Foods That Cause Mouth Ulcers

Mouth ulcers are small sores that form on your gums, lips, inner cheeks or palate (roof of mouth).  Mouth ulcers aren’t contagious and mostly harmless. However, anyone who’s had one knows how unpleasant they are.

They can be triggered by several different factors, including minor injuries, anxiety, stress, biting the inside of your cheek, smoking and hormonal changes. What you eat is a huge contributor as well. Mouth ulcers aren’t contagious — and they go away on their own — but there are treatments to help ease pain and discomfort.

Mouth ulcers are different from cold sores. Mouth ulcers form inside your mouth due to irritation, injury, vitamin deficiencies or other factors. Cold sores, on the other hand, appear on your lips and are caused by a virus. Mouth ulcers aren’t contagious, but cold sores are.

If you experience frequent mouth sores and they are not going away, this may have to do with your diet. It’s important to visit a dentist that knows how to identify the source of your canker sore problem and offer fast treatment. This way, you can get some professional advice that is also personalized to you.

In the meantime, read on to find out what major foods can cause mouth ulcers.

Acidic fruits

Fruits that are acidic, or particularly citrusy, can cause your mouth to break out in ulcers. Pineapples, oranges, lemons, and limes are some examples of fruits with high acidity. Strawberries, in particular, tend to cause mouth irritation.

These fruits cause mouth tissue stress and can aggravate your gums. This is especially true if you already have a sensitive mouth. Any juices made with these fruits will also have the same effect.

Bananas, watermelon, and apples are good fruits to eat – you will avoid abrasion.


As nutritious as nuts are, they are surprisingly bad for your teeth. Nuts such as walnuts, peanuts, cashews, and almonds are dangerous territory for your gnashers. It is the amino acid L-Arginine in these nuts that contributes to canker sores.

Salted nuts are especially bad, as the sodium dries your mouth out and cause the lining to become slightly inflamed.


Deal breaker! Chocolate, unfortunately, is a top food that causes mouth ulcers. This is mainly because of an alkaloid in chocolate called the obromide. The mouth is quite sensitive to this ingredient and it can lead to something similar to an allergic reaction. Some people who have this mild allergy will develop canker sores on their tongue and/or inner cheeks.

You don’t have to cut out chocolate completely, but if it causes you pain in your mouth, then consider cutting down on the cocoa.

Spicy Foods

Spicy foods can disrupt the lining inside your mouth, causing an ulcer. A bit like acidic fruits, spicy foods have high acidity and therefore are more likely to distress the skin.

You’ll want to avoid foods like curries, hot sauce, jalapenos, and spicy chips to save yourself from oral pain. Most of these are a double whammy, as they tend to have high salt content as well.

Hard Foods

This is quite a broad range of foods. Yet, it is foods classified as “hard” that are abrasive, sharp, and sore-forming:

  • Raw vegetables
  • Toast
  • Potato chips
  • Pretzels

It’s best to avoid these when you can if you’re prone to canker sores.

Alternatively, eat these in smaller sized mouthfuls. You could also combine the foods with something that takes the dry and hardness away. Applying extra butter to toast, and having raw vegetables or potato chips with dip may help your mouth cope better.

Foods You Are Allergic To

We briefly mentioned chocolate allergies. If there is a certain food that is giving you mouth ulcers time and time again, you may be allergic.

Try and note down what foods trigger your mouth ulcers. Experiment with the foods you eat each week, cutting back on certain items and increasing your dosage of others. This way, you can figure out what ingredients are the most harmful.

If you’re in pain from eating a small quantity of a certain food, then see a doctor for allergy testing.


Dairy products such as milk, cheese, and yogurt are all common contributors to canker sores. Some doctors think that there is an ingredient in cow milk proteins that links to mouth ulcers. A flare-up could be due to an adverse immune reaction to cow’s milk.

If your mouth sores are recurring, it is definitely worth cutting out dairy products, especially those containing animal milk. Opt for soy and oat milk-based products and vegan cheese and see if these changes make a difference.

Coffee and Alcohol

There are certain drinks that, if consumed, bring a risk of oral ulcers. Coffee and alcohol (preferably not together!) are both very acidic. These are both drinks we often take in large quantities, and we’re least likely to give these up. It might be necessary to decrease your dose if you’re experience chronic mouth pain as a result.

The Food You’re Not Eating

Now, let’s shift the focus away from the foods you should avoid to foods you should pay attention to!

People get mouth ulcers if they are lacking certain vitamins and minerals in their diet. If your body is low on zinc, iron, B12 and/or folate then there’s a high chance you will get recurring sores.

To boost your levels of these, get more of these foods in your diet:

  • Zinc: oysters, whole grains and legumes
  • B12: meat, nutritional yeast, and yeast extract, and fortified cereals
  • Iron: dried fruit, green vegetables, red meat, beans and lentils
  • Folate: bread, rice, chickpeas, beans, and fresh fruit and vegetables


As you can see, there are many items that cause mouth ulcers and irritate the tissue. It’s best to eat these foods in moderation. Cut down on the foods that contribute to canker sores; you don’t have to ban them entirely.

However, if you do find that you have an underlying allergy it is best to cut those foods out altogether. Make sure you’re getting all the nutrients you need too. Like we said it’s not always about what your eating, but what you’re not eating that causes problems.

If you have altered your diet to eradicate your mouth ulcers, but they are still recurring, schedule an appointment with your Milpitas, CA dentist Dr. Beedu today.

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