Mouth Ulcer

Mouth ulcers are small sores that form on your gums, lips, tongue, inner cheeks or roof of your mouth. Lots of different things can cause them, including minor injuries, hormonal changes and emotional stress. Many mouth ulcers go away on their own. Others may require treatment.


Person pulling down lower lip to show mouth ulcer.
Mouth ulcers are often white or yellow in the middle with red around the edges.

What is a mouth ulcer?

A mouth ulcer is a sore that appears anywhere inside your mouth. These sores are usually red, yellow or white, and you might have one or several.

You can get mouth ulcers on your:

  • Gums.
  • Tongue.
  • Roof of mouth (palate).
  • Inner cheeks.
  • Inner lips.

These sores are often painful and can make eating, drinking and speaking uncomfortable.

Mouth ulcers can be alarming. However, they’re not a sexually transmitted infection (STI) and you can’t get or spread them from kissing or sharing food and drinks. Aside from any pain and discomfort, mouth ulcers are usually harmless and go away on their own in a week or two. But some types of mouth sores could point to underlying health conditions like viruses, autoimmune diseases or gastrointestinal issues.

Types of mouth ulcers

There are many different types of mouth sores and lesions, including:

  • Canker sores (aphthous ulcers). These are the most common type of mouth ulcers. Healthcare providers aren’t exactly sure what causes them or why some people get them more than others do. Causes include minor trauma (like biting your cheek), acidic foods and even stress. Canker sores are usually white or yellow with red around the edges.
  • Oral lichen planus. This condition can cause itchy rashes and lacelike, white sores inside your mouth. Oral lichen planus is an immune system response and most commonly affects women and people assigned female at birth (AFAB) age 50 or older.
  • Leukoplakia. This condition causes white or gray patches inside your mouth. It develops because of excess cell growth. Chronic irritation from things like smoking or chewing tobacco can cause it. But sometimes it happens for no apparent reason. Leukoplakia lesions usually aren’t cancerous.
  • Erythroplakia. Erythroplakia is another symptom of smoking or chewing tobacco. People with erythroplakia have red patches that commonly appear behind their lower front teeth or under their tongue. Unlike leukoplakia lesions, erythroplakia patches are usually precancerous or cancerous.
  • Oral thrush. An overgrowth of yeast called Candida albicans causes this fungal infection inside your mouth. It commonly happens after antibiotic treatment or when your immune system isn’t as strong as it usually is. Oral thrush causes red and creamy white mouth sores and patches.
  • Mouth cancer. Oral cancer lesions can show up as red or white mouth sores or ulcers. These sores won’t heal on their own. If you have a mouth ulcer that hasn’t gone away after three weeks, tell your healthcare provider.


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Symptoms and Causes

What are the symptoms of a mouth ulcer?

Mouth ulcers are usually easy to spot. They appear as sores on your gums, tongue, inner cheeks, inner lips or roof of your mouth.

Mouth sores are typically:

  • Red around the edges.
  • White, yellow or gray in the center.

You may only develop one ulcer, or there might be more. Other symptoms could include:

  • Swelling around the ulcers.
  • Increased soreness when brushing your teeth.
  • Pain that worsens when eating spicy, salty or sour foods.

What causes mouth ulcers?

Mouth ulcers may occur for a number of reasons, including:

  • Minor tissue injury from dental work, such as having a cavity filled.
  • Accidentally biting your cheek or tongue.
  • An allergic reaction to certain bacteria.
  • Wearing braces or retainers.
  • Using harsh or abrasive toothpaste.
  • Eating lots of acidic foods, such as oranges, pineapples and strawberries.
  • Hormonal changes during your period.
  • Stress.
  • Lack of sleep.

Health conditions associated with mouth ulcers

Certain health conditions, including many autoimmune diseases, can also cause mouth ulcers. These conditions may include:

Are mouth ulcers contagious?

No. Unlike cold sores, mouth ulcers aren’t contagious, and they can’t spread through kissing or sharing food.

Cold sores (fever blisters) appear on the outside of your mouth, often on your lips. A virus causes them, and they’re very contagious. If you have a fever blister, you should avoid sharing personal items with other people to reduce the spreading of the virus.


Diagnosis and Tests

How do health providers diagnose mouth ulcers?

