Mouth Sores

There are many types of mouth sores. Some, such as canker sores, are minor and can clear up on their own. Others, such as sores that develop from health conditions such as oral cancer, are more severe. Mouth sores can form on the cheeks, gums, tongue, floor and roof of the mouth; and lips.

This article discusses the possible causes of and treatments for various types of mouth sores.

A person with their eyes closed and their hand against the side of their face, like their jaw hurts.

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Symptoms of Mouth Sores

The symptoms that develop along with mouth sores depend on the type and cause. Some of the symptoms that can come with mouth sores include:

  • Burning or tingling sensations in the mouth (specifically near the sore)
  • Having difficulty eating foods that are spicy or salty
  • Stinging
  • Bleeding
  • Difficulty swallowing
  • Breaks in the skin that do not heal (ulcerations)
  • Sores that do not heal
  • Unintentional weight loss
  • Loose teeth
  • Red or white patches in the mouth or on the tongue

Mouth sores can present with some or all of the above symptoms.

Mouth Sore Duration and Severity

Typically, the longer a sore lasts, the more likely it is to be associated with a more severe health condition. Mild irritations that cause sores tend to heal faster.

Causes of Mouth Sores

There are several health conditions that can cause mouth sores to develop, including:

  • Idiopathic: Idiopathic mouth sores occur but are not linked to an underlying health condition. Canker sores are an example of this type of mouth sore.
  • Autoimmune diseases: Some autoimmune diseases—such as Crohn’s disease, lichen planus, and systemic lupus erythematosus—can cause sores to develop in the mouth.
  • Trauma: Trauma such as biting your cheek or burning your mouth can cause a mouth sore. In some cases, trauma from dental tools can also cause a mouth sore.
  • Hematologic: Hematologic disorders are disorders of the blood. Anemia and neutropenia are blood disorders that can cause mouth sores.
  • Fever syndromes: Certain disorders that cause a fever without an infection (fever syndromes) can cause mouth sores.
  • Cancer: Certain types of cancers can cause painful mouth sores.
  • Food allergies: Some food allergies are a common cause of mouth sores.
  • Vesiculobullous disorders: These conditions only affect the mouth and are characterized by the mouth sores they cause.
  • Nutrient deficiencies: Being deficient in nutrients like iron, folate, zinc, or several B vitamins can lead to mouth sores.
  • Viral infections: Viral infections such as herpes simplex, shingles, Coxsackie A, Epstein-Barr, and human immunodeficiency virus (HIV) can cause sores to develop in the mouth. COVID-19 has also been shown to cause oral lesions in some people.
  • Bacterial infections: Syphilis and tuberculosis are bacterial infections that can cause mouth sores.
  • Inherited disorders: Epidermolysis bullosa and chronic granulomatous disease can cause sores to develop in the mouth.
  • Oral infections: Some oral infections, such as gingivostomatitis, cause mouth sores. Gingivostomatitis is caused by a primary infection, such as herpes simplex.

How to Tell What Type of Oral Sore You Have

It’s can be hard to tell the difference between a severe mouth sore that needs medical treatment and a minor one you can let heal on its own. Take note of any other symptoms you have and see if the sore clears up on its own within a week. If it doesn't, call your healthcare provider.

What Medications Can Cause Mouth Sores?

There are several types of drugs that can cause oral sores or ulcerations, including:

Medication and Mouth Sores

If you develop mouth sores, do not stop taking your medication without talking to your healthcare provider first. The mouth sores might be a temporary effect of the drug and will go away soon. If not, your provider may adjust your dose or switch you to a different medication.

How to Treat Mouth Sores

Treating mouth sores means treating the cause. Idiopathic mouth sores will typically clear up on their own within one to three weeks.

If you are having a lot of pain or get recurrent idiopathic mouth sores, you can try numbing gels, antiseptic mouthwashes, or anti-inflammatory medications to ease pain and promote healing.   

