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What Are Canker and Mouth Sores?

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Medically Reviewed By Colgate Global Scientific Communications

Taking care of your dental health is not just about your teeth. Mouth sores can appear on your mouth, lips, or tongue, and while they usually quickly go away, they can be painful and cause concern. But don't worry, you're not alone! Mouth sores are quite common. Read on to find out what different types of mouth sores look like, including canker sores and cold sores, and how to treat each one of them.

What Are Mouth Sores?

According to the American Dental Association, mouth sores are oral lesions that can be caused by many things, including:

  • Irritation caused by a loose orthodontic wire, an ill-fitting denture, or a sharp edge from a broken tooth or filling
  • Infections from a fungus, bacteria, or virus
  • A specific disease or disorder

How Do I Know if I Have a Mouth Sore?

Broadly speaking, there are four types of mouth sores, and each one differs in cause and appearance:

  • Canker sores. According to the Mayo Clinic, most canker sores have a white or yellow center with a red border. They are typically round or oval. They form under your tongue, inside your cheeks or lips, or at the base of your gums. An early sign of infection is a tingling or burning sensation that you might notice a day before the sores appear. There are many types of canker sores, including minor, major, and herpetiform sores. So what causes canker sores? There can be many reasons, including dental work, food sensitivities, a diet lacking in vitamin B-12, zinc, folate (folic acid) or iron, or emotional stress.
  • Cold sores. The Mayo Clinic cites the herpes simplex virus strain HSV-1 as the cause of cold sores or fever blisters. It's recognized as groups of painful, fluid-filled blisters found near the lips or sometimes around the chin or under your nose. After the blisters break, a scab will form that lasts days. Once you're infected, the virus will stay in your body. While everyone's at risk for getting cold sores, you can experience complications from the virus if you have a weakened immune system caused by conditions like HIV/AIDS or atopic dermatitis, or cancer chemotherapy.
  • Leukoplakia. This condition is recognized by thick, whitish-colored patches found on the inside of the cheeks, gums, or under the tongue. It's often caused by ill-fitting dentures or tobacco use. Sometimes leukoplakia can be pre-cancerous, and your dentist may recommend a biopsy to investigate the patches.
  • Oral thrush. Also known as candidiasis, oral thrush is a fungal infection caused by Candida Albicans. While you might not notice signs of oral thrush at first, symptoms include creamy white lesions on your inner cheeks, tongue, or sometimes even on the roof of your mouth. The lesions have a cottage cheese-like texture, and they might even bleed a little when rubbed. Although oral thrush can affect anyone, they're more likely to occur in babies, older adults, or those with weaker immune systems.

How Are Mouth Sores Treated?

Each type of mouth sore requires a different kind of treatment:

  • Canker Sores. While canker sores usually heal on their own within a week or two, your doctor or dentist may prescribe a mouthrinse to reduce pain and inflammation as well as a topical ointment to provide some relief.
  • Cold Sores. While cold sores usually heal without treatment in two to four weeks, they can cause a lot of pain, which your dentist or physician can help you manage. Either of them can prescribe an antiviral medication that can help speed up the healing process.
  • Leukoplakia. For most people, removing the cause of leukoplakia is an effective treatment. So that might mean removing ill-fitting dentures or stopping tobacco use. If these lesions show early signs of cancer, the treatment plan will include eradicating the patches.
  • Candidiasis. According to the Mayo Clinic, any treatment's main goal is to stop the rapid spread of the fungus. While your specific treatment is heavily influenced by your age or general health, broadly speaking, your doctor will likely recommend an antifungal medicine.

How Can I Prevent Getting Mouth Sores in the Future?

Good oral health habits can go a long way! This includes brushing twice a day and flossing daily, as well as using a good mouthwash. Cutting out habits like tobacco use or excessive alcohol use can also help. Try to watch what you eat and cut out foods that irritate you or cause you any discomfort.

Mouth sores can be painful and frustrating, but they don't have to be impossible to manage! Now that you know how to recognize and treat them, you'll soon have a wide smile on your face again.


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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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