Struggling with a painful canker sore? Health's medical editor weighs in on how to prevent canker sores from developing in the first place (such as making changes to your diet), plus the best treatments for an existing canker sore.

By Roshini Rajapaksa, MD
Updated November 04, 2016
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Canker sores are frustrating and painful. If you find you're getting canker sores often, the solution may be as simple as avoiding spicy foods or acidic fruits, which can irritate the mouth. Also, try brushing and flossing right after meals to help remove food particles stuck between your teeth. And stop using any toothpastes or mouth rinses that contain sodium lauryl sulfate, a chemical that can be harsh on soft tissue, potentially causing canker sores.

If you have stubborn sores, you could be deficient in certain nutrients, such as folate, iron, or vitamin B12. Make sure you’re eating a well-balanced diet (you can get folate from beans and vegetables such as spinach and broccoli, and iron and B12 from tuna and eggs, among other foods). Consult your doctor if you think you need a supplement. Stress can also trigger the sores, so getting plenty of sleep and finding ways to tame tension may help prevent them. Less frequently, canker sores can be linked to conditions like inflammatory bowel disease (such as Crohn’s and ulcerative colitis) and HIV. So if lifestyle adjustments don’t make a difference, it’s worth seeing a doctor.

Notice a canker sore developing? Try gargling with salt water. You can also apply an over-the-counter topical ointment directly on the sore to ease pain. Usually canker sores hurt for only a few days and go away completely in a week or two. But if you have a severe, painful one, your doctor may prescribe a special mouth rinse or corticosteroid ointment.

Health’s medical editor, Roshini Rajapaksa, MD, is assistant professor of medicine at the NYU School of Medicine.