Blood Blister in Mouth: Causes and Treatments

Published on: May 30, 2023
A man feeling pain and discomfort due to a blood blister in his mouth.

Blisters are fluid-filled sacks that can occur on the skin, sometimes filled with blood, which is known as a blood blister. These can occur anywhere, usually when there is friction against the skin, including a blood blister in mouth. What causes blood blisters in the mouth? Here is what you need to know.

Blisters form when the skin is damaged, usually from rubbing against something. Most blisters fill with a clear fluid, but if a blood vessel breaks, it can fill the blister with blood. These blisters can range from a tiny pinpoint to larger than a dime, usually red, purple, or almost black in color.

Unlike blood blisters that form on your hands or feet from rubbing against an object, oral blood blisters are usually caused by trauma or internal condition. If you have a sudden blood blister in your mouth, no pain, and no obvious injury, there may be a few possible causes of this blister.

What Causes Blood Blisters in the Mouth?

Trauma is the most common cause of a blood blister. If you bite your cheek or tongue, it can cause a blood blister to form. Hot or sharp foods can also damage the skin inside the mouth, or you may experience a blood blister on the tongue when an injury occurs.

If you have a blood blister in the mouth, it may also appear suddenly without pain or other symptoms. You may notice the blister when looking inside your mouth, you may get a blood blister on tongue, or you may feel the blister with your tongue inside your mouth. Some possible causes include:

  • Low platelets. Thrombocytopenia or low platelet count can cause blood blisters in the mouth. Pregnancy, certain medications, or an immune system response can result in low platelets which can cause oral blood blisters.
  • Allergic reaction. There are allergens and substances that can result in blistering inside the mouth that can fill with blood. Citrus, cinnamon, an astringent, and other acidic substances can result in the formation of oral blood blisters.
  • Radiation. Chemotherapy and exposure to radiation can cause blood blisters in the mouth.
  • Angina bullosa hemorrhagica. If you have painful blood blisters suddenly form, then burst a few minutes later, you may have angina bullosa hemorrhagica. This is a rare condition that only affects an estimated .05% of the population.

It is important to recognize whether a blister inside the mouth is a blood blister or other type of oral sore. Canker sores and fever blisters can also appear in the mouth, but they are usually not the same color and do not have blood inside the blisters or sores.

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Treatment for Blood Blister in Mouth

Blood blisters inside the mouth usually occur on the tongue, inside the cheek, or along the smooth oral surfaces. In many cases, these blisters are not painful, and they can quickly heal on their own. In most cases, no treatment is needed for an oral blood blister that does not cause complications.

Blood blisters will usually go away on their own. You can use OTC pain medications or ice if the blister causes any pain. You should not try to pop the blister – it will release the blood on its own and you can risk infections if you pop the blister prematurely.

When to See a Doctor or Dentist for an Oral Blood Blister

If you have a blood blister in your mouth that is extremely large or painful, you may want to visit your doctor or dentist. Any sore that does not heal in your mouth should be evaluated by a doctor. While most oral blood blisters are benign and not harmful, you may want to visit a doctor if:

  • You have recurrent blood blisters inside your mouth
  • The blister is very painful and interfering with your daily activities
  • A blood blister in mouth is so large it makes it hard to breathe or swallow
  • An oral blood blister does not heal within 1-2 weeks
  • There are signs of infection, such as pus or redness

If you have complications with oral blood blisters, your doctor can examine your sore and check for other possible health concerns. Medications may be prescribed if there is an infection, or to relieve painful blisters. In rare circumstances, you may need a biopsy if the sore is possibly malignant.
A young woman with pain caused by a blister in her mouth.
Most blood blisters on the tongue or inside the mouth are caused by trauma and will go away on their own. However, when a blood blister appears for no apparent reason or causes complications, you may want to visit your dentist or doctor to have it examined and receive treatment for your blister.

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