Are There Foods that Cause Mouth Sores?

Multiple factors cause mouth sores, including a variety of different foods. Learn more about them in this article.
Are There Foods that Cause Mouth Sores?
Mariel Mendoza

Written and verified by the doctor Mariel Mendoza.

Last update: 20 April, 2023

For a long time, the idea that certain foods cause mouth sores was widespread. However, these food aren’t actually direct triggers of this condition. What happens is that some increase one’s susceptibility to developing them, or tend to worsen the symptoms when they are already present. With that in mind, are you interested in knowing what they are?

First of all, it’s worth remembering that these sores are also called ‘aphthous ulcers’ or ‘mouth ulcers’. They are lesions of loss of continuity of the mucosa of the mouth. They are usually small, multiple, recurrent, and sometimes very painful.

Their exact cause isn’t established; however, they’re often associated with irritation caused by sharp teeth, dental appliances, consumption of very hot foods, and smoking. In addition, it has been determined that some foods tend to exacerbate them. Let’s take a closer look at what they are.

What are mouth sores?

Mouth sores are the loss or erosion of the delicate tissue that lines the mouth, also called mucous membrane. They are small, ulcer-like lesions with a reddened surrounding. At first, they look like a small vesicular lesion, which then ruptures early.

They usually cause pain, but most heal on their own within two weeks, leaving no sequelae. They sometimes start as reddish spots that progress to whitish spots and then to painful grayish ulcers. They are shallow and maintain a reddish, raised halo.

The lesion usually appears on the inner surface of the lips; it can also occur on the buccal mucosa, the floor of the mouth, or the soft palate.

Characteristically, in addition to pain, they cause increased sensitivity and even a burning sensation. When accompanied by fever, swollen lymph nodes, or cough, a possible infection should be suspected.

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Factors that can cause mouth sores

Although there’s no specific etiology known to cause mouth sores, there are factors that influence the precipitation or worsening of outbreaks. This encompasses the following:

  • Emotional stress (the main associated factor)
  • Hormonal changes in women (in premenstrual stages they are more frequent)
  • Immune system diseases
  • Nutritional deficiencies
  • Food allergies
  • Reaction to viruses or bacteria
  • Family history (there is genetic origin in recurrent cases of canker sores)
  • Oral injury due to dental care or orthodontic appliances
  • Poor oral hygiene

Are there foods that can cause mouth sores?

In a thesis from the University of Santiago de Compostela, researchers determined that micronutrients and macronutrients in the diet have no effect on the appearance of mouth sores. On the other hand, alcoholic beverages and caffeine do seem to increase the risk of this condition.

However, there are no studies that prove that a specific type of food causes these lesions. For now, some varieties have been identified that precipitate or worsen the symptoms. We reveal them below.

Acidic Fruits

As detailed in an article reported in the National Center for Biotechnology Information, consuming acidic fruits can further irritate the inflamed lining of the mouth. Because of this, they can cause more pain and discomfort in the case of sores. Some examples of these fruits are as follows:

  • Pineapple
  • Oranges
  • Lemons
  • Lime
  • Grapes
  • Strawberries

Tomato and its derivatives

Tomatoes and their derivatives are also characterized by a high level of acidity. For this reason, their consumption is not recommended until the lesions in the mouth have healed. Eating them can worsen irritation and pain in the mucous membranes of the mouth. It may even lead to the appearance of new sores.


Chocolate contains an alkaloid called obromide that tends to cause mouth sensitivity in some people. A publication via Valley Ridge Dental Centre explains that consumption of this food can trigger the appearance of sores on the tongue and inner cheeks of those who have a mild allergy to the food.

It should be clarified that it isn’t necessary to completely eliminate this food from the diet. Its intake is not recommended as long as the sores improve. It should also be avoided if there are signs of allergy.

Spicy foods

Spicy food does not cause mouth sores, but it can worsen their symptoms. Like acidic foods, they alter the inner lining of the mouth and cause irritation. Curries, hot sauces, jalapenos, and any other spicy foods should be avoided.

Hard or abrasive food

Hard or abrasive foods irritate the soft tissues of the mouth, thus worsening sores. In this group are nuts, carrots, coconut, and radishes, among others.


Although conclusive studies are lacking regarding the role of dairy in the appearance of mouth sores, it’s believed that some proteins in these foods derive an immune reaction that manifests with this symptom in some patients. In general, it’s suggested to discontinue their consumption if there are recurrent mouth sores.

In case studies reported in The Journal of the American Dental Association, the authors described the resolution of recurrent aphthous ulcers after the elimination of dairy products.

Other foods associated with mouth sores

  • Flour and its derivatives: People with a gluten allergy may experience this symptom.
  • Coffee and alcohol: Like several of the foods mentioned above, they can be very acidic, plus they are usually taken in large quantities.
  • Very spicy food: Due to their high salt content, these foods can be disruptive to the mucosa of the mouth.

Vitamins and mineral deficiencies that can cause mouth sores

To avoid mouth sores it’s not only necessary to limit certain foods. It’s recommended to consume various essential nutrients, such as folic acid, vitamin C, vitamin B, iron, zinc, and calcium.

A deficiency of these is also associated with the appearance of oral ulcers. To increase their levels, various foods can be eaten, such as those listed below.

  • Zinc: oysters, whole grains, and legumes
  • Iron: green vegetables, red meat, beans, and lentils
  • Folic acid: bread, rice, chickpeas, beans, fruits, and vegetables
  • Calcium: kale, broccoli, and certain types of fish, such as salmon
  • Vitamin B: red meat, yeast, and grains
  • Vitamin C: cabbage, parsley, watercress, papaya, and cauliflower

Like this article? You may also like to read: Mouth Piercing Could Have Oral Health Consequences

What to remember about food and mouth sores

In the end, there are several factors that cause mouth sores, but food itself is not. In rare cases, certain foods produce allergic reactions that manifest with this symptom. In addition, some precipitate or worsen the discomfort. Therefore, it’s important to know what they are and to limit their intake in the presence of these lesions.

It should be noted that the treatment of mouth sores is aimed at relieving the symptoms (with anesthetics or local steroids) and preventing recurrences. Often, they don’t require medical attention. However, if they don’t improve with time or cause a lot of pain, it’s best to consult a doctor.

All cited sources were thoroughly reviewed by our team to ensure their quality, reliability, currency, and validity. The bibliography of this article was considered reliable and of academic or scientific accuracy.

This text is provided for informational purposes only and does not replace consultation with a professional. If in doubt, consult your specialist.