Canker sores are small, painful ulcers on the inside of the mouth, lips, or throat.

• Symptoms of canker sores include small, painful, crater-like ulcers.
• See a doctor if canker sores are accompanied by fever, last more than three weeks, or the affected individual has difficulty swallowing.
• Multiple factors may cause canker sores, including injury to the mouth, acidic or spicy foods, vitamin deficiencies, hormones, stress, or autoimmune disorders.
• Canker sores are not the same thing as fever blisters (cold sores).
• Most canker sores require no treatment and resolve on their own.
• To help relieve pain and speed healing, treatments and remedies for canker sores include topical medications, mouthwashes, and over-the-counter pain medications.
• People with frequent canker sores should see their doctor to get tested for possible underlying medical conditions.

What are canker sores?

Canker sores (aphthous ulcers or aphthous stomatitis) are small, painful ulcers inside the mouth. They may occur on the tongue and on the inside linings of the cheeks, lips, and throat. They usually appear white, gray, or yellow in color, with a red border.

Canker sores are the most common type of oral lesion, affecting about 20% of people. Women get canker sores more often than men. Canker sore susceptibility may be inherited, and the condition can run in families.

Canker sores are not the same as cold sores (fever blisters), which are an infection caused by the herpes virus and are contagious. Canker sores are not contagious and are categorized into three types:

1. Minor sores measure from 3 to 10 millimeters (mm) and are the most common type of canker sore. Lesions last 10 to 14 days and heal without scarring.
2. Major sores are larger and deeper than minor sores, have an irregular border and a diameter of greater than 10 mm. Major canker sores may take weeks to months to heal and can leave a scar after healing.
3. Herpetiform sores are characterized by large groups of multiple sores. These are small ulcers (2-3 mm) but there may be as many as 100 ulcers present at the same time. They tend to heal without scarring.

There are several types of canker sores, including minor, major and herpetiform sores.

Minor canker sores

Minor canker Sores are the most common and:

• Are usually small
• Are oval shaped with a red edge
• Heal without scarring in one to two weeks

Major canker sores

Major canker Sores are less common and:

• Are larger and deeper than minor canker sores
• Are usually round with defined borders, but may have irregular edges when very large
• Can be extremely painful
• May take up to six weeks to heal and can leave extensive scarring

Herpetiform canker sores

Herpetiform canker Sores are uncommon and usually develop later in life, but they're not caused by herpes virus infection. These canker sores:

• Are pinpoint size
• Often occur in clusters of 10 to 100 sores, but may merge into one large ulcer
• Have irregular edges
• Heal without scarring in one to two weeks

The precise cause of canker sores remains unclear, though researchers suspect that a combination of factors contributes to outbreaks, even in the same person.

Possible triggers for canker sores include:

• A minor injury to your mouth from dental work, overzealous brushing, sports mishaps or an accidental cheek bite
• Toothpastes and mouth rinses containing sodium lauryl sulfate
• Food sensitivities, particularly to chocolate, coffee, strawberries, eggs, nuts, cheese, and spicy or acidic foods
• A diet lacking in vitamin B-12, zinc, folate (folic acid) or iron
• An allergic response to certain bacteria in your mouth
• Helicobacter pylori, the same bacteria that cause peptic ulcers
• Hormonal shifts during menstruation
• Emotional stress

Canker sores may also occur because of certain conditions and diseases, such as:

• Celiac disease, a serious intestinal disorder caused by a sensitivity to gluten, a protein found in most grains
• Inflammatory bowel diseases, such as Crohn's disease and ulcerative colitis
• Behcet's disease, a rare disorder that causes inflammation throughout the body, including the mouth
• A faulty immune system that attacks healthy cells in your mouth instead of pathogens, such as viruses and bacteria
• HIV/AIDS, which suppresses the immune system

Unlike cold sores, canker sores are not associated with herpes virus infections.

In most cases, canker sores do not require any treatment. If a person already has a canker sore, there are steps that can be taken to help relieve the pain or irritation caused by the sore and speed healing:

• Topical medications applied directly on the sore, mouthwashes, and oral medications can relieve pain or inflammation.
• Avoid acidic foods such as citrus fruits or spicy foods that may aggravate the sore.
• If there is any vitamin deficiency (a doctor can test for this), take supplementation as prescribed.
• Brush teeth gently and use a brush with soft bristles.
• Use toothpaste and mouthwash that does not contain sodium lauryl sulfate.
• Another home remedy is to mix milk of magnesia with Benadryl liquid and use as a mouth rinse.
• Other natural remedies include goldenseal mouth rinse, deglycyrrhizinated licorice (DGL) gargled in warm water, and saltwater rinses.

Anyone can develop canker sores. But they occur more often in teens and young adults, and they're more common in females.

Often people with recurrent canker sores have a family history of the disorder. This may be due to heredity or to a shared factor in the environment, such as certain foods or allergens.