Canker sores are a type of mouth sore. They’re not contagious, but they can be irritating and painful. Canker sore causes include stress, acidic foods and minor injuries to the inside of your mouth. Treatments include over-the-counter or prescription gels, ointments and rinses. Even without treatment, canker sores usually go away within two weeks.
Canker sores — or aphthous ulcers — are small, shallow ulcers that occur in the lining of your mouth. A canker sore starts as a white or yellowish mouth sore with a red border. They’re usually very small (less than 1 millimeter) but may grow to 1/2 inch to 1 inch in diameter.
You can get canker sores on your tongue, gums, roof of your mouth, inside of your lip or under your tongue. They can be painful and often make eating and talking uncomfortable.
There are two types of canker sores:
No. Canker sores aren’t herpes or any other type of sexually transmitted infection (STI). In fact, they’re not contagious at all. So, you can’t spread them through kissing or sexual contact.
No. Although these sores are often confused for each other, they’re not the same.
Cold sores — sometimes called fever blisters — are caused by herpes simplex virus type 1 (HSV-1) or type 2 (HSV-2). Because cold sores are caused by viruses, they’re highly contagious and can spread through close personal contact, such as kissing or oral sex. Cold sores are fluid-filled blisters, and they can appear in clusters on your mouth or genitals.
Canker sores, on the other hand, aren’t caused by an infection and aren’t contagious.
Anybody can develop canker sores. But they’re most common in teens and people in their 20s. Women and people assigned female at birth (AFAB) are more likely than men and people assigned male at birth (AMAB) to get canker sores. Experts believe this could be due to hormonal changes.
Canker sores are fairly common. Approximately 20% of the U.S. population has had a canker sore at least once in their lifetime.
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Common canker sore symptoms include:
In severe cases, you may also experience:
Experts aren’t exactly sure why some people are more likely to get canker sores. But they’ve discovered many factors that can trigger the development of these ulcers, including:
Complex canker sores may develop in people with immune system conditions, including:
Canker sores may also be linked to nutritional deficiencies in vitamin B-12, zinc, folic acid or iron.
No. Canker sores aren’t contagious because they’re not caused by an infection.
Canker sore treatment may include over-the-counter or prescription products to ease your symptoms. Your healthcare provider may recommend one or more of these canker sore remedies:
If you have canker sores caused by nutritional deficiencies, your healthcare provider may recommend certain vitamins or supplements.
For severe canker sores, your healthcare provider may recommend cauterization (burning the affected tissue). This can sterilize the area, reduce pain and speed up healing.
Canker sore pain usually improves in a few days and the ulcers typically heal within two weeks, even without treatment. If you have a canker sore that lasts for more than two weeks, schedule an appointment with your healthcare provider.
There’s no surefire way to prevent canker sores. But there are several things you can do to reduce your risk:
Try stress reduction techniques, such as mindfulness and meditation.
If you develop a canker sore, there are several over-the-counter treatments that can manage your symptoms, including rinses and topical ointments.
If you have canker sores that are unusually large, or if your symptoms interfere with your daily life, schedule a visit with your healthcare provider.
You should call your healthcare provider if you have canker sores that:
If you’ve scheduled an appointment with your healthcare provider, here are some questions you may want to ask:
A note from Cleveland Clinic
Canker sores can be irritating, and they’re certainly inconvenient, but they’re not dangerous. Unlike cold sores, canker sores aren’t caused by infections and can’t be spread from person to person. Most people find relief by using over-the-counter canker sore treatments. But if your symptoms don’t improve after trying these products, you should talk to your healthcare provider. They can tell you how to get rid of canker sores so you can get back to normal life.
Last reviewed by a Cleveland Clinic medical professional on 06/09/2022.
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