Canker sores, or aphthous lesions, are a type of sore that can occur in the mouth, including on the tongue.

When canker sores do occur on the tongue, they can be very painful and make eating difficult. These lesions can closely resemble cold sores and other mouth sores, including those that occur with chickenpox.

In this article, we detail canker sore symptoms, causes, and treatments. We also explain when a person should seek medical attention for canker sores on their tongue.

Canker sores usually appear as small, round sores on the inside of the lip or cheek. When the sores appear on the tongue, they are often on the underside.

Canker sores may appear as one or several sores. In most cases, they are:

For some people, canker sores are a minor irritation. For others, the symptoms may include trouble sleeping, nausea, and stomach upset.

Canker sores may come back several times a year, usually occurring between three and six times.

Doctors do not know exactly what causes canker sores on the tongue. However, they have identified some potential risk factors that make a person more likely to get these sores:

  • recent injuries to the mouth, such as biting the tongue or harsh tongue brushing
  • history of radiation or chemical injury (such as a burn) to the mouth
  • lack of proper nutrients in the diet
  • stress and anxiety

As specific canker sore triggers vary among individuals, some doctors recommend that people keep a canker sore diary in which they note down when they have canker sores. Alongside this, people should record their diet, stress levels, and use of any new oral products, such as toothpaste or mouthwash, to see whether they can connect any of these factors to their canker sores.

For example, some people may find that they have an increased incidence of canker sores if they use toothpaste that contains sodium lauryl sulfate (SLS). Others may find that specific foods, such as cheese, cinnamon, citrus fruits, figs, or pineapples, may contribute to canker sores. Eliminating these potential triggers could help reduce the incidence of canker sores in some people.

Canker sores on the tongue are not contagious. Although it is not generally a good idea to share utensils or drinks, a person will not pass canker sores to others by doing so.

A person can treat canker sores on the tongue at home using a variety of topical and oral products. Examples of these treatments include:

  • Topical (gingival) hyaluronic acid: A person can apply topical hyaluronic acid directly to the sore using clean hands. The hyaluronic acid acts as a barrier between the sore and the rest of the mouth. People can purchase these over the counter (OTC) in 0.2% formulations, or a doctor or dentist can prescribe stronger treatments.
  • Supplements: Some people take supplements, including arginine, vitamin C, and lysine, to heal canker sores. There is no definitive dosage that may heal these sores, but researchers have used 3–5 grams (g) of arginine a day or 3–4 g of vitamin C taken over a day. People should always check with their doctor before taking any supplements to ensure that they do not interfere with other medications.
  • Antiseptic mouthwash: While OTC antiseptic mouthwash is not likely to reduce the incidence of canker sores, it may help reduce pain and discomfort on the tongue. Some people may also dilute hydrogen peroxide and use it as an oral rinse or purchase an oral rinse product containing this chemical. Learn more here.

In addition to these treatments, a person can take some at-home measures to reduce canker sore pain. These measures include avoiding foods known to irritate canker sores, such as those that are:

  • acidic, such as citrus fruits
  • crunchy
  • hard
  • salty

Medical treatments

A doctor can examine the ulcers and prescribe treatments, which may include:

  • mouthwashes, such as those that contain tetracycline antibiotics or chlorhexidine (an antiseptic)
  • topical corticosteroids to reduce inflammation
  • topical pain-relieving treatments

In rare cases, a doctor may prescribe immunosuppressants. These medications may suppress the body’s reactions to irritants, which may reduce the incidence of canker sores.

As there are no proven causes of canker sores, a person can reduce their risk using certain preventive measures. These include:

  • brushing the teeth and tongue gently with a soft- or medium-bristled toothbrush
  • eating a healthful diet that provides plenty of vitamins and minerals
  • taking steps to reduce stress, such as getting enough sleep, engaging in regular exercise, and taking at least 10 minutes to relax each day

For most people, canker sores on the tongue will go away within 7–10 days of first appearing. The ulcers usually do not scar. However, an estimated 10% of people experience sores that are larger than 10 mm across. These are large enough to cause scarring and may warrant a doctor’s treatment.

A person should also see their doctor if they experience the following symptoms in relation to canker sores:

  • eye discomfort
  • fever
  • rashes or sores that appear on other parts of the body
  • stomach pain
  • unexplained fatigue

These symptoms could indicate an underlying medical condition, such as Crohn’s disease or celiac disease, which may be contributing to the canker sores.

People should also see their doctor if they feel as though they almost always have canker sores or are worried that another medical condition may be causing these sores.

Canker sores on the tongue can be an irritating and sometimes painful occurrence that may temporarily limit speaking, eating, and swallowing.

Although most will go away without treatment, taking time to prevent and treat the ulcers may reduce this discomfort. If a canker sore persists, grows very large, or accompanies other symptoms, a person should see a doctor.