Blisters form when friction, force or other factors separate the top layer of skin from the inner layers and the resulting space fills with clear fluid or blood, according to Sports Injury Clinic. Wart treatments, medication injections, brown spider bites or pinching or crushing injuries to the toe or finger can cause blood blisters. Small blisters respond well to self-care measures, but medical attention is necessary if a blister is large or becomes infected.
Protection
If the blood blister is small and the skin is unbroken, it is likely to heal on its own if protected from further injury. Covering the area with a sterile gauze square and applying a bandage over it protects the blister. If a scab forms, as occurs after a liquid nitrogen treatment for warts, it will fall off spontaneously, according to the University of Wisconsin School of Medicine. Diabetics should contact a health care provider about any blister occurring on the foot, as serious infections can develop due to poor circulation and sensation.
Cleansing
If the blister breaks, organisms can enter the skin and cause an infection. If the open area is fairly small, it needs to be cleaned with soap and water and covered with a sterile bandage. A blood blister from a brown spider bite will expand until it ruptures, causing an open sore that should be cleaned daily with a povidone-iodine solution and soaked three times a day in saline--sterile salt water--to prevent infection, according to the Merck Manuals Online Medical Library.
Draining
A very large blood blister or one that is likely to break due to continued friction, the health care provider may decide to drain it. After numbing the area, the provider uses a sterile scalpel or needle to puncture the lower edge of the blister, expresses the fluid and covers it with a sterile bandage, according to the AMA. If medical attention is not available, the individual should not attempt to drain the blood blister herself.
References
- "Handbook of First Aid and Emergency Care;" American Medical Association; 2009
- Merck Manuals Online Medical Library: Spider Bites
- Sports Injury Clinic: Blisters - Treatment and Prevention
- UWHealth: Liquid Nitrogen Treatment
