Oral Care: Canker Sores



An aphthous ulcer, or canker sore, is a painful, open sore that forms in the mouth. About 1 out of 5 people experience a canker sore at some point during their life, with women slightly more likely than men to develop them. Although canker sores can occur at any age, they are more common in younger patients.

Signs and Symptoms

There are 3 general classifications for canker sores based on appearance and size. General symptoms include:

  • Painful red spot or bump that develops into an open sore
  • White or yellow in the middle of the ulcer
  • Diameter of <1 cm
  • A bright red area surrounding the ulcer

Causes/Common Triggers

The cause of canker sores is not fully understood and cannot always be determined. There are, however, some known triggers, including:

  • Nutritional deficiency (lack of vitamin B12, folic acid, or iron)
  • Emotional stress
  • Local trauma to the mouth
  • Autoimmune disorders
  • Hormonal changes (eg, menstrual period)

Tests and Diagnosis

Most canker sores are not caused by an underlying disease. A clinician can typically confirm a diagnosis by visually examining the sore. If sores are frequent and persistent, tests can be done to assess possible causes. A biopsy of the sore may be performed to differentiate between other causes of ulcers in the mouth.


Patients can take the following steps to prevent canker sores:

  • Avoid trauma to mouth, such as from rough food or hard-bristle toothbrushes
  • Manage stress
  • Repair damaged dental surfaces
  • Take vitamin and mineral supplements (as directed by a physician and/or pharmacist)
  • Consider switching to a different oral contraceptive


Patients can employ the following tips to manage a canker sore:

  • Avoid hot or spicy food
  • Avoid abrasive food that can irritate sores
  • Brush teeth gently and floss daily (to prevent the sore from being aggravated)
  • Use OTC medication or other remedies as directed by a physician and/or pharmacist

Treatment and Care

The best course of treatment should be determined by a physician and/or pharmacist. Most canker sores resolve without any treatment in about 7 to 10 days. If the sore persists, a clinician can prescribe topical anesthetics or pain relievers to help manage the symptoms.

Homeopathic and Alternative Remedies

Many individuals prefer to use homeopathic treatments. Although there are limited study data on their effectiveness, some health care providers recommend the following:

  • Natural herbal supplements
  • Vitamin/mineral supplements
  • Proper oral hygiene


A wide range of OTC medications are available to manage canker sores by treating pain or inflammation or soothing the ulcer, including ointments used for toothache, antiinflammatory gels, and mouthwash to help temporarily numb the lesions. Pharmacists should advise patients on the best OTC treatment option to meet their individual needs. Patients should inform their pharmacist of all prescriptions and other OTC medications being taken to avoid any drug interactions or contraindications.

Resources for Patients

The following resources may provide patients with more information on preventing and managing canker sores:

  • American Dental Association
  • Academy of General Dentistry
  • National Center for Biotechnology Information

Resources for Pharmacists

  • Colgate Professional
  • Crest/Oral B Dental Care
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