Is That What My Foot Blister Is - A Burn Blister?

by Rebecca Rushton

There's a popular belief that foot blisters are a burn. That rubbing burns the skin. It sounds feasible ... rubbing two sticks together can generate enough heat to start a fire! But can rubbing overheat the skin so much that it burns? 

 

burn blister

 

Rubbing increases skin temperature

Rubbing any two surfaces together causes heat and rubbing the skin is no different. It's easy to assume that the more rubbing there is and the more heat generated, the closer it can get to burning the skin. However, research has found that rubbing causes only mild skin temperature increases, insufficient to burn.

In his experimental blister research in 1955, Naylor compared blister rates at two rubbing speeds - the faster rubbing speed did not cause blisters to form any quicker than the slower rubbing speed. Separately, he compared two materials that differed in thermoconductivity to provide the rubbing (one had the ability to absorb heat away from the skin, keeping it cooler). No difference in blistering rate was found!

 

Skin temperature appears to be a minor factor in blister formation. Blisters form somewhat more rapidly when the skin temperature is higher but blisters also occur when the skin temperature is low. In experimental rubbing studies, local heat is produced and skin temperatures have been reported between 41 degrees Celsius and 50 degrees Celsius. However, friction blisters do not resemble second degree thermal burns either clinically or histologically.

Knapik et al (1995)

 

Friction blisters are not a burn blister

The relevance of heat?

Friction blisters on the feet are more common in warmer temperatures. But blisters can occur in cold temperatures too (Griffin et al, 1969; Akers, 1977; Knapik et al, 1992). Griffin et al (1969) produced experimental blisters on chilled, warmed and “normal” temperature skin and noted:

  • blisters formed quicker when initial skin temperature was higher
  • blisters took longer to form on chilled skin (14 degrees) compared to normal (30 degrees) and warmed skin (46 degrees)
  • when the initial skin temperature was low, the skin temperature at the time of blistering was also lower

     

    Why do people say blisters are caused by heat, moisture and friction?

    As the feet get warmer with exercise, the skin sweats. This perspiration is moisture. Moisture increases friction levels (Nacht et al, 1981; Naylor, 1955). And higher friction levels lead to increased incidence of blisters. For more information, read What Causes Blisters.

     

    Blisters are not a burn blister, they're an epidermal fatigue

     

    What causes blisters?

    Blisters occur when shear (stretching of the skin) causes a tear under the skin's surface. Sulzberger and Akers determined this in 1972. And Comaish confirmed it the following year as he ruled out other potential causes (wear, heat, enzymes, pressure, stretching or ischaemia). He called it epidermal fatigue.

     

    Conclusion

    It is in spite of the efforts of the earliest blister researchers (and researchers since) that this myth persists! 

     

    References

    Akers, WA and Sulzberger MB. 1972. The Friction Blister. Military Medicine. 137:1-7.

    Akers, WA. 1977. Sulzberger on Friction Blistering. International Journal of Dermatology. 16: 369-72.

    Comaish, JS. 1973. Epidermal Fatigue as a Cause of Friction Blisters. The Lancet. Jan 13: 81-83.

    Hashmi, F, Richards, BS, Forghany, S, Hatton, AL and Nester, CJ. 2013. The Formation of Friction Blisters on the Foot: The Development of a Laboratory-Based Blister Creation Model. Skin Research and Technology. 19: e479-e489.

    Knapik, JJ, Reynolds, K, Duplantis, KL and Jones, BH. 1995. Friction blisters – pathophysiology, prevention and treatment. Sports Medicine. 20 (3): 136-147.

    Nacht, S, Close, J, Yeung, D and Gans, EH. 1981. Skin friction coefficient: changes induced by skin hydration and emollient application and correlation with perceived skin feel. Journal of the Society of Cosmetic Chemists. 32 (March-April): 55-65. 

    Naylor, P. 1955. Experimental friction blisters. British Journal of Dermatology. 67: 327 – 42.

    Naylor, P. 1955. The skin surface and friction. British Journal of Dermatology. 67: 239 – 48.

    Richie, D. 2010. How to manage friction blisters. Podiatry Today. 23 (6): 42-48.





    Rebecca Rushton
    Rebecca Rushton

    Author

    Podiatrist, blister prone ex-hockey player, foot blister thought-leaderauthor and educator. Can’t cook. Loves test cricket.


    Leave a comment


    Also in Blister Blog

    How To Treat Blisters On Feet: Avoid These Blister Treatment Fails [Warning: Graphic]
    How To Treat Blisters On Feet: Avoid These Blister Treatment Fails [Warning: Graphic]

    by Rebecca Rushton

    It's difficult to get people to take blister treatment seriously. So we're starting this article with 6 blister treatment fails that show you why it's important to treat a blister on your foot properly. 

     

    View full article →

    black toenail big toe
    How To Treat Black Toenails

    by Rebecca Rushton

    Some black toenails are painless, others are extremely painful. Releasing the blood brings instant relief. You can do this quite easily and painlessly by drilling a hole in the nail with a hypodermic needle.

     

    View full article →

    Gel toe protectors: gel toe caps and toe sleeves
    Gel Toe Protectors: Gel Toe Caps & Toe Sleeves

    by Rebecca Rushton

    I like to say Gel Toe Protectors are 100x better than taping for blister. There are two reasons why. But gel toe caps & toe sleeves do have their downsides.

     

    View full article →