What Causes Blisters

Though our skin is an amazing protector against the elements, it can become damaged by such factors as heat, cold, friction, chemicals, light, electricity and radiation, all of which ‘burn’ the skin. A blister is the resulting injury that develops in the upper layers of the skin as a result of such burns.

The most common example of a blister, which we’ve no doubt all experienced at some time, is due to the repeated friction caused by the material of a pair of shoes rubbing against, and irritating, the skin. The resulting water blister is a kind of plasma-filled bubble that appears just below the top layers of your skin.

The plasma, or serum – which is a component of your blood – is released by the damaged tissue cells and fills the spaces between the layers of skin in order to cushion the underlying skin that is being rubbed and protect it from further damage. As more and more serum pours into the space, the skin begins to inflate under the pressure, forming a small balloon full of the serous liquid. Given time to heal, the skin will reabsorb the plasma after about 24 hours.

Similarly, a blood blister is a variation of the same injury where the skin has been forcefully pinched or crushed but not pierced, causing small bloodvessels to rupture, leaking blood into the skin. All blisters can be tender but should never be popped in order to drain the fluid as this leaves the underlying skin unprotected and also invites infection into the open wound.

Blister caused by second-degree burns

Skin – When any type of bum is experienced, the overlying skin expands as it receives the protective plasma/serum.

Damage – This particular example of a blister burn has caused damage to the keratinocytes in the skin. Second-degree burns are most often caused when the skin comes into contact with a hot surface, such as an iron or boiling water, or even after exposure to excessive sunlight.

Plasma – Serum is released by the damaged tissues into the upper skin layers to prevent further damage below in the epidermal layer. It also aids the healing process, which is why you should avoid popping your blisters.

Fluid reabsorbed – After a day or so the serum will be absorbed back into the body and the raised skin layers will dry out and flake off in their own time.