Canker sores often seem to pop up out of nowhere and, once you have them, they’re often painfully hard to ignore — especially when you try to eat or even talk.
So what, exactly, are canker sores? They’re an ulceration — basically, a small, open sore that’s inside your mouth. “They’re one of the most common oral diseases that are experienced by 20 percent of the population,” Dr. Alessandro Villa, an associate professor of oral medicine and head and neck surgery and chief of oral medicine at the University of California at San Francisco, tells Yahoo Life.
Canker sores — medically known as aphthous ulcers — primarily show up along the sides of the tongue, under the tongue, inside of the cheeks, or inside of the lips, according to Villa. “These are the most common areas,” he says.
They’re typically small, shallow, and white or yellowish with a red border around them. “That white part is essentially a scab inside your mouth,” Dr. Erinne Kennedy, a spokesperson for the American Dental Association and director of predoctoral dental education at Kansas City University, tells Yahoo Life. It’s the same concept as when “you skin your knee and go into the ocean and your scab turns white,” explains Kennedy. “The reason it looks like this is because it’s inside your mouth, so it’s wet all the time. It’s your body’s byproduct of trying to heal that ulcer.”
There are actually different types of canker sores, but the most common one is called minor aphthous stomatitis — a small sore that heals in about 10 days. There’s also a major version that’s a larger sore, which lasts two weeks or more and can be “very painful,” says Villa.
What, exactly, causes canker sores?
“Canker sores are tricky because they can be caused by multiple factors,” notes Kennedy. However, they’re often brought on by certain food sensitivities or allergies, so it’s worth paying attention to what you were eating leading up to developing a canker sore. “They might be sensitive to an acidic food such as pineapple, or a spicy food such as hot sauce,” explains Kennedy.
You can also develop a canker sore after a minor mouth injury or trauma, such as accidentally biting down on your cheek, tongue, or lip or eating sharp foods like potato chips. “Sometimes it can be triggered by stress,” says Villa, since stress can weaken the immune system.
Canker sores can also be a sign of a vitamin deficiency, such as being low in vitamin B12, zinc, folate, or iron, notes Villa.
In some cases, new products can bring on a canker sore. “If you started this new amazing toothpaste or mouth rinse and are starting to get canker sores, tell your dentist because they may be able to identify the ingredient and can help you find the product that’s contributing to canker sores,” says Kennedy.
Are canker sores the same thing as cold sores?
Some people get canker sores and cold sores confused, but they are two different conditions. Canker sores are not contagious and appear inside the mouth. Cold sores, on the other hand, are contagious — they’re caused by the herpes simplex virus — and tend to crop up outside the mouth, typically along the border of the lips. (The exception: The first outbreak of cold sores in children under 5 typically occurs inside the mouth, according to the American Academy of Dermatology.)
Many people with cold sores also experience a telltale burning, itching, or tingling sensation on or around the lips about a day before a small, hard painful spot appears, which is sometimes followed by one or more fluid-filled blisters that erupt, according to the Mayo Clinic.
How to get rid of canker sores
Canker sores typically heal on their own within 10 to 14 days, says Kennedy. “Right around the 10-day mark, they will resolve rather quickly,” she says.
So while you don’t need to treat them, there are things you can do both to help with the discomfort and possibly help canker sores heal a bit faster.
“You can use an over-the-counter topical anesthetic,” says Kennedy, which is applied directly to the canker sore. Products like Anbesol and Orajel contain benzocaine, which numb the area, providing some temporary pain relief. “It will make eating and drinking easier,” Kennedy says.
Also, try rinsing your mouth with warm salt water for about 30 seconds, which can help with the healing process. To create the rinse, place a teaspoon of salt in 1/2 cup of warm water and stir. “Salt water is a natural cleansing agent so it helps keep the area clean,” says Kennedy. Or you can use a hydrogen peroxide antiseptic rinse, such as Orajel Antiseptic Mouth Sore Rinse or Peroxyl, which promotes the healing of mouth sores.
For more severe canker sores, your dentist may prescribe topical corticosteroids to reduce inflammation, or an antibiotic if it gets infected. “But the majority of the time the sores will naturally heal on their own in about two weeks,” says Villa.
However, there are some red flags to look out for: “If you have a canker sore that doesn't heal after 14 days, you want to see your dentist to make sure it’s not something else,” says Kennedy. “If you develop other symptoms, like fever, diarrhea, rash, or headache see your doctor or dentist because that canker sore could be related to something systemic in your body.”
For example, mouth ulcers and diarrhea can be a sign of an inflammatory condition, such as Crohn’s disease, while small white lesions or patches that don’t go away can be a sign of oral cancer, so it’s best to get it checked out.
Another reason to head to the doctor: “If you have multiple canker sores and it’s interfering with your ability to eat or drink, see your dentist to get to the root cause,” suggests Kennedy.
How to prevent canker sores
The best way to prevent canker sores is to steer clear of what might be causing it, such as certain foods or stress, notes Kennedy. “If spicy or acidic foods or another specific food is causing canker sores in your mouth, it can be helpful to avoid those,” she says. “Certain stress management or calming techniques — meditation, exercise, journaling — can help reduce stress.”
In addition, Kennedy recommends being consistent with your oral hygiene routine — namely, flossing and brushing regularly, as well as “eating a well-rounded diet full of all the food groups to make sure you have the vitamins and minerals” your body needs.
Since being low in vitamin B12, zinc, folate, or iron can lead to canker sores, shoring up your diet with foods rich in those vitamins can help. Vitamin B12 is found in animal products such as fish, meat and dairy, as well as in fortified cereals. Zinc is found in red meat, poultry, beans and nuts, as well as fortified cereals. Folate is found in many foods, including dark leafy green vegetables (such as spinach, but also asparagus and Brussels sprouts), fruit, nuts, beans and enriched grains. And finally, good sources of iron include lean meats, seafood and beans, along with fortified cereals and bread.
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