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Canker sores can seem to suddenly appear for no reason. One minute your mouth is fine, and the next you have an annoying, sometimes painful lesion on your gums or cheek. While canker sores usually heal without treatment from a dentist or doctor, taking steps to help prevent them from developing can save you from the lingering discomfort they often cause. The key to stopping canker sores is to figure out what may trigger them in your mouth.

Is This Bump a Canker Sore?

Before investigating how to prevent canker sores, it’s worth checking to see if your self-diagnosis of that sore in your mouth is really correct. Several different types of lesions affect the oral cavity, including cold sores (also called fever blisters or herpes simplex), oral thrush and leukoplakia. A canker sore is a small, round or oval sore or swelling inside the mouth, often with a red edge and white or yellow centre. The most common sites for the sores to appear are inside the lips and cheeks, on the tongue, at the base of the gums and on the roof of the mouth.

Canker sores, also known as aphthous stomatitis, can also include large sores and clusters of tiny, irregularly shaped spots called herpetiform canker sores, writes Merck Manual. A dentist or doctor can diagnose a canker sore if you’re unsure or if the sore doesn’t heal after two weeks.

What Causes Canker Sores?

There is no single culprit behind canker sores, but they can be caused by oral trauma such as a cheek bite or even flare up in times of stress. Acidic foods such as citrus, strawberries, tomatoes, coffee and chocolate can also cause canker sores in some people, as can a vitamin deficiency, writes Michigan Medicine.

Several systemic diseases can also result in recurring mouth sores. The Cleveland Clinic notes that HIV, lupus, inflammatory bowel disease and celiac disease can all be associated with this symptom, so talk to your doctor if you suffer from mouth sores that won’t go away.

How to Prevent Canker Sores

The best way to prevent canker sores from developing is to try to identify what’s causing them. For example, did your dentures or a fork scrape your gum, or were you eating spicy or sharp, crunchy food the day before a sore appeared? Michigan Medicine makes several recommendations to help prevent canker sores:

  • Chew carefully and slowly and try not to eat and speak at the same time.
  • Avoid trigger foods like tomatoes, citrus fruits, potato chips, corn chips and hard bread crusts.
  • Brush your teeth twice per day using a soft-bristled toothbrush and floss once per day.
  • Find healthy ways to relieve stress such as meditation and exercise.
  • If you think your diet might lack vitamins and minerals, eat foods high in iron, folic acid, vitamin B12 and zinc. You should also limit or eliminate alcohol and tobacco use.

If another sore does appear, rinse with an antibacterial mouthwash such as for a soothing rinse to promote the natural healing of minor mouth irritations.

Although canker sores aren’t serious, they can be irritating and painful. Talk to both your doctor and dentist about any sudden changes in your mouth to keep your whole body healthy.