What Causes Canker Sores and How to Treat Them

Canker sores are one of the most common conditions to affect the mouth. Approximately 1 in 5 people in the United States gets canker sores at least once in their lifetime. Most people develop canker sore symptoms for the first time as teenagers or young adults. Women are more likely to get canker sores than men. Please continue reading to learn what causes canker sores and how to treat canker sores.

What are canker sores or aphthous ulcers?

Canker sores (also called aphthous ulcers) are small, shallow mouth sores that develop in the mouth's mucous membrane (inner lining). They can form on your inner cheeks, lips, tongue, and gums.

Canker sores usually start as whitish or yellowish mouth ulcers with slightly red borders. They typically start out small at around 1 mm but can grow up to 1 inch in size.

A canker sore mouth ulcer can be of the following types:

Simple or minor canker sores: These are the more common type, accounting for 85% of cases. Minor canker sores can develop 3-4 times a year and usually heal in 1-2 weeks.
Complex or major canker sores: These are less common. People who have previously had major canker sores are more likely to develop them again.
Herpetiform canker sores. These are not common. They typically develop in older individuals. Despite the name, herpetiform canker sores are not caused by a herpes virus infection. They are pinpoint canker sores that occur in groups of 10 to 100 that can merge to form one large mouth ulcer, leaving behind a scar after healing.

Is a canker sore a sexually transmitted disease?

No, canker sores are not a sexually transmitted disease (STD) or sexually transmitted infection (STI). They are not contagious. A canker sore will not spread through kissing, skin-to-skin contact, or sexual contact.

Are canker sores and cold sores the same thing?

No, canker sores are not the same as cold sores (also called fever blisters). Cold sores are fluid-filled blisters that develop on the mouth and genitals. They are caused by the herpes simplex virus (HSV-1 or HSV-2). Unlike canker sores, cold sores are highly contagious. A cold sore can spread to others through kissing, oral sex, and close skin-to-skin contact. On the other hand, unlike cold sores, canker sores are not caused by an infection. You cannot get canker sores from another person.

What triggers canker sores?

Many things can trigger canker sores, including trauma or injury to the inner lining of the mouth, highly salty or acidic foods, and dental appliances like braces or poorly-fitting dentures. Nutritional deficiencies of vitamin B12, folic acid, zinc, and iron are also known canker sore causes. Certain medications such as ibuprofen and other nonsteroidal anti-inflammatory drugs (NSAIDs) may cause canker sores. Mental stress is also a known trigger.

People with weakened immune systems or immune system conditions like Behcet’s disease, lupus, celiac disease, Crohn’s disease, ulcerative colitis, and AIDS are at a higher risk of developing complex canker sores. Canker sores are believed to run in families. Women are more likely to develop canker sores due to hormonal changes.

What does a canker sore feel like?

Before a canker sore or aphthous ulcer becomes visible, it usually causes a burning or stinging sensation for a few hours. This is followed by the area turning red, swelling up, and becoming painful. The typical whitish-to-yellowish mouth ulcer forms within 1-3 days.

Canker sores may be painful and can make eating and talking difficult. When severe, symptoms of canker sores include fever, lethargy, and swollen glands in the neck (lymph nodes).

How are canker sores diagnosed?

Your doctor can diagnose canker sores with a physical examination. They may order blood tests to check for vitamin deficiencies.

How long do canker sores last?

Most canker sores, especially simple canker sores, heal and disappear entirely within two weeks, even without any treatment. Complex or major canker sores can take up to four weeks to heal and may leave a scar behind.

Most people develop canker sore symptoms 3-6 times a year. However, many people can go years before the next canker sore appears.

You should contact your doctor if you have severe canker sore pain or if your canker sores persist for more than two weeks. Rarely, major canker sores can become permanent or extremely painful, making it hard to eat, drink, and talk.

What gets rid of canker sores fast?

The best treatment for canker sores includes:

Topical anesthetics such as benzocaine and lidocaine for pain relief.
Mouth rinses containing chlorhexidine, hydrogen peroxide, or dexamethasone.
Topical corticosteroids like beclomethasone, fluocinonide, or hydrocortisone hemisuccinate ointments.
Antibiotics such as doxycycline for recurrent aphthous stomatitis (recurrent canker sores).
Vitamin supplementation to treat nutritional deficiencies.
Cauterization or burning of the ulcer to sterilize it, shorten healing time, and reduce pain.
Canker sore treatment with laser therapy to relieve ulcer pain and speed up healing.

How do I stop getting canker sores?

You cannot completely prevent canker sores. However, you can lower your risk of getting canker sores by:

Avoiding highly acidic, spicy, or salty foods, as well as alcohol and carbonated drinks.
Avoiding toothpaste containing sodium lauryl sulfate (SLS), which has been linked to canker sores.
Taking supplements to address any vitamin deficiencies, if present.
Practicing good oral hygiene by brushing your teeth twice daily and flossing daily.
Reducing stress with things like yoga, meditation, and mindfulness.