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How Blisters in Mouth Tissue Occur and How to Treat Them

Published date field Last Updated:

Medically Reviewed By Colgate Global Scientific Communications

It’s not unusual to suddenly find a blister in your mouth or on your gums. While they’re annoying and slightly painful, they usually go away on their own. In some cases, however, they can be contagious and might pose a greater risk of infection. Finding out what has caused the blisters is key. Read on to find out how blisters in mouth tissue occur and how to treat them.

What is a Mouth Blister?

Mouth blisters or sores are tiny lesions that appear on any of the soft tissues in your mouth, including the lips, inside of the cheeks, gums, tongue, and even the floor or roof of your mouth.

What Causes Blisters in the Mouth?

Several different things can cause blisters inside the mouth:

  • Tissue Trauma or Irritation. If you have a broken filling or sharp tooth, they can very easily cut into your mouth tissue, causing you to have a blister. Similarly, poorly fitted dentures or braces can cause a similar problem. A study in Trauma in Dentistry also notes that chronic biting of your cheeks or lips can cause lesions. Accidental biting of your lip or cheek might also cause a mouth blister.
  • Tissue Burn. The Trauma in Dentistry study points out that thermal burns in the mouth are highly prevalent amongst children and young patients. They’re caused by accidentally ingesting a hot liquid or food, resulting in blisters around the burnt area. While tissue burns aren’t usually severe, you should not contaminate the blisters while they heal.
  • Cold Sores. These are caused by the herpes simplex virus and are very contagious. Often, you’ll experience tenderness or a burning sensation before the actual sore appears. They will begin as blisters and then crust over. While the herpes virus can live in your body for years, it only appears as sores when it’s triggered by something else, such as stress, sun exposure, another illness, or hormonal changes like menstruation.
  • Canker Sores. Unlike cold sores, canker sores aren’t contagious. They can look like a pale or yellow ulcer appearing in your mouth with a red outer ring. You may see one or several of them. Unfortunately, we don't know the exact cause of canker sores. Still, they have several risk factors and triggers, including hormone changes, stress, a weakness in your immune system, or a lack of certain vitamins and minerals in your diet.

MedlinePlus also notes that while it’s less common, blisters in the mouth can also be a sign of:

  • Autoimmune disorders
  • Cancer of the mouth
  • Hand-foot-mouth disease
  • A weakened immune system caused by a disease like AIDS or if you’re taking medicine after a transplant

Treating Blisters in the Mouth

Most mouth blisters will often go away on their own in 10-14 days. Sometimes, however, they can last for several weeks. Here’s what you can do to get some relief:

  • Apply ice to the sore.
  • Avoid hot foods and beverages, spicy and salty foods, and anything that contains citrus.
  • Take over-the-counter pain relievers.

If you need help figuring out what’s triggering the blisters, don’t hesitate to contact your dentist or doctor. It’s also advisable to make an appointment to see them if:

  • You have a weakened immune system.
  • You have symptoms like a fever, skin rash, or difficulty swallowing.
  • Your blisters aren’t getting better or last longer than two weeks.
  • You have large white patches on your tongue or the roof of your mouth (this could be a sign of thrush).

Blisters in your mouth can make it difficult for you to enjoy your favorite foods. But sometimes, they might be more than just a little annoying; they can be a sign of a serious or contagious condition. Consult with your dentist or doctor, so you can get treatment and be pain-free as soon as possible!


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This article is intended to promote understanding of and knowledge about general oral health topics. It is not intended to be a substitute for professional advice, diagnosis or treatment. Always seek the advice of your dentist or other qualified healthcare provider with any questions you may have regarding a medical condition or treatment.

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