Overview

Blood blisters are small pockets of blood that form beneath the skin’s surface when blood vessels are damaged without the skin breaking open. They appear as raised, fluid-filled lesions with a dark red or purplish color due to the trapped blood. Blood blisters are common and usually occur due to friction, trauma, or pressure, often affecting areas like the hands, feet, or inside the mouth. While generally harmless, blood blisters can cause discomfort and, in rare cases, may be a sign of an underlying health issue requiring medical attention.

Causes

Blood blisters are caused by injury or irritation that damages small blood vessels under the skin while leaving the surface intact. Common causes include:

• Friction: Continuous rubbing or pressure, such as ill-fitting shoes causing foot blisters.
• Pinching injuries: Skin caught in doors or tools can rupture blood vessels without breaking the skin.
• Burns: Minor burns, including sunburn or contact with hot objects, can lead to blistering with trapped blood.
• Allergic reactions: Allergic dermatitis can sometimes cause blistering in sensitive individuals.
• Certain medical conditions: Diseases like pemphigus or thrombocytopenia may cause spontaneous blistering.
• Sport injuries: Athletes commonly develop blood blisters from repetitive friction or impact during training or competition.
• Mouth trauma: Accidental cheek or tongue biting can cause blood blisters inside the mouth.

Symptoms

The main symptom of a blood blister is a raised bump on the skin filled with dark red or purplish fluid. Other common symptoms include:

• Swelling: Mild to moderate swelling around the blistered area.
• Pain or tenderness: The affected area is often sensitive to touch or pressure.
• Warmth: The skin around the blister may feel warm due to inflammation.
• No open wound: Unlike cuts or abrasions, the skin remains intact over the blister.
• Itching: Some blood blisters may cause mild itching as they heal.

Diagnosis

Diagnosis of blood blisters is typically straightforward and based on physical appearance. In most cases, no special tests are needed:

• Physical examination: A healthcare provider will inspect the blister’s color, size, and location.
• Patient history: Questions about recent injuries, friction, or medical history help determine the cause.
• Additional testing (if needed): In rare cases with recurrent or unexplained blisters, blood tests or skin biopsies may be performed to rule out underlying health conditions.

Treatment

Most blood blisters heal on their own without medical treatment. General care and home remedies can speed up recovery:

• Leave it intact: Avoid popping or draining the blister to prevent infection and allow natural healing.
• Protect the area: Use bandages or protective padding to prevent further irritation or friction.
• Cold compress: Applying a cold pack reduces swelling and pain in the early stages.
• Pain relief: Over-the-counter pain relievers like ibuprofen can help reduce discomfort and inflammation.
• Cleanliness: Keep the area clean and dry to avoid infection.
• Medical intervention: Large, painful, or infected blisters may require professional drainage or antibiotic treatment.

Prognosis

The prognosis for blood blisters is excellent. Most resolve within a few days to two weeks without any complications. Once the body reabsorbs the trapped blood, the blister dries up, and new skin forms underneath.

In rare cases, complications such as infection can occur, especially if the blister is punctured or exposed to bacteria. Prompt wound care minimizes this risk. Recurrent or unexplained blood blisters may indicate an underlying medical condition, and a healthcare provider should be consulted for further evaluation. Overall, with proper care, full recovery is expected, and long-term effects are uncommon.