Blood Blisters: What You Need to Know
This morning, my daughter woke up unable to put her foot down. A dark, swollen spot covered part of her sole, and the pain made her wince with every step. At first, I thought it might be a minor injury—but the size, color, and tenderness made me pause. Could it be something simple—or a sign of a deeper problem?
Often, what we’re seeing is a blood blister: a purplish or dark red bubble beneath the skin that seems to appear out of nowhere. While usually harmless, blood blisters can be painful, limit movement, and occasionally signal an underlying condition. Understanding them helps ensure proper healing—and knowing when to seek medical attention.
What Is a Blood Blister?
A blood blister forms when tiny blood vessels (capillaries) beneath the skin break, while the outer layer remains intact. The trapped blood creates a raised, dark-colored spot. Common locations include:
Fingers and palms
Toes and soles of the feet
Inside the mouth (cheeks, tongue, gums)
Common Causes
Blood blisters often result from sudden trauma or repeated friction, such as:
Slamming a finger in a door
Wearing tight or ill-fitting shoes
Using tools or sports equipment without padding
Repetitive pressure on the skin
Oral blood blisters may appear due to:
Accidental biting
Dental work
Sharp dental appliances
Some people may be more prone due to:
Fragile or thin skin
Circulation issues
Diabetes
Blood or clotting disorders
Symptoms to Watch For
Typical signs include:
Raised, bubble-like swelling under the skin
Dark red, maroon, or black coloring
Pain or tenderness when touched
Occasional surrounding swelling
Most blood blisters heal naturally within 1–2 weeks.
Should You Pop a Blood Blister?
Generally, no. The skin covering the blister acts as a natural barrier against infection. Popping it can slow healing and introduce bacteria.
If the blister bursts naturally:
Clean gently with soap and water
Apply an antiseptic
Cover with a sterile bandage
Keep the area dry and clean
Home Care
Reduce friction or pressure on the area
Apply a cold compress for 10–15 minutes to ease swelling
Protect the area with padding or proper footwear
Avoid harsh chemicals or home remedies
For mouth blisters, rinse with warm salt water and avoid hot, spicy, or hard foods until healing occurs. Frequent or unexplained oral blisters should prompt a medical or dental consultation.
When to See a Doctor
Seek professional advice if:
The blister grows rapidly or becomes very painful
Signs of infection appear (redness, warmth, pus, fever)
Blisters recur without injury
You have diabetes, poor circulation, or clotting disorders
Healing takes longer than two weeks
Rarely, repeated or unexplained blood blisters may indicate a more serious condition.
Prevention Tips
Wear properly fitting shoes and protective gloves
Cushion sports equipment or tools
Keep skin moisturized to prevent cracking
Manage underlying health conditions
Conclusion
A sudden, dark blister on the foot can be alarming, but most blood blisters are minor injuries caused by friction or pressure and heal on their own. Observation, gentle care, and proper footwear usually suffice. However, if the blister is unusually painful, recurrent, or slow to heal, consulting a healthcare professional ensures nothing more serious is going on.