Question: How do you get blisters?

Alex Haragan answered on 8 Jun 2018:

Blisters are a protective mechanism used by the body to help when it has been damaged. Blisters really only occur in the skin (similar things can happen inside the body though).
Mostly they occur because of friction (rubbing of the skin, say the inside of your boots on a long walk) but can occur in response to any damage – such as freezing, burning, infections, certain chemical agents etc.
What happens it the damage results in the area needing repair. Part of this process is to get more blood cells to the area – so blood vessels and cells become “leaky” – meaning you get the build-up of fluid inside it. The fluid is typically similar to what makes up blood, but without the red blood cells, so it looks clear.
It can also be blood filled (blood blister) or become infected – so it goes yellow (pus).
Most people probably get it from rubbing – so if you going on a long bike-ride wear gloves, or a long hike wear thick socks and properly fitting boots!