What Causes Blood Blisters and How Do You Get Rid of Them?

A blood blister occurs when tiny blood vessels are damaged beneath intact skin, often due to friction or pressure, resulting in a painful fluid-filled pocket. Most cases heal without intervention, but knowing their potential causes can help you avoid future discomfort and recognize when expert care is needed.

Overview of Blood Blisters

A blood blister forms when tiny blood vessels (called capillaries) are broken in subdermal tissues without breaking the skin. Subdermal tissues lie just beneath the middle layer of skin (called the dermis) and are rich in blood and lymph vessels.

Aggressively rubbing, pinching, or striking the skin can cause a blister as blood and lymph fluid create a pocket under the epidermis. Unbroken skin serves as a barrier against germs, protecting underlying tissues from infection.

The blood in the blister can turn from red to purple as the blood cells start to die and release oxygen. Hemoglobin, the protein that gives blood its color, turns bright red when oxygenated and purple when it is not.

As the fluid in the blister starts to dry up, the contents can become putty-like and the overlying skin can become hard and irregular.

Signs and Symptoms of a Blood Blister

Symptoms of a blood blister can vary depending on the underlying cause. The blisters tend to be the same size and shape as friction blisters. Those under 5 millimeters in diameter are called vesicles, while larger blisters are called bullae.

Symptoms of a blood blister may include:

• A firm, dome-shaped pocket of skin with blood inside
• Pain felt beneath and around the blister
• Redness around the perimeter of the blister
• Pressure or pain when the blister is touched or pressed

The size and location of a blood blister can tell a lot about the cause of a blister.

Blood blisters often appear on the hands, fingers, feet, toes, and bony areas like heels or the balls of your feet. They can also develop around or inside the mouth or lips. 

What Causes Blood Blisters to Form? 

While blood blisters can happen to anyone, they are common in active people (such as athletes or dancers) or people who work with their hands or spend a lot of time on their feet.

Common causes of blood blisters include:

• Slamming a finger with a hammer or in a closing door
• Wearing poorly fitted shoes that rub against your heels
• Wearing poor-fitting work gloves that rub against your fingers
• Performing heavy manual labor without gloves
• Lifting weights heavier than you are used to
• Participating in endurance sports, such as long-distance running

Taking anticoagulants (“blood thinners”) can further increase the risk of blood blisters.

More serious causes of blood blisters include:

• Severe frostbite: Blood blisters can form as the skin thaws and breaks underlying capillaries.
• Diabetes: Poorly controlled blood sugar can lead to the formation of blisters, called diabetic bullae, on the hands or feet.
• Kidney failure: End-stage kidney disease often manifests with blood blisters on the hands, feet, or face.
• Angina bullosa hemorrhagica: This is a rare condition of unknown origin that causes blood blisters around and inside the mouth.
• Rheumatoid arthritis: This autoimmune disease can cause vasculitis (blood vessel inflammation), sometimes causing blood blisters on the joints of the fingers.
• Leukocytoclastic vasculitis: This is a rare type of vasculitis affecting capillaries that causes multiple tiny blood blisters to appear, mainly on the legs and buttocks.

When to Visit a Healthcare Provider

Blood blisters typically heal on their own within a week. They do so as new skin grows over the injured tissues and the overlying skin is shed.

While most blood blisters are nothing to worry about, you should see a healthcare provider if you have unusual symptoms as this may be a sign of a serious medical condition.

Examples include:

• A blood blister appears for no known reason.
• Several blood blisters appear at once.
• The blood blister goes away, then comes back again.
• A blood blister appears on the gums, roof of the mouth, or throat.
• A blood blister gets progressively larger.
• A blood blister pops and then fails to heal.

Diagnostic Process

Blood blisters can usually be diagnosed by appearance alone. In many cases, you’ll be able to do so yourself, and you won’t need medical evaluation or treatment.

If there are any doubts about the cause of a blood blister, a healthcare provider can run tests to check for signs of infections, diabetes, or medical conditions like rheumatoid arthritis. This may involve blood tests or procedures like a biopsy for blisters that have an unusual appearance or are in unusual places, such as the brain, back, buttocks, or face.

While unlikely, a blood blister may turn out to be something else entirely, like cancer.

Blood Blister vs. Nodular Melanoma

Nodular melanoma, a type of aggressive skin cancer, is one condition often mistaken for a blood blister. This blood blister lookalike grows rapidly—typically over the course of several weeks or months—so it’s important to catch it as early as possible.

Unlike other forms of skin cancer, nodular melanomas are typically symmetrical, like a blister. They are often smooth like a blood blister, but can also be rougher and crusty. Nodular melanomas are often dark purplish, but they can also be flesh-toned.

A biopsy is critical to the diagnosis. This is the only procedure that can definitively diagnose skin cancer and ensure the correct treatment.

How to Get Rid of Blood Blisters

Most of the time, a blood blister will heal on its own as long as you protect it and avoid popping or draining it.

To treat a blood blister at home:

• Gently wash the blister with mild soap and water.
• Apply an antibacterial cream or ointment.
• Protect the blister by covering it with a bandage or gauze.
• Take an over-the-counter painkiller like Tylenol (acetaminophen) or Advil (ibuprofen) if there is significant pain.
• Apply an ice pack to the blister for 10 to 15 minutes several times a day to help ease the pain.
• Drink ice water or suck on crushed ice if there is a blister in your mouth.

Should You Pop or Drain a Blood Blister?

Though you may be tempted to pop a blood blister, experts recommend resisting the urge to do so. The layer of skin that covers the blister helps protect the underlying tissues from infection. The blister should dry up on its own in about one to two weeks.

With that said, large and painful blisters may need to be drained to relieve pain. This can be done by sterilizing a small needle with rubbing alcohol and gently piercing one edge of the blister to drain the fluid.

Afterward, wash the area with soap and water, apply antibacterial cream, and cover the blister with a bandage or gauze.

Prevention Tips

Accidents happen and, even with the best of care, blood blisters can still occur. But there are a few things you can do to decrease the risk:

• Wear heavy gloves if you work with your hands or use heavy equipment.
• Use glove liners to reduce friction when wearing rough or thick gloves.
• Make sure that your shoes fit you properly.
• Always wear socks. Thicker ones should be worn with boots or if you are on your feet a lot.
• Protect your heels with adhesive padding or moleskin until your shoes are broken in.
• Powder your shoes to reduce friction and absorb excess moisture in heavy boots or shoes.
• Moisturize your feet to reduce friction in your shoes or boots.