A blood blister is a raised section of skin filled with blood. Possible causes include pinching the skin, lifting heavy weights, repeated rubbing, minor trauma, and more.
In many cases, blood blisters will go away after a short time and are little cause for concern.
In this article, we examine what blood blisters look like, what causes them, and what someone can and should do if they develop one.
Blood blisters appear as raised, fluid-filled sacks on the skin and look very similar to friction blisters.
Unlike friction blisters that contain a clear liquid, blood blisters contain a red fluid. The liquid begins as a light red color that becomes darker over time.
Most blood blisters will cause minor irritation at the site of the blister. A person may feel pain from the action that caused the blister to form in the first place.
Areas to likely to be affected
Blood blisters can form on the skin in different locations. Some of the most common places where blood blisters develop include:
- near joints
- near bony parts of the body
A blood blister can form anywhere on the body where the skin is pinched but does not break open. Closing a drawer on a finger or lifting heavy weights for prolonged periods can cause blood blisters.
Other causes may include:
- a tool or other object repeatedly rubbing against the skin
- poorly fitting shoes that pinch the skin
- sweaty feet that cause extra friction
- minor trauma from pinching the skin between two objects
- severe frostbite
Blood blisters in the mouth are often related to another condition. If someone has a blood blister in their mouth, they should see a doctor. Some causes of blood blisters in the mouth include:
- mouth cancer
- nutritional deficiencies
- excessive alcohol use
- bleeding disorders
It is possible for nearly anyone to get a blood blister. Preventing blood blisters involves people taking good care of their health and body and using appropriate protection in situations that require it.
People should take the following steps to reduce the risk of developing a blood blister:
- wear gloves when working with tools or lifting heavy weights
- wear appropriately sized footwear
- keep feet dry
Most blood blisters will heal on their own over the course of 1–2 weeks. People do not typically need to take any special actions to treat the blisters, except keeping the area with the blister clean.
Sometimes, a person may experience some extra problems, which may include the blister not clearing up on its own. Signs that a person may need to see a doctor include if:
- the blister repeatedly returns
- there is no apparent reason for the blister to have formed
- the blister is caused by an allergic reaction
- multiple unexplained blisters have formed
- there are symptoms of infection, such as red lines or warmth spreading from the blister
- blisters have formed in the mouth or eyelids
- The blister is making it difficult for a person to move their hands or walk
If a person believes that their blood blister warrants a visit to the doctor, the doctor will likely ask questions about what happened to cause the blood blister. In most cases, a simple examination is enough to identify a blood blister and diagnose any potential local infection.
In cases of chronic or unexplained blisters, a doctor may need to look at potential underlying causes of the blister. Some types of skin cancer appear similar to a blood blister.
A biopsy may be required if the doctor suspects that the blister is something more than a simple blood blister.
In many cases, a person does not need to do anything to treat a blood blister. The blister will naturally heal and dry up.
Doctors often recommend leaving the blister alone to let it heal on its own to avoid secondary infection of the blister.
Blood blisters that form on feet and toes may require additional steps to ensure they heal properly. A burst blister will be prone to infection.
Some general steps to take include:
- elevating and applying ice to the blister
- wrapping the blister loosely to help avoid additional friction
- avoiding putting pressure on the blister by removing shoes or wearing open-toe footwear.
- gently cleaning and protecting a blister that has burst open
- seeking medical attention when needed
There are also some things that are not recommended for blood blisters. People should avoid doing the following:
- wearing shoes that do not fit
- peeling away skin as it heals, as this could open up the wound to infection
- popping the blister
Some people recommend various natural cures, such as skin creams and natural herbs, to treat blood blisters. How well these home remedies work is not well researched or documented, however.
In general, it is recommended that people avoid popping a blood blister. Allowing it to heal on its own is the safest way to avoid complications, such as delayed healing and infection.
Blood blisters are very common and are not cause for concern. In most cases, the blister will heal with no further complications.
In rare cases, a blood blister may become infected, which will require additional treatment.
It is helpful to know what caused the blood blister in the first place. Working out the cause can help prevent blood blisters from forming in the same spot in the future.
If a person cannot explain the origin of the blood blister, they should visit their doctor as it may require additional medical intervention.