View source for Blood blister

{{Short description|Injury of subdermal tissues and blood vessels where damage does not pierce the skin}}
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{{Infobox medical condition (new)
| name            = Blood blister
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| image           = Blood blister close-up 2 by Esinam.jpg
| caption         = On palm of [[right hand]]
| field           = [[Dermatology]]
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| duration        =  
| causes          =  [[Accident]]
| risks           = 
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[[File:Blood Blister - Right Foot.jpg|thumb|200px|Large blood blister on right foot]]

A '''blood blister''' is a type of [[blister]] that forms when subdermal [[tissue (biology)|tissue]]s and [[blood vessel]]s are damaged without piercing the [[skin]]. It consists of a pool of [[lymph]], blood and other body fluids trapped beneath the skin. If punctured, it suppurates a dark  fluid. Sometimes the fluids are cut off from the rest of the body and dry up, leaving behind dead cell material inside the blister with a texture like [[putty]]. Some blood blisters can be extremely painful due to bruising where the blister occurred.

There are also blood blister-like [[aneurysm]]s. These are sometimes located in the supraclinoid [[internal carotid artery]], and have been recognized as having unique pathological and clinical features.

== Causes ==
Blood blisters are commonly caused by accidents in which the skin is pinched by a tool, mechanism, or heavy weight without protective equipment. Blood blisters can also arise from forcible human contact, including grappling. 

Blood blisters also may occur with friction caused by constant rubbing of skin against a surface. Ill-fitting shoes that rub on the skin can cause the blood vessels in the skin to break and form a blood clot under the skin, resulting in a blood blister. Certain sports activities that require repeated movement and rubbing of the skin against equipment may also cause this; baseball pitchers, rowers, and drummers often contract blood blisters on the fingers and palms. They also form as a result of [[frostbite]].

Blood blisters can also occur in the mouth for a variety of reasons including side effects to certain medications, nutritional deficiencies, and mouth injuries.<ref>{{cite web|url=http://www.newhealthadvisor.com/Blood-Blisters-in-Mouth.html|title=What Causes Blood Blister to Occur in Mouth? What to Do?|date=19 November 2015}}</ref><ref>{{cite web|url=https://www.reference.com/health/blood-blister-tongue-7c4b93d00771b099|title=What Is a Blood Blister on the Tongue?|access-date=2016-11-06|archive-date=2018-12-14|archive-url=https://web.archive.org/web/20181214082435/https://www.reference.com/health/blood-blister-tongue-7c4b93d00771b099|url-status=dead}}</ref>

== Treatment ==

There are several methods of healing blood blisters, including [[Elevation (kinesiology)|elevation]] of the wound combined with application of a [[Cold compression therapy|cold pack]], and application of padded [[Dressing (medical)|dressing]]s or [[Splint (medicine)|splints]].<ref name="umb">{{cite web | url = http://www.utahmountainbiking.com/firstaid/blister.htm | title = Blisters | work = Ultra Mountain Biking | access-date = 2007-11-24}}</ref>

== See also ==
* {{annotated link|Bleeding}}
* {{annotated link|Blister}}
* {{annotated link|Bruise}}
* {{annotated link|Cherry angioma}}

== References ==
{{Commons category|Blood blisters}}
{{reflist}}
{{General injuries}}

[[Category:Skin conditions resulting from physical factors]]