What are blisters?

Question

So I got some blisters on my feet from my shoes, and while I was trying to take care of them, the thought occurred to me..what the hell are these? Is the liquid inside water or plasma? Are they always caused by some type of friction?

Answer 1

There are several reasons why you can get a blister on your foot and it is worth noting that no one is immune - everyone gets a blister from time to time.

Moisture
This can come from perspiration or sweat which can build up if you are wearing cotton/non-wicking socks and non-vented shoes. Remember you have approx 125,000 sweat glands in your feet.

Dampness from walking in the rain, walking through wet grass etc can wet your socks and shoes. This can cause your foot to slide around inside your shoes.

The moisture is absorbed by the skin which makes the skin layers softer and tender (think how the skin on your toes and fingers goes all crinkly and soft if you sit too long in the bath!) therefore it becomes more likely to stick and rub against your socks and shoes.


Heat
When the skin on your feet gets hot, it again becomes softened and is more likely to react to any roughness.


Friction
Friction is triggered when two surfaces rub against each other so check out your socks and shoes; make sure they both fit properly.



Blisters can be caused by wearing socks that are too small or socks that are too big and bunch up under your foot or ones that are made of a harsh material.

Badly-fitting shoes cause friction between the foot and the shoes. Shoes that are too big or too small can make your foot to move around too freely, or persistently bang into the side of your shoe. To get the best out of your shoe or boot it needs to fit snugly so that it moves exactly as your foot does.

This is the easiest to remedy but easiest to overlook - when dirt or girt gets into your footwear - this causes friction.

Wearing no socks at all can also cause problems even in walking sandals.

The best thing to do is to try to prevent blisters by keeping your feet relatively dry and friction-free.


A blister is an area of raised skin with a watery liquid inside