Blood Blister

What is a blood blister?

A blood blister is a type of blister filled with blood rather than clear fluid. Blisters are small pockets of liquid beneath the skin.

The skin consists of three layers: the epidermis (outermost layer), the dermis (middle layer), and the hypodermis (bottom layer). Blisters typically form beneath the epidermis and can be filled with clear fluid or blood, depending on the type of injury.

Blood blisters form when blood vessels in the skin are damaged. The body's immune system responds to the damage, causing inflammation, which leads to blister formation. Blood blisters commonly occur on the fingers, hands, toes, and feet, particularly around joints or bony areas like the balls of the feet and heels.

While most blood blisters on the skin heal on their own, those that develop inside or near the mouth, such as on the lips or inner cheeks, may indicate more serious underlying conditions and should be examined by a healthcare professional.

Symptoms

What does a blood blister look like?

A blood blister is an elevated pocket of skin, similar to a friction blister. However, due to the presence of blood rather than clear fluid, blood blisters can be red, black, or purple. Initially, they may appear light red but darken over time. Their size can vary.

Due to the injury that caused the blister, you may experience discomfort or pain in the affected area, and in some cases, the blister may feel itchy.

Causes

A blood blister forms when the skin is pinched or injured without breaking open. Instead of filling with clear fluid, blood from broken vessels collects in the area, damaging the lower layers of the skin. The blood accumulates, forming a blister to protect the skin and promote healing.

Blood blisters can occur from situations such as shutting a drawer on your finger or stubbing your toe. Friction from sweaty feet or ill-fitting shoes may also lead to blisters. Additionally, severe frostbite and certain medications, such as blood thinners, can contribute to blood blister formation.

A condition known as angina bullosa haemorrhagica may cause painful blood blisters to form in the mouth, particularly on the gums, tongue, and floor of the mouth. This non-cancerous condition usually resolves without treatment.

Blood blisters around or inside the mouth could be a sign of more serious health issues, including:

• Blood disorders
• Oral cancer
• Rheumatoid arthritis
• Kidney failure
• Diabetes
• Hypertension (high blood pressure)

Diagnosis and Tests

How are blood blisters diagnosed?

In most cases, blood blisters do not require medical attention. A healthcare provider can typically diagnose a blood blister based on its appearance, as there are no specific tests for this condition.

If you see a healthcare provider, they may examine the blister to ensure there is no infection. If the blister is in an unusual location, such as the eye, mouth, or genitals, a biopsy may be performed. This involves removing fluid from the blister for further testing.

Management and Treatment

How is a blood blister treated?

Most blood blisters heal on their own within a week. As new skin forms beneath the elevated blister, the blood dries, and the healing process begins. However, if you wish to speed up healing, you can follow these steps:

• Wash your hands and gently clean the blister with water and mild soap.
• Apply an antibacterial cream or ointment to the blister.
• Cover the blister with a bandage or gauze to protect it.

Change the bandage daily and ensure the blister remains clean and dry. Applying an ice pack can help alleviate pain, and over-the-counter pain relievers like paracetamol or ibuprofen may be helpful.

Do not attempt to pop the blister or peel the surrounding skin, as the skin covering the blood blister protects deeper layers from infection.

Prevention

How do I prevent a blood blister from forming?

Blood blisters typically occur when the skin is pinched, especially on the hands and feet. To reduce the risk of developing a blood blister, consider the following:

• Take care when using tools or objects that may pinch your skin.
• Wear gloves when handling tools like pliers or pruners.
• Protect your feet by wearing socks and well-fitting shoes.
• Use drying powder inside shoes to absorb moisture.
• Add padding to shoes if you feel pressure on your feet.

Outlook/Prognosis

What should I expect if I develop a blood blister?

Blood blisters usually heal within a week. During this time, keep the area clean, apply an antibacterial cream, and cover it with a bandage. Avoid wearing closed shoes if the blister is on your foot; opt for open-toe shoes to prevent further irritation. Contact a healthcare provider if you suspect the blister is infected.

Living With

When should I contact a healthcare provider?

Seek medical advice if the blood blister does not improve after a week or shows signs of infection. If infected, the skin around the blister will become swollen, red, and filled with pus (yellow, green, or white). Left untreated, an infected blister could lead to further complications, such as blood or skin infections.

Additionally, contact a healthcare provider if you experience any of the following:

• A very painful or recurring blood blister
• Multiple blood blisters without a clear cause
• A blood blister in unusual locations, such as the mouth, eyes, or genitals

A Note from MD.co.uk

Blood blisters are a common skin condition and, though they may be uncomfortable, they are typically not a cause for concern. A blood blister will generally heal on its own within a week. However, you should consult a healthcare professional if the blister appears to be infected or forms in an unusual location. While blood blisters can arise for various reasons, it is always wise to have them checked.