Canker sores are one of medicine’s minor mysteries. For the most part, doctors just shrug if you ask them the cause of these painful but usually short-lived lesions on the lining of the cheek or on the tongue.

They may suggest that the sores (called aphthous ulcers in medicalese) are the result of trauma from a toothbrush or sharp foods such as potato chips or crackers. But sometimes a canker sore pops up for no apparent reason.

Many people confuse canker sores with fever blisters or cold sores. But those lesions, which often appear on the lips or face, are caused by herpes simplex, while canker sores do not seem to be triggered by an infection.

Most canker sores clear up on their own in a week to 10 days, but some people suffer for much longer periods, and may even develop multiple sores.

In certain cases, the pain and irritation from a flare-up can make it hard to eat, talk, or swallow.


Sauerkraut Juice
Years ago, we heard from a retired doctor who was plagued with frequent canker sores. He was having trouble chewing his food, and the prescription drugs his physician had given him were not making much difference.

We suggested a humble home remedy that we had learned from a man whose mother worked as a dental hygienist during the Depression: swish a tablespoon of sauerkraut juice around in the mouth several times a day, swallowing the juice.

The desperate doctor reluctantly tried the remedy and reported that, to his amazement, it cleared the canker sores up right away.


Buttermilk
Another remedy that gets swished in the mouth and then swallowed is buttermilk. One reader offered this: “Swish your mouth twice a day with two tablespoons of buttermilk. If you don’t like the taste, spit it out. Enough friendly bacteria will stay to take care of canker sores. They will disappear in a few days.”

It may be the probiotic bacteria in buttermilk and sauerkraut juice that offer benefits. Unfortunately, it hasn’t been studied so we don’t really know.


Aloe Vera
One remedy that has been studied is a gel containing extracts of aloe vera and myrrh (Journal of Oral Pathology & Medicine, July 2014).

Some people might be tempted to use the gel from a fresh aloe vera leaf, but that can expose delicate tissues in the mouth to irritating aloe latex along with the gel.

Foods such as kiwi, green beans, and watermelon have also been used to speed healing of canker sores. Others find that avoiding certain foods is the best prevention.

People who are troubled with multiple canker sores may want to ask their doctors to test them for celiac disease, as recurrent aphthous ulcers may be a symptom of this condition.