Mouth Ulcer


What is a mouth ulcer?

A mouth ulcer is a sore that develops in the soft tissue lining of your gums, tongue, inner cheeks, lips or palate. They’re usually yellow or red, and they can be quite painful. Mouth ulcers may also be called aphthous ulcers or canker sores.

What is the difference between mouth ulcers and cold sores?

Mouth ulcers form inside your mouth. They’re due to irritation, injury, vitamin deficiencies or other factors. Cold sores, on the other hand, appear on your lips and are caused by a virus. Mouth ulcers aren’t contagious, but cold sores are.

Who do mouth ulcers affect?

Mouth ulcers can affect people of all ages. Most of the time, having a mouth ulcer is more of an inconvenience than a serious medical concern. While mouth ulcers themselves are not considered dangerous, they have been linked to serious health conditions, including:

How common are mouth ulcers?

Mouth ulcers are one of the most common lesions affecting the mouth. Approximately 20% of people will develop a mouth ulcer at some point.

Symptoms and Causes

What are the symptoms of a mouth ulcer?

Mouth ulcers are easy to spot. They usually appear as sores on your lips, gums, tongue, inner cheeks or roof of the mouth. While red around the edges, mouth ulcers are typically 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 ulcer.
  • Increased soreness when brushing your teeth.
  • Pain that worsens when eating spicy, salty or sour foods.

What causes mouth ulcers?

The exact cause of mouth ulcers is unknown. But there are several factors that can contribute to the development of these sores:

  • Minor tissue injury from dental work, such as having a cavity filled.
  • Accidentally biting your cheek or tongue.
  • Allergic reaction to certain bacteria.
  • Wearing orthodontic braces or retainers.
  • Vitamin deficiencies.
  • Using harsh or abrasive toothpaste.
  • Eating a lot of acidic foods, such as oranges, pineapples and strawberries.
  • Hormonal changes during your period.
  • Stress.
  • Lack of sleep.
  • Viral, bacterial or fungal infections.

Are mouth ulcers contagious?

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

Diagnosis and Tests

How are mouth ulcers diagnosed?

Your healthcare provider can diagnose a mouth ulcer with a visual examination. If you have a severe breakout — or if they suspect the condition is caused by a virus or mineral deficiency — they may order blood tests.

Management and Treatment

How are mouth ulcers treated?

While most mouth ulcers heal on their own, topical treatments may be prescribed to ease discomfort and reduce the risk of complications. Common mouth ulcer treatments include antiseptic gels, steroid ointments or medicated mouth rinses. In severe cases, your healthcare provider may prescribe immunosuppressants.

Are there home remedies for mouth ulcers?

There are also several things you can do at home to relieve discomfort associated with oral lesions. Here are some tips for healing a mouth ulcer:

  • Use over-the-counter topical anesthetic, such as Orajel™ or Anbesol®.
  • 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.
  • Avoid hot and spicy foods until the ulcer heals.

How long do mouth ulcers take to heal?

In most cases, mouth ulcers resolve themselves in about 10 to 14 days. If you have a mouth ulcer that lasts longer than three weeks, schedule an appointment with your healthcare provider.


How can I prevent mouth ulcers?

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

  • 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 healthcare provider determines that your mouth ulcers are connected to an underlying health issue, managing your condition can reduce the risk of ulcers returning.

Outlook / Prognosis

What can I expect if I have this condition?

If you get a mouth ulcer, it will likely clear up in two weeks or less. If you develop frequent ulcers, talk with your healthcare provider. They may be able to determine what is causing the issue. No matter the root cause, mouth ulcers can be successfully managed with the right treatment.

Living With

When should I see my healthcare provider?

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

  • Ulcers that last for three weeks or longer.
  • New ulcers 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.
  • A fever.
  • Diarrhea.

Frequently Asked Questions

Are mouth ulcers a sign of COVID-19?

Yes, it’s possible. Recent studies have found that mouth ulcers may appear during the infectious period of COVID-19.

Are mouth ulcers a sign of cancer?

Yes, sometimes. A mouth ulcer that doesn’t go away could be a sign of oral cancer. In most cases, ulcers caused by oral cancer appear on or under the tongue.

What can you tell me about mouth ulcers in kids?

Kids can develop mouth ulcers just like adults. You can manage symptoms by giving your child over-the-counter pain relievers, such as acetaminophen or ibuprofen. Ice, popsicles or cold liquids may help soothe the area. If your child has a mouth ulcer that hasn’t healed in two weeks, call your healthcare provider.

A note from Cleveland Clinic

While mouth ulcers usually aren’t dangerous, they can certainly be painful and inconvenient. Fortunately there are several mouth ulcer treatments and remedies that can ease your symptoms until your lesions heal.

Last reviewed by a Cleveland Clinic medical professional on 09/07/2021.


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