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A blood blister in the mouth can be uncomfortable and unsightly. The terms blood blisters, mouth ulcers and sores can be used interchangeably, but each has different symptoms and different causes. However, once diagnosed, these blisters can be treated.
A blood blister is a type of mouth ulcer that is not caused by an infection. These sores are not contagious. They can occur anywhere in the mouth, such as the lips, cheeks, tongue or palate.
Possible causes of blood blisters include:
Blood blisters are commonly mistaken cold sores. Cold sores, also known as oral herpes, are caused by the herpes simplex virus 1 (HSV-1). These blisters most often occur around the mouth but can appear inside as well.
This virus is mainly acquired through saliva via casual contact, such as through a kiss or sharing a drink. Oral herpes is not considered a sexually transmitted disease. However, if a cold sore is present, avoid oral sex since this virus can sometimes be transmitted to the genitals during oral sex.
Cold sores begin as fluid-filled blisters that ultimately break open, leak a clear fluid and crust over. They are typically red and painful. Cold sores can heal without treatment within about 2 weeks.
Cold sores can be diagnosed through an oral herpes test. This blood-based test is often ordered as part of an online STD testing panel.
There is no test for other types of mouth sores and canker sores.
Most mouth sores will heal without treatment. Contact a doctor for persistent mouth sores that won’t heal.
For those with recurrent cold sores, antiviral medication can prevent outbreaks and reduce the severity of symptoms.