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Accidental biting
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Dental procedures
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Sharp or poorly fitting dental appliances
In some cases, blood blisters may appear more easily in people with:
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Thin or fragile skin
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Circulation issues
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Diabetes
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Certain blood or clotting disorders
Symptoms to Expect
A blood blister may cause:
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A raised, bubble-like area under the skin
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Dark red, purple, or black coloring
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Tenderness or pressure pain
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Occasional swelling around the area
Most blood blisters are not dangerous and heal on their own within one to two weeks.

Should You Pop a Blood Blister?
In most cases, no. The intact skin over a blood blister acts as a natural barrier against infection. Popping it increases the risk of bacteria entering the wound and can slow healing.
If a blood blister bursts on its own:
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Gently clean the area with soap and water
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Apply an antiseptic
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Cover with a sterile bandage
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Keep the area clean and dry
How to Treat a Blood Blister at Home
For uncomplicated blood blisters:
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Reduce pressure or friction on the area
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Apply a cold compress for 10–15 minutes to reduce swelling
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Keep the blister clean and protected
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Wear properly fitting footwear or gloves if needed