A healthcare provider can diagnose a mouth ulcer with a visual examination. If you have a severe breakout, or if they suspect a specific health condition, they may order blood tests.

Management and Treatment

How do you treat a mouth ulcer?

While most mouth sores heal on their own, your provider may prescribe medications to help ease discomfort. Common mouth ulcer treatments include:

How to cure mouth ulcers fast naturally

There are also things you can do at home to relieve mouth sore symptoms:

  • Drink plenty of water.
  • Practice good oral hygiene to keep your mouth as clean as possible.
  • Rinse your mouth with warm saltwater a few times each day.
  • Make a mixture of equal parts hydrogen peroxide and water and rinse your mouth twice a day.
  • Avoid hot and spicy foods until the ulcer heals.
  • Use an over-the-counter (OTC) topical anesthetic like Orajel™ or Anbesol®.



Can I prevent mouth ulcers?

While you can’t prevent mouth ulcers altogether, there are things you can do to reduce your risk:

  • Brush your teeth twice daily and floss once daily for optimal oral health.
  • Use a soft-bristled toothbrush to avoid tissue irritation.
  • Eat a healthy diet rich in fresh fruits and vegetables.
  • Visit your dentist regularly for checkups and cleanings.

If your provider thinks you have an underlying condition that causes sores, treating your condition can reduce the risk of ulcers returning. Talk to your provider about ways to manage your health.

Outlook / Prognosis

How long do mouth ulcers last?

In most cases, mouth ulcers go away on their own in about 10 to 14 days. If you have a mouth sore that lasts longer than three weeks, schedule an appointment with your healthcare provider. They can recommend treatment and tell you how to get rid of your mouth ulcer.

Living With

When should I see my healthcare provider?

Anyone can get mouth ulcers. But you should call your healthcare provider if you have:

  • Mouth sores that last for three weeks or longer.
  • New sores that appear before the old ones heal.
  • Mouth ulcers that affect the outer part of your lips.
  • Pain that doesn’t improve with medication.
  • Unusually large mouth ulcers.
  • Mouth sores that are painless.
  • Fever.
  • Diarrhea.

What questions should I ask my healthcare provider?

If you get severe or frequent mouth ulcers, here are some questions you might want to ask your healthcare provider:

  • Why do I keep getting mouth ulcers?
  • Is an underlying condition causing them?
  • How can I reduce my risk?
  • What mouth ulcer medicine do you recommend?
  • Are there any changes I should make to my diet or lifestyle?

Additional Common Questions

Mouth ulcer vs. canker sore: What’s the difference?

“Mouth ulcer” is a broad term that describes any sore or ulceration inside your mouth. As we mentioned earlier, canker sores are the most common type of mouth ulcer. They affect about 20% of the general population. Many people use the terms “mouth ulcer” and “canker sore” interchangeably.

You might get a canker sore if you have a folate, vitamin B or iron deficiency. But in most cases, canker sores appear without a known cause and for no apparent reason. They can also recur (return), meaning they come and go over the course of your lifetime.

Some people confuse canker sores with cold sores (fever blisters), but they’re very different. A canker sore appears inside your mouth. A cold sore forms outside your mouth, usually on your lips. Canker sores aren’t contagious, but cold sores are.

How do you know if your mouth ulcer is bad?

Anytime you have a mouth sore that lasts longer than three weeks, schedule a visit with your provider. Mouth ulcers that don’t go away could point to other underlying health conditions.

Are mouth ulcers a sign of cancer?

Usually not, but it’s possible. A mouth ulcer that doesn’t go away could be a sign of oral cancer. In most cases of mouth cancer, mouth ulcers appear on or under the tongue.

Most mouth ulcers are harmless. But if you have a mouth sore that won’t heal, you should talk to a healthcare provider.

A note from Cleveland Clinic

Most mouth ulcers aren’t dangerous. But they can be a huge inconvenience. Mouth sores cause pain that can keep you from enjoying the things you love, like eating certain foods, drinking comfortably, playing an instrument or kissing your partner. Your mouth ulcer will probably go away within two weeks. In the meantime, you can try over-the-counter medications and home remedies to reduce pain until the sore heals. If you have a mouth ulcer that doesn’t heal after three weeks, schedule a visit with a healthcare provider. You might have an underlying condition that needs treatment.

Medically Reviewed

Last reviewed on 06/06/2023.

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