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Everything You Need to Treat a Canker Sore, According to Dentists

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Canker sores (sometimes referred to as mouth ulcers or “aphthous ulcers”), can be intensely painful. The Mayo Clinic defines canker sores as “small, shallow lesions that develop on the soft tissues in your mouth or at the base of your gums.” And to clear up a common misconception, canker sores “are not the same thing as cold sores or herpetic sores,” says Dr. Tyrone Rodriguez, a pediatric dentist and ADA spokesperson. Canker sores only occur inside the mouth, and they are not contagious. While anyone can develop canker sores, Rodriguez tells us that certain people are particularly prone to them, and in general “about 20 percent of the population will experience them at least once per year.”

Both Rodriguez and Dr. Gerry Curatola, the founder of Rejuvenation Dentistry and author of The Mouth-Body Connection, underscored the difficulty of pinpointing the exact causes of canker sores, but common triggers include any sort of physical irritation inside the mouth (from braces, an accidental cheek bite, or aggressive brushing, for example), smoking (and vaping), and spicy food. Stress, lack of sleep, nutritional imbalance, or an autoimmune disorder can also cause flare-ups.

Additionally, when the “oral biome,” which Curatola describes as “the microbial ecosystem of your mouth,” gets out of balance, it changes the immune response and can lead to canker sores. “Look at it as an alarm bell and not an annoyance,” he says. If your canker sores are particularly painful and persistent, the experts said it’s best to speak with your dentist. But for standard-issue canker sores, there are some proven methods to deal with them — including topical treatments to provide relief and speed up healing, and toothpastes and mouthwashes that can minimize the occurrence of canker sores in the first place.

Best overall topical treatment for canker sores

The first line of defense when it comes to treating canker sores is often some sort of topical pain reliever. These can also help protect the sore from further irritation and speed up the healing process. One treatment Rodriguez and Curatola both recommend is applying milk of magnesia directly to canker sores. (They suggest using a Q-tip.) According to Curatola, the benefits are more “palliative,” and won’t necessarily help address the underlying cause, but it can still help with the pain. In order to get a stronger effect, Rodriguez suggests mixing one part milk of magnesia with one part Benadryl and then applying the same way, topically with a Q-tip. As Rodriguez explains, “Benadryl helps curb the inflammatory response that is somewhat responsible for causing the discomfort,” and milk of magnesia provides a soothing protective coating.

Best natural topical treatment for canker sores

Another pain-relieving topical treatment recommended by both dentists was clove essential oil, which they both warned is quite potent and should be applied in very small doses, again with a Q-tip or something similar. “It works for a lot of people,” says Rodriguez, adding that since clove oil is a “natural anaesthetic, it will help calm down those nerve endings so things don’t hurt as much. Curatola describes clove oil as working like “a natural Benzocaine.” (Benzocaine is the chemical anaesthetic in many popular topical gels.)

Best pain-relieving gel for canker sores

Orajel is likely the most widely available topical treatment made specifically for canker sores. It’s a pain-relieving gel that you can find in most drugstores. Rodriguez didn’t recommend a specific brand, but he said that benzocaine gels in general “will shut down the nerve endings, which helps with the discomfort, but it might not stop the [inflammatory] process.” An additional benefit of this type of gel, however, is that it forms a sort of protective coating over the sore which can help guard against further irritation.

Best overall mouthwash for canker-sore treatment

Mouthwash is another popular treatment method for canker sores, and many find it easier to use since you can simply swish it around your mouth and then spit it out. Both Rodriguez and Curatola mentioned baking soda rinses as an effective remedy because baking soda is “alkalizing.” As Rodriguez explains, “Mouth rinses with baking soda are effective because they raise the pH in the mouth so that things that are acidic and irritating won’t hurt as much, and this can also facilitate the healing process.” He recommends diluting one teaspoon of baking soda in a half-cup of warm water and then “swishing it around” in your mouth.

Best antiseptic mouthwash for canker-sore treatment

Hydrogen peroxide rinse is another popular remedy for cleaning and healing canker sores, and Rodriguez says it “can be effective,” but it’s very important to use a solution that’s 3 percent strength or less to avoid irritation. This Colgate peroxide rinse is diluted to 1.4 percent strength so it should be gentle enough, and it’s also alcohol-free, which is important because alcohol “can be an irritant” and further inflame sores.

Best mouthwash for canker-sore prevention

Both dentists told us that using alcohol-free mouthwash is also an important part of canker sore prevention. According to Curatola, alcohol dries out the “supportive film of the oral microbiome,” which he says is essential to maintaining a “balanced” and healthy mouth. “Saliva is the lifeblood of the mouth,” he says, adding that “when saliva flow decreases, you’re more prone to developing ulcers.” Using an alcohol-free mouthwash like this one will help prevent your mouth from drying out which can decrease the likelihood of developing canker sores. As Rodriguez puts it, “Saliva is naturally protective, so keeping things wet in your mouth is a good thing.”

Best SLS-free toothpastes for canker-sore prevention

Toothpaste can also trigger canker sores for some people. Rodriguez often tells patients who are having issues with mouth to sore to try out a new toothpaste brand and see if it helps. “I’ve had patients that have had success by switching brands, and some find that getting an SLS-free toothpaste helps.” SLS, or sodium laurel sulfate, is the chemical in toothpaste — and many soaps and shampoos — that creates a “foaming” effect. According to Rodriguez, SLS can act as act as an irritant for some and cause sores to develop. Rodriguez did not want to endorse a particular brand, but this toothpaste from Hello was our best-overall natural toothpaste, endorsed by two oral health experts, and it’s SLS-free.

Curatola also recommends going SLS-free, but he advises patients with canker-sore issues to avoid fluoride as well. “Fluoride can lead to cankers,” he says, because some types of fluoride “irritate the soft tissue in the mouth.” He also recommends looking at the ingredients list and avoiding anything with xylitol, an artificial sweetener in many toothpastes. “Xylitol can be very disturbing to the oral and gut microbiomes,” says Curatola.

Best toothbrushes for canker-sore prevention

Another potential cause of canker sores is aggressive brushing, which can irritate your gums and the inside of your mouth. Rodriguez likes some of the more advanced electric toothbrushes because they have pressure sensors “that let you know if you’re brushing too hard.” This Oral-B toothbrush was featured in our list of the best dentist-recommended electric toothbrushes, and it has a light-up pressure sensor to alert you when you’re applying too much force. Also, the small brush head would be helpful if you do have canker sores and need to navigate around them while brushing. (Most dentists agree that an electric brush is going to be more effective than a manual one, but if you prefer manual brushes Rodriguez recommends sticking with soft bristles.)

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How to Get Rid of Canker Sores, According to Dentists