Most canker sores on the tongue heal on their own within two weeks, but you can speed up pain relief and support healing with a few simple treatments. These small, round ulcers (white or yellow with a red border) are not contagious and are not caused by a virus. They form inside the mouth, often on the tongue, inner cheeks, or lips.
Rinses That Help Healing
A salt water or baking soda rinse is the simplest first step. Dissolve one teaspoon of baking soda in half a cup of warm water and swish gently for 30 seconds or so. You can also use a basic salt water rinse at a similar ratio. Either option reduces acidity in your mouth and creates a less hospitable environment for irritation. Repeat several times a day, especially after meals.
Alcohol-free mouth rinses are another option. Avoid any rinse that contains alcohol, which will sting and can further irritate the sore.
Topical Pain Relief
Over-the-counter products containing benzocaine (sold under brand names like Orajel and Anbesol) numb the area on contact and make eating more bearable. Apply directly to the sore with a clean finger or cotton swab. You can also try dabbing a mixture of equal parts water and hydrogen peroxide onto the ulcer with a cotton swab, then following with a small amount of milk of magnesia. This combination can be repeated up to four times a day.
Pain from a canker sore typically starts improving within a few days, even if the sore itself takes one to two weeks to fully close.
What Triggers Canker Sores on the Tongue
Canker sores don’t have a single cause, but several well-documented triggers make them more likely. Biting your tongue, brushing too aggressively, or injuring the area during dental work are among the most common. Acidic and spicy foods, chocolate, coffee, strawberries, eggs, nuts, and cheese can all set off an episode in susceptible people.
Stress plays a role too, though it likely acts as a modifier rather than a direct cause. People under stress tend to clench, bite their cheeks or tongue, and engage in other habits that create the small injuries canker sores need to get started. Hormonal shifts during menstruation are another recognized trigger.
About 40% of people who get canker sores have a family history of them. If your parents dealt with frequent outbreaks, yours are likely to start earlier in life and be more severe.
Nutritional Gaps Worth Checking
Deficiencies in iron, vitamin B12, and folate show up roughly twice as often in people with recurrent canker sores compared to the general population. One study found that people with recurring ulcers consumed significantly less B12 and folate in their daily diets than matched controls. If you get canker sores frequently, it’s worth looking at whether your diet is low in leafy greens, legumes, eggs, meat, or fortified cereals, all good sources of these nutrients. A simple blood test can confirm whether a deficiency is contributing to your outbreaks.
Celiac disease is another connection. The intestinal damage from gluten sensitivity causes malabsorption of key nutrients, and recurring mouth ulcers are a recognized symptom of the condition.
Switch Your Toothpaste
Sodium lauryl sulfate (SLS) is a foaming agent found in most commercial toothpastes, and it has a clear link to canker sore frequency. A systematic review of clinical trials found that switching to an SLS-free toothpaste significantly reduced the number of ulcers, the duration of each ulcer, the number of episodes, and pain levels across all four measures. If you’re getting canker sores regularly, this is one of the easiest changes you can make. SLS-free options are widely available at most drugstores.
When a Canker Sore Needs Medical Attention
A typical canker sore resolves within two weeks without any treatment. See a healthcare provider if the sore lasts longer than three weeks, if new sores appear before old ones heal, if the ulcer is unusually large, or if your pain doesn’t respond to over-the-counter remedies. Painless mouth sores also warrant a closer look, since most canker sores hurt. Fever or diarrhea alongside mouth ulcers can signal an underlying condition like inflammatory bowel disease or celiac disease.
For severe or persistent cases, a provider may prescribe a steroid-based mouth rinse to reduce inflammation and accelerate healing. These rinses are swished and spit out several times a day for a set period, and they’re typically reserved for people whose sores are large, extremely painful, or keep coming back.
Canker Sores vs. Cold Sores
These two are frequently confused, but they’re entirely different. Canker sores appear inside the mouth, are not contagious, and have no known viral cause. Cold sores (fever blisters) appear outside the mouth, typically around the border of the lips, and are caused by the herpes simplex virus. Cold sores look like clusters of small fluid-filled blisters, while canker sores are single, round, open ulcers. If your sore is on your tongue or inner cheek, it’s almost certainly a canker sore.