Blood Blister In The Mouth

Sometimes you wake up in the morning and notice a black dot inside your mouth. You look closely into the mirror and notice that it looks like a blood-filled blister. Is it a serious problem?

It may be the first time you notice it, or it may have come and go for a few times before. Most likely the blood blister is caused by break of small blood vessels (capillaries) on the inner side of the mouth. If the bleeding continue, the lesion may enlarge. When the bleeding stops, the lesion will usually disappear within few days time. There may be slight pain or no pain at all.

       blood blister at inner cheek

This condition is usually benign, and is said to caused by minor trauma or injury to the oral mucosa. The trauma can be from chewing hard food, hot food, dentistry, brushing teeth, oral treatment, accidental self-biting during sleep etc. This condition is also called "angina bullosa hemorrhagica".

Nevertheless, you need to rule out whether you bleed abnormally easily or not. You need to check whether you have blood blisters elsewhere in the body other than inside the mouth. If you have easy bruising, easy bleeding from gum or nose and your wound is slow to clot after injury, you might need to check your blood for platelet count and coagulation profile. Low platelet (thrombocytopenia) can cause easy bleeding, which is not very uncommon.

Sometimes the blood blister could be "pyogenic granuloma", which is actually a bunch of abnormal capillaries present as a red nodule and can bleed easily. Compare to angina bullosa hemorrhagica, pyogenic granuloma can occur on the skin all over the body. Its size can be large and may not heal even within weeks. Pyogenic granuloma is more common in children while angina bullosa hemorrhagica is more common in older adult. 

       pyogenic granuloma

If the blood blister in your mouth come and go within few days, and you don't have any other problems such as fever or easy bleeding elsewhere, then it is probably angina bullosa hemorrhagica and is completely benign. If you are still worry, you should see a doctor and perhaps check your platelet and coagulation profile.