Mouth sore treatment according to the underlying cause includes:

  • Autoimmune diseases: Treatment for autoimmune disorders depends on many factors, such as the type of disease and the person receiving treatment. Some options include corticosteroids, biologics, immunosuppressant medications, and disease-modifying anti-inflammatory drugs.
  • Trauma: Depending on the extent of the trauma, you may have to wait for the sore to heal on its own. You can help the healing process by rinsing your mouth out with saltwater daily, eating soft foods, and using a topical pain reliever made specifically for your mouth.
  • Hematologic: Different treatments are required for different blood disorders. Blood transfusions, medications designed to thicken or thin the blood, and aspirin are all possible options for treating blood disorders.
  • Fever syndromes: There is no one treatment option for fever syndromes. Some immune system-stimulating drugs, such as interleukin 1, have been used to treat these disorders.
  • Vesiculobullous disorders: Some vesiculobullous diseases will go away and return on their own. There are some treatments, such as corticosteroids, antibiotics, and immunosuppressants.
  • Nutrient deficiencies: Eating more nutrient-rich foods or using supplements that bridge any gaps in nutrition can help address deficiencies.
  • Viral infections: Viral infections do not always require treatment. If they do, antivirals will be used.
  • Bacterial infections: Bacterial infections are treated with antibiotics. The length and type of antibiotics used will depend on the severity of the illness and the bacteria causing the infection.
  • Inherited disorders: There is no cure for inherited diseases, but they can be treated using a variety of different therapies, including antidepressants, epilepsy medications, and acetaminophen (Tylenol) for pain.
  • Oral infections: Oral infections have a variety of treatments, including numbing gel and over-the-counter (OTC) pain relievers, antibiotics, and mouth rinses.

Treating the Cause

If an underlying health condition is causing mouth sores, treating that condition will usually clear up the mouth sores. In the meantime, ask your healthcare provider about treatment to ease your symptoms.

Are There Tests to Diagnose Mouth Sores?

There are several different tests used for diagnosing mouth sores because there are many possible causes.

To determine what is causing the mouth sores, your healthcare provider will look at the inside of your mouth and assess the sore(s). They will also you about any other symptoms you are experiencing and about any medications you are on. Other factors that are considered in the diagnostic process include:

  • How long you’ve had the sores
  • If the sores heal and then come back again
  • Where the sores are in the mouth

Your provider may do other tests if they think an underlying health condition is causing the sores based on your other symptoms. Usually, this will include doing blood tests.

Why Is Getting the Right Diagnosis Important?

Some mouth sores are harmless, but others can indicate a severe health condition. You want to be sure that your mouth sores do not require treatment before you leave them alone to heal on their own.

When to See a Healthcare Provider

You cannot self-diagnose a mouth sore. Your healthcare provider needs to look at the sores to figure out what they are being caused by. This is especially important if you have mouth sores that do not heal in a few weeks or continue to come back after they do heal.

You should also see your provider if you are experiencing any symptoms along with the sores, such as pain and difficulty eating or swallowing. You should also see a provider if you think you have an infection or have symptoms of an infection.

Recent chemotherapy, radiation, or starting a new medication, are other factors that would prompt a call to your provider.


Mouth sores can develop anywhere in the mouth, including the tongue, inside the cheeks, the roof of the mouth, underneath the tongue, and the lips. While many types of mouth sores are harmless and only cause mild pain or irritation, others can be signs of more severe health conditions.

Typically, mouth sores that develop because of a disorder will also come with other symptoms such as fever, difficulty swallowing, or unintentional weight loss.

It's important to see your provider to find out for sure what is causing your mouth sores. That way, you can address any underlying condition that's causing them instead of leaving them to heal on their own when they require treatment.

A Word from Verywell

There are many causes of mouth sores. While not all of them are serious, it's important to find out why they are happening—especially if they don't heal on their own or keep coming back. Your provider can do tests to find out what's causing your mouth sores and recommend the best treatment.

Frequently Asked Questions

  • What causes mouth sores?

    Mouth sores can be idiopathic, which means there is no known underlying cause. They can develop "out of the blue" or after mild trauma such as biting the inside of your cheek. In some cases, mouth sores can develop because of an underlying health condition such as a viral or bacterial infection, blood disorder, or autoimmune disease.

  • Are canker sores serious?

    Canker sores are rarely severe and are usually considered to be idiopathic. That said, they can also be triggered by eating acidic foods, stress, and injury to your mouth. If you get recurrent canker sores, contact your healthcare provider.

  • Will I be able to tell if my mouth sore is cancerous?

    It can be hard to tell the difference between a benign mouth sore and one that is cancerous. Things to look out for if you are worried about cancer are white or reddish patches on the inside of the mouth, loose teeth, or a sore that does not heal. If it's caught early enough, mouth cancer is highly treatable.

16 Sources
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By Angelica Bottaro
Angelica Bottaro is a professional freelance writer with over 5 years of experience. She has been educated in both psychology and journalism, and her dual education has given her the research and writing skills needed to deliver sound and engaging content in the health space.