Most mouth ulcers (canker sores) heal on their own within 10 to 14 days, but you can speed that up and reduce pain significantly with a few targeted strategies. These small, round sores with a white or yellow center and red border form inside the mouth, typically on the inner cheeks, lips, or tongue. They’re not contagious and aren’t caused by a virus. Here’s what actually works to get rid of them faster.
Salt Water Rinses: The Simplest Starting Point
Dissolving half a teaspoon of salt in a cup of warm water and swishing for 30 seconds is one of the most effective things you can do at home. A study published in PLOS One found that rinsing with salt solution (0.9 to 1.8% concentration) stimulates the cells responsible for wound repair to migrate toward the injury site faster. The salt also triggers increased production of collagen and structural proteins that rebuild tissue. The chloride ion specifically drives this healing response.
Rinse three to four times a day, especially after meals. It stings for a moment, but the effect is genuinely therapeutic, not just soothing. You can also try a baking soda rinse (one teaspoon in half a cup of water), which neutralizes acids in the mouth that irritate the ulcer.
Honey as a Healing Agent
Applying a small amount of raw honey directly to the ulcer is surprisingly effective. In a comparative study, honey-treated ulcers healed in an average of 2.7 days, compared to 5.9 days for ulcers treated with a standard prescription corticosteroid paste. Honey has natural antibacterial properties and creates a protective barrier over the sore. Dab it on gently a few times a day, ideally after rinsing your mouth.
Over-the-Counter Pain Relief
If the ulcer is making it hard to eat or talk, numbing gels containing lidocaine (typically 2%) or benzocaine can help. These are applied directly to the sore and begin reducing pain within about 10 minutes. The relief lasts roughly 30 minutes to an hour, so you may need to reapply before meals. Look for oral-specific gels at any pharmacy. Avoid using more than four applications per day.
Protective pastes that contain ingredients like carboxymethylcellulose form a physical barrier over the ulcer, shielding it from food and friction. These can be especially useful if the sore is in a spot that gets constantly rubbed by your teeth or braces.
What to Avoid While It Heals
Acidic foods like tomatoes, citrus fruits, and vinegar-based dressings will aggravate the ulcer and slow healing. Spicy foods, crunchy chips, and very hot beverages do the same. Stick to softer, cooler, and blander foods until the sore closes.
Your toothpaste may also be part of the problem. Many common brands contain sodium lauryl sulfate (SLS), a foaming agent that irritates oral tissue. In one study, people who switched to an SLS-free toothpaste saw their ulcer count drop from about 14 sores over three months to just 5. If you get mouth ulcers frequently, switching toothpaste is one of the easiest changes you can make.
When Ulcers Keep Coming Back
Recurring mouth ulcers often signal a nutritional gap. Research consistently links them to deficiencies in iron, folic acid, and vitamin B12. In a study of 80 patients with recurring ulcers, about one in four had a deficiency in at least one of these nutrients. Iron deficiency was confirmed by significantly lower ferritin levels in ulcer patients compared to healthy controls.
Vitamin B12 supplementation has the strongest evidence for prevention. A review of clinical trials found that taking 1,000 micrograms of B12 sublingually (dissolved under the tongue) daily for six months significantly reduced the number, duration, and frequency of ulcer outbreaks. In one trial, 77% of participants reported meaningful improvement using B12 buccal discs. If you’re dealing with ulcers every month or two, it’s worth having your B12, iron, and folate levels checked.
Stress, hormonal changes, and minor mouth injuries (like biting your cheek or irritation from braces) are other common triggers. Unlike cold sores, canker sores have no single identifiable cause, which is part of why they’re so frustrating.
Canker Sores vs. Cold Sores
The easiest way to tell these apart is location. Canker sores only appear inside the mouth. Cold sores form on the outside, usually around the border of the lips. Cold sores are clusters of small fluid-filled blisters caused by herpes simplex virus type 1. Canker sores are single, round, white or yellow sores with a red border, and they’re not viral or contagious. The treatments are completely different, so knowing which one you have matters.
Types of Mouth Ulcers and Healing Times
Not all canker sores are equal. Minor ulcers, the most common type, measure less than 10 millimeters across. You’ll typically have one to five at a time, and they heal within 10 to 14 days without scarring.
Major ulcers are larger than 10 millimeters and can persist for up to six weeks. These sometimes leave scars and are significantly more painful. Herpetiform ulcers (despite the name, unrelated to herpes) appear as clusters of 10 to 100 tiny sores that can merge into larger irregular shapes. Both major and herpetiform types may need prescription treatment, such as a corticosteroid rinse or paste, to manage effectively.
Signs a Mouth Ulcer Needs Professional Attention
Any mouth ulcer lasting longer than two weeks should be evaluated by a dentist or doctor. A two-week threshold is clinically significant because persistent ulcers can occasionally be an early sign of oral cancer or a systemic condition. Ulcers accompanied by high fever, difficulty swallowing, or new sores appearing before old ones heal also warrant a visit. If you notice ulcers that keep recurring in the same spot, or one that’s growing rather than shrinking after a week, get it checked. A biopsy or blood work can rule out anything serious and identify treatable underlying causes like nutritional deficiencies or autoimmune conditions.