The blood will initially be red but turn darker as the days pass.
Blood blisters usually disappear on their own and pose no significant health concerns.
This article explains how to spot and treat a blood blister.
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What Is a Blood Blister?
The unbroken skin acts as a barrier to germs and can protect the underlying tissues from infection.
The blisters tend to be the same size and shape as friction blisters.
Verywell / Brianna Gilmartin
Those under 5 millimeters in diameter are calledvesicles, while larger blisters are calledbullae.
They do so as new skin grows over the injured tissues and the overlying skin is shed.
Examples include:
Diagnosis
Blood blisters can usually be diagnosed by appearance alone.
In many cases, youll be able to do so yourself and you wont need medical evaluation or treatment.
While unlikely, a blood blister may turn out to be something else entirely, like cancer.
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.
Abiopsyis critical to the diagnosis.
This is the only procedure that can definitively diagnose skin cancer and ensure the correct treatment.
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.
Over timeabout one to two weeksthe blister should dry up on its own.
With that said, large and painful blisters may need to be drained to relieve pain.
Blood blisters are easily treated and usually heal on their own without incident.
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