Mouth Sores: Types, What They Look Like, Causes, and Treatment

Mouth Sores: Types, What They Look Like, Causes, and Treatment
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Table of Contents

  1. Types of Mouth Sores
  2. Cold Sores/Oral Herpes
  3. Canker Sores
  4. Oral Thrush
  5. Leukoplakia
  6. Mouth Cancer
  7. Long Term Effects
  8. Prevention
  9. When to See a Doctor
  10. References

Sores and ulcers inside the mouth, a common malady, can have a variety of causes. Some are bacterial, some are viral and others can be fungal. They normally go away without treatment within two weeks, although any sores associated with cancer take much longer to heal and require much more treatment.

If you have mouth sores that last longer than two weeks, you should seek immediate medical attention. In these cases, sores should not be your primary concern. They could be are symptoms of an underlying disease or disorder.

Types of Mouth Sores

Just as mouth sores have a number of different causes, so too are there different types of sores. From cold sores to canker sores, from oral thrush to Leukoplakia to mouth cancer, each irritant comes with a particular set of symptoms, causes and treatments.

Cold Sores/Oral Herpes

Cold sores or fever blisters are painful clusters of fluid-filled blisters that may erupt on and along the edges of your lips.

Signs and Symptoms
  • A burning sensation on the spot where the blisters develop
  • Red painful blisters containing fluid may develop on or around your lips
  • Blisters may burst and ooze fluid
  • Some patients may experience fever
Cold sores are caused by the herpes simplex virus type 1. You may catch this highly contagious infection through contact such as kissing or oral sex.

Like most viral infections, cold sores have no cure. Blisters can still disappear in two to three weeks without intervention unless there are severe complications.

You may need to use prescription antiviral pills or creams if you keep experiencing blister outbreaks. This medication can also accelerate healing.

Canker Sores

Canker sores are white or gray oval-shaped ulcers that form inside your mouth. They range in size, from that of a pimple to the size of a dime. Regardless of size they’re painful, particularly when they contact acidic or salty liquids and foods.

The good news is, you can’t infect someone else.

Signs and Symptoms
  • One or multiple sores can develop inside of your mouth
  • The sores may be irritating (hot, spicy, or acidic foods can aggravate the pain)

Also called aphthous ulcers, canker sources don’t have a known cause. They are linked to issues such as:

  • Physical injury to the soft tissues inside your mouth
  • Defective immune system
  • Bacterial or viral infection

Canker sores don’t usually require treatment as they can naturally go away in about two weeks. You can treat them with:

  • Over-the-counter topical anesthetics to numb the affected areas
  • Saltwater rinses
  • Antimicrobial mouthwash
  • Antibiotic drugs to minimize secondary infection
  • Oral bandages (your dentist can provide these)

Oral Thrush

Oral thrush, or candidiasis, occurs as noticeable white patches on parts of the mouth like the tongue, inner cheeks, or roof. A yeast infection can also spread to your throat.

Signs and Symptoms
  • White patches covering a large section of your tongue
  • Soreness
  • Loss of taste
  • If your throat is also infected, you may experience pain when swallowing
  • Pain when eating
  • Cracked, reddish corners of the mouth

Thrush develops when there’s an excess growth of the usually harmless Candida fungus (yeast) in your mouth. The abnormal fungal buildup can occur when:

  • Your body’s natural defenses against infection are weak
  • You have low levels of helpful microbes in your body after using antibiotics
Your doctor may prescribe antifungal medication to restore a healthy balance of microbes in your mouth.


Leukoplakia is when slightly elevated white or gray patches form on your tongue, in your mouth, or on the insides of your cheeks. Unlike oral thrush, these patches can’t be scratched off.

Signs and Symptoms

Leukoplakia patches have the following characteristics:

  • Mostly white or grey in color
  • Slightly elevated
  • Hard, stubborn
  • The sores can irritate when you’re eating spicy or acidic food
  • Fuzzy in case of hairy leukoplakia

It’s not clear what causes leukoplakia. Doctors believe that the condition can develop when the mucous membranes lining the inside of your mouth are repeatedly disturbed.

