Canker Sore
A canker sore, or aphthous ulcer is a mouth ulcer or sore that's open and painful. They're the most common type of mouth ulcer.

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Canker Sore

A canker sore, or aphthous ulcer, is a mouth ulcer or sore that’s open and painful. They’re the most common type of mouth ulcer. Some people notice them on the inside of their lip or cheek. They’re usually white or yellow and surrounded by red, inflamed soft tissue.

A canker sore can be simple or complex. A simple canker sore reemerges about three to four times every year. This is a common type in people between the ages of 10 and 20. A complex canker sore isn’t as common and develops in people who’ve had it before.

Neither type of canker sores is contagious, and both usually heal on their own within one to three weeks, although the pain normally subsides in seven to 10 days.

Contact your doctor or dentist if you develop:

  • large sores
  • an outbreak of sores
  • excruciating pain
  • a high fever
  • diarrhea
  • a rash
  • a headache

You should also seek medical care if you’re unable to drink or your canker sore hasn’t healed within three weeks.

What Are the Symptoms of a Canker Sore?

The symptoms of canker sores include:

  • a small, oval-shaped ulcer that’s white or yellow
  • a painful red area in your mouth
  • a tingling sensation in your mouth

In some cases, the following symptoms may also be present:

  • swollen lymph nodes
  • a fever
  • not feeling well

If a canker sore doesn’t heal on its own within two weeks, call your doctor. This could be a symptom of mouth cancer.

What Are the Causes and Risk Factors?

Your risk for developing canker sores increases if you have a family history of canker sores. There are various causes of canker sores. In some cases, the cause can’t be determined. The most common causes include:

  • a viral infection
  • stress
  • hormonal fluctuations
  • a food allergy
  • the menstrual cycle
  • a vitamin or mineral deficiency
  • an immune system problem
  • a mouth injury

How Is a Canker Sore Diagnosed?

Your doctor can often diagnose a canker sore just by looking at it. Your doctor may order blood tests or take a biopsy of the area if there’s a severe breakout or if they think you might have:

  • a virus
  • a vitamin or mineral deficiency
  • a hormonal disorder
  • a problem with your immune system
  • a severe breakout

A cancerous lesion may appear as a canker sore, but it will not heal without treatment.

How Is a Canker Sore Treated?

Canker sores normally heal without treatment. To speed up the healing process, you should avoid spicy foods. You should also brush and floss your teeth regularly to keep the area from becoming infected by bacteria.

Pain can be severe at times. You can lessen the discomfort several ways. For example, you can gargle with mouthwash or salt water. Although it will feel uncomfortable at first, it will help reduce pain. You can also use a topical agent such as Orabase to numb the area.

Your doctor or dentist can prescribe:

  • an antimicrobial mouth rinse
  • an antibiotic
  • a corticosteroid ointment
  • a prescription mouthwash

Tips to Prevent Canker Sores

You can prevent the recurrence of canker sores by avoiding foods that may have previously triggered the outbreak. These often include spicy, salty, or acidic foods. Also, avoid foods that cause the symptoms of an allergy, such as an itchy mouth, a swollen tongue, or hives.

If your canker sores pop up due to stress, you can use stress reduction methods and calming techniques, such as deep breathing and meditation.

Also, practice good oral health and use a soft toothbrush to avoid irritating your gums and soft tissue. Talk with your doctor to determine if you have any specific vitamin or mineral deficiencies. They can help design a suitable diet plan and prescribe individual supplements if you need them.

Written by: April Khan and Matthew Solan
Edited by:
Medically Reviewed by: [Ljava.lang.Object;@2e6e662e
Published: Jul 18, 2012
Published By: Healthline Networks, Inc.
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