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Updated on October 3, 2022

Mouth Sores

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What are Mouth Sores?

Mouth sores are a common condition that many people experience at some point in their life. 

The ulcers affect your ability to eat, drink, and practice dental hygiene. They also make talking uncomfortable.

These sores may develop on any of your mouth's soft tissues, including your lips, cheeks, gums, tongue, floor, and roof.

You may also have mouth sores and inflammation on your esophagus, which is the tube that connects to your stomach.

Mouth sores, including canker sores, are typically harmless and last just a week or two.1 However, they may indicate oral cancer or a viral infection, such as herpes simplex.2

What Do Mouth Sores Look Like?

The majority of mouth sores are round or oval, with a white or yellow center and a red border. 

They form within your mouth, tongue, gums, or on your soft palate. 

A tingling or burning sensation may occur a day or two before the sores develop.

Types of Mouth Sores 

Here are the different types of mouth sores:

1. Canker Sores

Canker sores, also called aphthous ulcers, develop within the oral cavity.3 They appear as small ulcers with a white, yellow, or gray center and a flat red border. 

Severe canker sores may sometimes have a large diameter and a raised edge.

A canker sore typically starts as a red lump or patch. Before additional symptoms emerge, it may cause a tingling or burning sensation. 

Canker sores are painful. Fortunately, most canker sores heal on their own within 7 to 10 days.

There is limited research on the exact cause of canker sores. However, scientists have linked the condition to genetics. Other triggers include fatigue, stress, mouth tissue trauma, and certain foods (citrus and acidic).

2. Cold Sores

Cold sores are painful, fluid-filled blisters that form in clusters (often called fever blisters). They are often confused with canker sores, but have numerous differences between them. 

These unpleasant sores typically appear on the lips. However, they can also develop on the area surrounding the lips, the gum tissue around the teeth, or the bony roof of the mouth.

Herpes simplex virus (HSV) produces infectious cold sores. The first infection, which usually happens before adulthood, is frequently mistaken for a cold or the flu.

The infection produces painful sores all over the mouth. Some people can fall ill for up to a week. But the majority of people with herpes do not become ill.

Once a person is infected with herpes, the virus remains dormant in the body. Unfortunately, the virus reactivates in some people, causing cold sores to develop on the lips or other areas regularly.4

A ‘flare up’ may be triggered by several factors, including wind, sun, fever, or stress.

Cold sores often heal within a week. 

3. Candidiasis

Candidiasis is a yeast infection that is also known as oral thrush or moniliasis.5 It causes creamy white and red spots to appear on the mouth's surfaces. 

This condition may be painful. It can also cause foul breath and trouble eating and swallowing.

Candidiasis is most common in the very young, the elderly, and people with a weakened immune system (such as diabetes or AIDS patients). It is also common among individuals who wear dentures.

4. Leukoplakia

Leukoplakia is a condition in which a white or gray patch develops on the interior of the mouth. It is caused by abnormal cell growth in the mouth lining. It typically appears under the tongue or on the inside of your cheeks. 

Leukoplakia differs from other causes of white spots, such as thrush or lichen planus, in that it may progress to oral cancer.

Patches of leukoplakia appear gradually and heal over time.

Common causes of these mouth sores include:6 

  • Smoking or chewing tobacco
  • Certain foods
  • Cheek biting
  • Irregular dental restorations
  • Damaged teeth 

In some cases, it is impossible to pinpoint the cause of the sores.

Leukoplakia is usually of no concern, although it does have the potential of becoming cancerous.

5. Erythroplakia

Erythroplakia is a red, velvety lesion that may appear anywhere in the mouth. It is most often found on the gum tissue behind the back teeth or the floor of the mouth.7

The cause is unclear, although it is most likely linked to smoking tobacco and alcohol consumption.

Chronic inflammation and poor diet can also play a role. 

Although erythroplakia is less common than leukoplakia, biopsies reveal that most of these sores are precancerous or malignant.

6. Oral Cancer

White or red lesions, lumps, or ulcers in the mouth may all be signs of mouth cancer. It starts small and painless, but it rapidly grows and spreads. 

Most oral cancers are detected during routine medical checkups.

The sores from oral cancer may appear on the lips, tongue, gum or the roof of your mouth.

Contributing factors to oral cancer include smoking cigarettes, smokeless tobacco, and alcoholic beverages. According to experts, 90 percent of all oral cancer cases are due to the use of tobacco products.8

What Causes Mouth Sores?

You can develop mouth sores due to oral cancer, viral, fungal, or bacterial infections.

