Most canker sores heal on their own within 10 to 14 days, but the right treatment can cut down on pain and help them resolve faster. These small, round ulcers form inside the mouth, typically on the inner cheeks, lips, or tongue, and while they’re not dangerous, they can make eating and talking miserable. Here’s what actually works to speed things along.
Make Sure It’s a Canker Sore
Before treating anything, confirm you’re dealing with the right problem. Canker sores and cold sores are frequently confused, but they’re completely different conditions. Canker sores are single, round white or yellow sores with a red border that form inside the mouth. Cold sores are clusters of small fluid-filled blisters that appear outside the mouth, usually around the lip border. Cold sores are caused by the herpes simplex virus and are contagious. Canker sores have no known viral cause and are not contagious at all.
If your sore is on the outside of your lips or looks like a cluster of tiny blisters, you likely have a cold sore and need antiviral treatment instead.
Simple Home Treatments That Help
A saltwater rinse is the easiest first step. Mix about half a teaspoon of salt into a cup of warm water and swish it around your mouth for 30 seconds, then spit. Doing this a few times a day helps keep the area clean and can reduce inflammation. It will sting briefly, but the discomfort fades quickly.
You can also dab a small amount of milk of magnesia directly onto the sore a few times daily. Some people find that holding a wet black tea bag against the ulcer for a few minutes provides relief, since tea contains compounds that may reduce irritation. A paste made from baking soda and a small amount of water, applied directly to the sore, can also neutralize acids in the mouth that aggravate the wound.
Over-the-Counter Pain Relief
Numbing gels containing benzocaine work by temporarily blocking sensation in the tissue around the sore. Products like Orajel Mouth Sore gel are widely available and provide quick, short-term relief, which is especially useful right before meals. Apply a small amount directly to the ulcer, and the area goes numb within a minute or two.
Antiseptic mouth rinses designed for oral sores can also help by reducing bacteria around the ulcer, which lowers the risk of secondary infection and may shorten healing time slightly. Look for rinses specifically labeled for mouth sores rather than standard mouthwash, which often contains alcohol that will burn intensely on contact.
Prescription Treatments for Stubborn Sores
If a canker sore hasn’t improved after two weeks or is unusually large and painful, a prescription-strength steroid paste can help. These work by reducing inflammation directly at the site. The paste is applied to the sore, where it forms a protective coating that also keeps food and saliva from irritating the wound. Your dentist or doctor can prescribe this if over-the-counter options aren’t cutting it.
Another option is chemical cautery with silver nitrate, which a dentist can apply in-office. This doesn’t speed up healing, but it can significantly reduce pain by essentially sealing the nerve endings in the ulcer. It’s a quick procedure, though the initial application can sting.
Foods That Make Things Worse
What you eat matters more than most people realize when a canker sore is active. Acidic foods like tomatoes, citrus fruits, and vinegar-based dressings directly irritate the exposed tissue. Spicy foods, salty snacks, and anything with sharp or rough edges (think chips, crusty bread, pretzels) can reopen the wound or delay healing.
Some foods are also linked to triggering canker sores in the first place. Common culprits include caffeine, eggs, cheese, peanuts, and almonds. If you get canker sores frequently, keeping a food diary can help you identify personal triggers. While you have an active sore, stick to soft, bland, cool foods. Yogurt, smoothies, mashed potatoes, and lukewarm soup are easier on the mouth.
Nutritional Deficiencies and Recurring Sores
People who get canker sores repeatedly sometimes have low levels of iron, folic acid, or vitamin B12. A clinical trial studying recurrent canker sores used 1,000 micrograms of sublingual vitamin B12 daily and found it worth investigating as a preventive measure. If your sores keep coming back every few weeks or months, it’s worth asking your doctor to check these levels with a simple blood test. Correcting a deficiency, if one exists, can dramatically reduce how often sores appear.
This is particularly relevant if you follow a vegetarian or vegan diet, have digestive conditions that affect nutrient absorption, or have noticed other symptoms of deficiency like fatigue or pale skin.
What Triggers Canker Sores
Beyond food, several other factors can set off a canker sore. Minor mouth injuries are one of the most common triggers: biting the inside of your cheek, brushing too aggressively with a hard-bristled toothbrush, or irritation from braces or dental work. Stress is another well-established trigger, and many people notice sores appearing during high-pressure periods at work or school.
Switching to a soft-bristled toothbrush and using toothpaste free of sodium lauryl sulfate (a foaming agent that irritates some people’s mouth tissue) can reduce how often sores develop. If braces or a dental appliance are causing repeated trauma to one spot, orthodontic wax applied to the offending bracket creates a buffer.
How Long Healing Takes
Minor canker sores, which account for the vast majority of cases, typically resolve within 10 to 14 days without any treatment at all. Pain usually peaks around days two through four and then gradually fades. With active treatment using numbing gels, rinses, and dietary changes, you can manage the discomfort effectively during that window even if the sore itself follows its natural timeline.
Major canker sores, those larger than about a centimeter across, can take six weeks or longer to heal and sometimes leave scarring. These are far less common but significantly more painful. If you have a sore that’s unusually large, lasts longer than three weeks, spreads, comes with a high fever, or makes it nearly impossible to drink fluids, that warrants professional evaluation rather than continued home treatment.