Four common causes of ulcers in the mouth—plus, how to get rid of them

Experts explain what causes ulcers in the mouth, plus the best natural preventative methods

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Ulcers—they’re pesky, they’re painful, and they make it hard to eat and smile. Most people have experienced these frustrating sores, but what exactly causes ulcers in the mouth? 

Ulcers can rear their ugly heads at the worst times. But, the good news is there are simple ways to treat mouth ulcers and natural preventative methods to beat recurring ulcers. To help you understand what's causing your mouth ulcers and how to get rid of them, we spoke to oral care experts. From investing in the best electric toothbrush and practicing good dental hygiene, to taking immunity supplements that combat nutrient deficiencies, here's everything you need to know about ulcers in the mouth—and how to prevent them from coming back.  

What are mouth ulcers?

Have you ever bitten down way too hard on your tongue, or accidentally chomped on the inside of your cheek while eating? That painful, bumpy mark that emerges in your mouth after the injury is a mouth ulcer, and they’re quite common. “Many people experience canker sores, also called mouth ulcers or aphthous ulcers, from time to time,” says Dr Rashmi Byakodi, of Best for Nutrition. “These are white-reddish, inflamed spots that form on the mucous membrane lining the mouth,” she continues. “Although they are painful, they typically heal on their own and don’t cause any problems.”

Think of a mouth ulcer as a skin injury you’d get on any other part of your body. When you get a paper cut, it hurts for a few days, but it eventually heals and poses no real threat to your overall health. That doesn’t mean ulcers aren’t a pain, though, and it's good to be clued up on how to treat them and prevent them from forming in the first place. 

What causes mouth ulcers?

1. Mouth trauma

Ulcers are typically the result of an injury. But how does someone injure the inside of their mouth? “Some form of trauma may cause the outbreak, including aggressive brushing, cheek or tongue biting, sports accidents, or injury to the mouth from dental treatment, braces, or ill-fitting dentures,” explains Dr Flora Stay, founder of Cleure.

2. Brushing your teeth

It might be surprising something as routine as brushing your teeth can cause mouth ulcers, too. "Sodium lauryl sulfate (SLS), a harsh detergent often found in toothpaste, can irritate the tissue in your mouth and cause ulcer outbreaks,” Dr Stay continues.

Also, if you brush your teeth aggressively, you might irritate the skin in your mouth, experience tongue pain, and cause an ulcer, too.

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3. Stress or hormonal factors

“Stress and hormonal changes during your menstrual cycle can both cause mouth ulcers,” says Dr Stay.

That’s right. Sometimes ulcers are just out of your control. The skin on the rest of your body can develop pimples and other marks due to stress or hormones, so it makes sense that the skin inside your mouth is subject to similar issues.

4. Nutrition deficiency

Ulcers can also be a result of a nutritional deficiency of vitamin B-12 or iron, Dr Stay tells us. If you get recurring ulcers, it might just be because you’re missing something in your diet.

It could even be that you’re consuming too much of a particular food.  Some people get ulcers from spicy foods, or foods that are rough in nature, like chips with sharp edges. It’s also possible for a mild food allergy to cause frequent mouth ulcers.

How to get rid of mouth ulcers

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Ulcers go away on their own, but they can be painful while they are there. There are a few home remedies you can try for some instant relief. 

To treat ulcers at home you can:

  • Use a cotton swab to dab a little bit of hydrogen peroxide onto the lesion.
  • Dissolve 1 tsp of salt or baking soda with 1/2 cup of warm water and rinse your mouth.
  • Suck on some ice chips or cubes and let them slowly melt over your sores.

All of these remedies should alleviate some pain. But if the home remedies aren’t cutting it, you might be able to find what you need at your local pharmacy.

“Most drug stores stock gels and ointments that can be applied to these painful sores,” says Dr Lawrence Ressler, dentist and gum specialist at Ressler Dental. “They coat the ulcers with a protective covering, and provide hours of needed relief.”

Five simple ways to prevent ulcers in the mouth

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There are so many factors that can cause mouth ulcers, so avoiding them completely often isn't an achievable goal. But, if you experience ulcers regularly and can’t pinpoint the reason why, it could have something to do with your lifestyle, habits, or medications. “It seems that things like stress, hormonal changes, spicy foods, vitamin deficiencies, or food allergies can bring them on,” Dr Ressler explains.

Try adjusting your diet or even the brand of oral care products you use if you're having issues with frequent ulcers.

Additionally, Dr Stay recommends that people who get frequent mouth ulcers should:

  • Avoid spicy and abrasive foods so as to not irritate the skin in your mouth.
  • Brush gently to avoid injuring your mouth.
  • Use a gentle sodium lauryl sulfate (SLS) free toothpaste.
  • Visit your dentist if your dentures are loose.
  • Cover sharp edges of braces with wax.

When to seek medical advice for mouth uclers

If you have tried all of the methods above and still experience recurring ulcers in the mouth, it might be time to see your doctor. While for some people, it's as easy as brushing more carefully or trying a new toothpaste, for others it can be tricky to nail down the cause. 

If you have any allergies or suspect an allergy is causing your mouth ulcers, speak to your doctor for advice. They will be able to help you pinpoint the root cause and determine the best treatment for you. 

w&h.com thanks Dr Rashmi Byakodi of Best for Nutrition, Dr Flora Stay of Cleure, and Dr Lawrence Ressler of Ressler Dental for their time and expertise.

Ciara McGinley
Ciara McGinley

Ciara is the digital health editor at woman&home.com, covering all things health & wellbeing from fitness to sleep to relationships. She's always on the lookout for new health trends, innovative fitness gadgets and must-read wellness books. 


Originally from Ireland, Ciara moved to London to study journalism. After graduation, Ciara started her career at Goodhousekeeping.com/uk where she worked as a junior digital writer before later becoming the acting senior digital writer. Her time there was spent writing lifestyle features, running photoshoots and video shoots, and organizing product tests (including sportswear and swimwear) for the website. 


Ciara qualified as a meditation teacher with the British School of Meditation in 2020, and outside of her day-to-day now runs her own meditation school called Finding Quiet. She is all about bettering that mind-body connection but believes wellness looks different to everyone. 


In her spare time, you’ll find her trying out new fitness classes, hiking up mountains, or in a beer garden because life is all about balance…