Other risk factors include:

  • Irritation to the mouth tissues (for example, if dentures don't fit perfectly and cause friction with the mouth tissues)
  • Injury or trauma from external objects such as orthodontic wires or sharp edges of broken tooth
  • Sensitivity to some ingredients found in toothpaste and mouthwashes
  • Medications or reactions to specific therapies such as cancer treatment
  • Systemic disorders such as oral lichen planus or inflammatory bowel disease
  • Recurrent canker sores
  • Tobacco use 
  • Exposure to irritants
  • Burns from hot foods or drinks
  • Acidic fruits
  • Spicy foods and drinks
  • Stress or lack of sleep
  • Tongue or cheek bites
  • Allergic response to certain foods or environmental elements
  • Nutritional deficiencies
  • Celiac disease

What Other Symptoms May Accompany Mouth Sores?

Mouth sores usually produce redness and pain, particularly while eating and drinking. They may also make the area surrounding the sore feel hot or tingly. 

It may be difficult to eat, drink, swallow, speak, or breathe, depending on the size, intensity, and location of the sores. Blisters may also form on the sores.

Other symptoms of mouth sores include:

  • Joint pains
  • Fever
  • Diarrhea
  • Painful blisters
  • A frequent outbreak of the sores
  • Swollen lymph nodes
  • Fatigue
  • Bleeding gums

What Health Issues Can Mouth Sores Indicate? 

Although mouth sores can be mild, harmless, and disappear within a few days, some mouth sores can be a sign of cancer, viral infection, bacterial infection, or fungal infection.

How to Get Rid of Sores in the Mouth

Most mouth ulcers will go away without treatment. However, if your mouth ulcers are frequent and painful, there are various things you can do to manage the condition. 

Either way, going to your doctor or dentist will be the best decision to rule out any underlying issues.

When to See a Doctor

If your mouth sores occur frequently, you may not know when it's the right time to see a doctor. 

Seek immediate medical attention if you notice any of the following:

  • Non-painful sores in one or more areas of the mouth
  • Unusually large sores
  • Rapidly spreading sores
  • Sores that are taking too long to heal (longer than three weeks)
  • A fever accompanying the mouth sores
  • The mouth sores developed after starting a new medication
  • Bacterial infections
  • Extreme difficulty eating or drinking

Professional Mouth Sore Treatments

When you see your doctor for mouth sores, they may prescribe a pain reliever, anti-inflammatory medicine, or steroid gel. 

If your mouth sores are caused by a viral, bacterial, or fungal infection, your doctor may prescribe antivirals, antibiotics, or antifungals respectively to treat the disease.

Some mouth sores may be treated with a low-powered laser, which provides instant pain relief and often prevents sores from recurring.

Chemically burning the sore with a tiny stick coated in silver nitrate may alleviate pain in a similar way, although it is not as effective as a laser.

If mouth cancer is suspected, your doctor will order a biopsy for further examination. If oral cancer is detected, he or she will prepare a treatment plan for you which may include surgery or chemotherapy.

Home Remedies for Mouth Sores

Here are some home treatments for mouth ulcers:

  • Gargle salt water and baking soda
  • Place milk of magnesia on the sores
  • Apply ice
  • Take over-the-counter medications if the sores are accompanied by pain
  • Use mouth rinses containing a steroid for pain management
  • Use topical pastes
  • Take nutritional supplements such as Vitamin B-6, B-12, folic acid, and zinc
  • Consider natural remedies such as myrrh, chamomile tea, and licorice root
  • Avoid acidic foods and drinks
  • Abstain from tobacco use
  • Avoid alcohol
  • Use a soft-bristled toothbrush
  • Use a toothpaste without sodium lauryl sulfate (SLS)
8 Sources Cited
Last updated on October 3, 2022
All NewMouth content is medically reviewed and fact-checked by a licensed dentist or orthodontist to ensure the information is factual, current, and relevant.

We have strict sourcing guidelines and only cite from current scientific research, such as scholarly articles, dentistry textbooks, government agencies, and medical journals. This also includes information provided by the American Dental Association (ADA), the American Association of Orthodontics (AAO), and the American Academy of Pediatrics (AAP).
  1. Canker sore,” Mayo Foundation for Medical Education and Research (MFMER)
  2. Herpes - oral,” National Institute of Health (NIH)
  3. Canker sore,” U.S National Library of Medicine (NLM)
  4. Human Herpesviruses: Biology, Therapy, and Immunoprophylaxis,” National Center for Biotechnology Information (NCBI)
  5. Fungal Diseases: Candidiasis,” Center for Disease Control and Prevention (CDC)
  6. leukoplakia,” Mayo Foundation for Medical Education and Research (MFMER)
  7. Erythroplasia (Erythroplakia),” Manson's Tropical Infectious Diseases, twenty-third Edition 2014
  8. Tobacco and Cancer” Center for Disease Control and Prevention (CDC)
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