin, leading to skin softening and increased real contact area and adhesion. 
Studies involving rubbing the skin with a constant force show an initial slight exfoliation of the skin over the involved area. Focally, mild erythema also develops. The patient may experience stinging or burning, while a zone of pallor develops around the erythematous area. The pallor eventually extends into the region of erythema and this area develops into a blister.
The effect of wearing socks with different frictional properties on plantar shear was studied because this is a possible mechanical risk factor for foot lesion development.  Wearing socks with low friction against the foot skin reduced the plantar shear force on the skin more than a sock with low friction against the insole.
Friction blister formation is affected by epidermal hydration. In a study of 11 men and 11 women, the friction between the inner forearm and a hospital fabric was measured in different hydration states.  Increasing skin hydration caused sex-specific changes in the mechanical properties and/or surface topography, as the friction of female skin demonstrated significantly higher moisture sensitivity.
Technology such as thermographic images may facilitate assessment of traumatically damaged foot skin. 
During the first Iraqi War, the prevalence of foot friction blisters among American troops was 33%, of which 11% required medical care. 
No known predilection is reported for any particular race.
No known predilection is described for either sex. Women aged 26-34 years who are unable to break in their boots and have a past history of blisters, were the most likely to develop friction blisters among American troops during the first Iraqi War. 
No known predilection is apparent for any age group.
Friction blisters create localized discomfort; however, they should not be taken lightly because secondary impetigo may become a serious complication with resulting cellulitis and sepsis.
Educate patients about the importance of prevention measures (see Deterrence/Prevention).