Chronic irritations and other problems that may trigger leukoplakia include:

  • Jugged teeth
  • Damaged or rough dentures
  • Tobacco consumption (chewing, smoking, sniffing, etc.)
  • Excessive alcohol consumption
  • Epstein-Barr virus (causes hairy leukoplakia, which mostly affects HIV/AIDs patients and people with weak immune systems)

To treat leukoplakia, your doctor will recommend that you avoid potential triggers. These include tobacco products and alcohol.

Other remedies that can help clear the patches off your tongue include:

  • Dental care
  • Surgery or medicine can be used to remove the patch if first lines of treatment don’t work
  • If you have hairy leukoplakia, you can take antiviral drugs to treat it

Mouth Cancer

Mouth or oral cancer means cancerous growth on any part of your mouth. The harmful cells can affect parts such as:

  • Lips
  • Tongue
  • Inside of the checks
  • Mouth roof
  • Mouth floor
  • Gums
Signs and Symptoms
  • Painful sores that don’t go away in a few weeks
  • Unusual, persistent mouth lumps  
  • Loose teeth
  • Soreness in your mouth
  • White or red patches on the mucous membrane lining the inside of your mouth
  • Unusual speech difficulty

A variety of factors may trigger abnormal behavior of cells in your mouth or on your lips, causing oral cancer. These include:

  • Consumption of any type of tobacco product
  • Alcohol consumption
  • People with the human papilloma virus (HPV) infection at a higher risk of developing oral ulcers

Oral cancer can be treated using any or a combination of the following approaches:

  • Surgical removal of the cancerous cells (usually appropriate when the cancer hasn’t spread to multiple locations on your body)
  • Radiotherapy to eliminate the malignant growth
  • Chemotherapy (involves use of drugs to kill cancerous cells in your mouth)

Long Term Effects

Most mouth sores have short-term effects that go away in a few weeks.

However, recovery time and the risk of repeated outbreaks or long-term complications depend on factors like:

  • Your overall health
  • The type of oral ulcers you have
  • How strong your immune system is

Prolonged or severe issues that may arise from mouth sores include:

  • Recurring outbreaks if you have untreated HIV/AIDs or a weak immune system
  • Oral cancers and their treatments can cause dysphagia (swallowing problems), which may lead to pneumonia
  • Cancerous sores normally take longer to heal, even with treatment (advanced cases can return, including after surgical removal)

Prevention Tips

By adopting appropriate lifestyle habits, you can minimize your risk of developing mouth sores and related complications. These include:

  • Regular dental care, including having oral exams twice a year
  • Professional denture maintenance and hygiene  
  • Avoid tobacco products
  • Avoid or limit your alcohol consumption
  • Eat a healthy, balanced diet that includes vegetables and fruits to fortify your immune system
  • Don’t kiss people that have fluid-filled blisters on their lips
  • Minimize your exposure to sunlight
  • Don’t misuse antibiotics (if your throat hurts when swallowing while you’re on these drugs, let your doctor know right away)
  • Wash your hands frequently and avoid close contact with individuals that have contagious mouth sores

When to See a Doctor

Get medical attention as soon as possible if:

  • Your mouth sores are too painful to bear
  • Ulcers haven’t healed in two weeks
  • Mouth sores keep coming back


Cold Sore. (June 2020) Mayo Clinic.

Canker Sores. American Dental Association.

Candida Infections of the Mouth, Throat, and Esophagus. (February 2021). Centers for Disease Control and Prevention.

Leukoplakia. (November 2021). MedlinePlus.

Mouth Cancer (Overview). (July 2021). National Health Service.

Disclaimer: This article is intended to promote understanding of and knowledge about general oral health topics. It is not intended to serve as dental or other professional health advice and is not intended to be used for diagnosis or treatment of any condition or symptom. You should consult a dentist or other qualified healthcare provider with any questions you may have regarding a medical condition or treatment.