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Complex Canker Sores: What They Are and How They're Treated

Published date field Last Updated:

Medically Reviewed By Colgate Global Scientific Communications

Almost everyone's had a canker sore – you know, those annoying, painful little sores you get from eating too much acidic food or from accidentally biting the inside of your cheek.

But for some people, canker sores pose a critical problem. Complex canker sores – also known as major canker sores – can last for weeks, leave scars, and indicate a more serious health issue.

If you have a canker sore that's more than just a minor annoyance, it's best to educate yourself about complex canker sore symptoms, causes, risk factors, and treatment options.

Regular vs. Complex Canker Sores

Regular canker sores – also known as mouth ulcers – are definitely annoying and might make eating painful. But they usually heal by themselves in one to two weeks if not further aggravated. Found inside your mouth, they're typically small white or yellowish sores with a red border caused by stress, mouth abrasions, or acidic food.

Complex canker sores, according to the Cleveland Clinic, are much larger than regular sores. Plus, they can be severely painful – even debilitating – and make eating and drinking difficult. And complex canker sores can last up to six weeks.

If you have complex canker sores, you might also have other symptoms, such as fever, swollen lymph nodes, and sluggishness. Finding the cause of the sore can help you toward the path to healing.

Causes of Complex Canker Sores

The complex variety of canker sores is typically a symptom of an underlying health issue or disease. That's why if you have complex canker sores, we advise you to see your medical doctor immediately.

You might be at risk for complex canker sores if you have any of these conditions:

  • Autoimmune diseases (i.e., inflammatory bowel diseases, Celiac disease, Lupus, Behcet's disease)
  • Deficiencies in vitamins and minerals, such as iron, zinc, folic acid, or Vitamin B1, B2, B6, B12, or C
  • Allergies to certain foods or oral care products
  • Reactions to medications

Complex Canker Sore Treatment

Because they're usually a symptom of an underlying health condition, treating the condition is one way to treat complex canker sores. Once the health issue is under control, let's hope your canker sores go away.

During a complex canker sore outbreak, though, you might seek out some over-the-counter treatments to aid in pain reduction and the healing process. A study published in StatPearls and available on the National Center for Biotechnology Information site suggests trying one of the following treatments.

Analgesics (temporary anesthetic): Analgesics are numbing products containing medicines like benzocaine to help relieve the pain for a short time. Analgesics typically come in liquid and gel forms, which can be washed away by saliva. Just follow product package instructions on application frequency.

Occlusives: These protective films adhere to cover the sore and guard it during the healing process. They're available at most drugstores and typically last longer than analgesic medicines.

Antiseptics: With active ingredients like sodium bicarbonate (baking soda), chlorhexidine gluconate,  or hydrogen peroxide, antiseptics can speed healing by killing excess bacteria around the sore.

Nonsteroidal Anti-inflammatory Drugs: Taking over-the-counter pain relievers like ibuprofen or acetaminophen might alleviate the swelling and pain associated with canker sores. Make sure to follow package instructions and only take as directed.

If your canker sores are especially severe, your doctor might also suggest:

  • An antibiotic or another prescription medication to treat any accompanying infection.
  • A corticosteroid to reduce swelling and help heal your sores.

Since complex canker sores are usually the symptom of something more serious, it's important to make an appointment with your health care provider to explore and diagnose the true reasons for these sores. Don't let them disrupt your life. A treatment plan can help you with the pain and enhance healing, so the only thing you feel is relief.


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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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