Definition of Blister
Blister: A collection of fluid underneath the top layer of
skin (epidermis). One that is more than 5 mm in diameter with thin
walls and is full of watery fluid is called a bulla or a bleb. There are many causes of blisters including burns, vesicant agents, friction
forces, and diseases of the skin.
There are a number of types of blisters, including:
- Blood blister -- a blister full of blood due to a pinch,
bruise or repeated friction.
- Water blister -- a blister with clear watery contents that
is not purulent (does not contain pus) and is not sanguineous (does
not contain blood).
- Fever blister -- a blister in the mouth or around it that
causes pain, burning, or itching before bursting and crusting over.
It is due to the herpes simplex virus which is latent (dormant in the
body) and can be reawakened (reactivated) by such factors as stress,
sunburn, or fever. Hence, it called a fever blister or a cold sore.
The word "blister" entered English in the 14th century. It came
from the Middle Dutch "bluyster", blister and was a modification of
the Old French "blostre" which meant a leprous nodule -- a rise in
the skin due to leprosy.
Last Editorial Review: 4/7/2004
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