A skin blister or, in Latin, bulla ("bladder", plural bullae ) is a fluid-filled space in dermatology that is at least the size of a pea (> 5 mm) above the skin level. Smaller fluid accumulations are called blisters ( vesicles or skin blisters hereinafter). A distinction is made between subcorneal (located under the horny layer ), intraepidermal (located in the epidermis ) and subdermal (located under the dermis ). Blisters are one of the primary efflorescences .
Bullous skin changes are often the result of chemical or physical noxious substances such as burns ( blisters ), second-degree frostbite or mechanical irritation, for example in the case of chafing shoes. The detachment of one or more layers of skin (mainly the cornea , epidermis and dermis ) as a result of one of the above-mentioned external influences creates a skin blister. This resulting cavity in the skin is filled with tissue fluid , which promotes wound healing and, to a certain extent, helps protect the injury. A bubble does not form immediately. It can take up to six hours. Also, infections (eg bullous erysipelas ) may show up in a bubble.
As a rule, the skin blister should not be pierced as the dilated skin protects the wound well. However, if the blister is under the sole of your foot, you can pierce it with a sterile needle to help it heal faster. The bladder should then be covered with a large plaster , such as a blister plaster , to prevent infection.