Most mouth ulcers heal on their own within 10 days, but you can speed things along and reduce pain with a few straightforward strategies. These small, round sores (often called canker sores) appear on the inner cheeks, lips, tongue, or floor of the mouth, and while they’re rarely dangerous, they can make eating and talking miserable.
What Type of Ulcer You’re Dealing With
The most common variety, minor aphthous ulcers, are typically 2 to 3 mm across and heal within about 10 days without scarring. These are what most people are searching about. Major aphthous ulcers are larger than 1 cm, deeper, and can take weeks or even months to fully heal. A third type, herpetiform ulcers, show up as clusters of dozens of tiny sores that merge into larger patches, usually resolving in about two weeks.
Mouth ulcers are not the same as cold sores. Cold sores (fever blisters) appear outside the mouth, usually around the lip border, as clusters of small fluid-filled blisters. They’re caused by a virus and are contagious. Canker sores appear inside the mouth as single round white or yellow sores with a red border. They’re not contagious and not caused by a virus.
Saltwater and Baking Soda Rinses
A simple rinse is the most accessible home treatment and one of the most effective for keeping the area clean while it heals. St. Jude Children’s Research Hospital recommends this ratio: 1 teaspoon of table salt and 1 teaspoon of baking soda dissolved in 4 cups of warm water. The alkaline solution helps neutralize mouth acid, reduces irritation, and creates an environment that discourages infection. Swish gently for 30 seconds a few times a day, especially after meals.
Over-the-Counter Pain Relief
Topical gels and pastes containing numbing agents like benzocaine can take the edge off pain before meals. You apply them directly to the ulcer, where they form a temporary protective barrier. Prescription-strength steroid pastes work by reducing inflammation at the ulcer site and are typically applied after meals and at bedtime to give the medication the longest possible contact time with the sore.
If you’re dealing with significant pain, an over-the-counter oral pain reliever can help while you wait for the ulcer to close up. Avoid mouthwashes that contain alcohol, as they’ll sting and can further irritate the damaged tissue.
Foods That Slow Healing
What you eat matters more than you might expect. Acidic foods and drinks, including citrus fruits, fizzy drinks, and alcohol, lower the pH in your mouth and disrupt the protective layer of tissue, leaving the ulcer more exposed. Strawberries and tomatoes are two common triggers people don’t think of as acidic, but they can aggravate or even provoke ulcers. Spicy and very salty foods irritate the delicate lining of the mouth directly.
While your ulcer is healing, stick to soft, bland foods at moderate temperatures. Yogurt, mashed potatoes, scrambled eggs, and smoothies (skip the citrus) are all easy options. Drinking through a straw can help liquids bypass the sore if it’s on your inner cheek or lip.
Nutritional Deficiencies to Consider
If you get mouth ulcers repeatedly, the problem may not be local irritation but a nutritional gap. Research has found that among people with recurrent ulcers, about 20% are iron deficient and around 21% are anemic. Vitamin B12 deficiency shows up in roughly 5 to 7% of cases, and folic acid deficiency in about 3%. All of these nutrients play roles in maintaining healthy oral tissue, and correcting a deficiency can reduce or eliminate recurring outbreaks. A simple blood test can check your levels.
Preventing the Next One
Some people find that switching to a toothpaste without sodium lauryl sulfate (SLS) reduces their outbreaks. SLS is the foaming agent in most toothpaste, and it acts as a detergent that can disrupt the mouth’s inner lining. The evidence is mixed: one study found SLS-free toothpaste reduced the number, pain, and recurrence of ulcers, while a 2019 review concluded there wasn’t enough data to make a definitive recommendation. Still, if you’re prone to frequent ulcers, trying an SLS-free brand for a few months is a low-risk experiment.
Mechanical trauma is another common trigger. Biting your cheek, brushing too aggressively, or having a rough edge on a tooth or dental appliance can all start an ulcer. Using a soft-bristled toothbrush and getting sharp dental edges filed down can help prevent recurrences. Stress and hormonal changes are also well-recognized triggers, though they’re harder to control.
When an Ulcer Needs Professional Attention
The two-week mark is the key threshold. Most mouth ulcers resolve well before 14 days. If a sore persists for two weeks or longer after any obvious irritant (like a rough tooth edge) has been addressed, clinical guidelines recommend professional evaluation. Persistent oral lesions that are red and white, bleed easily, feel hard or fixed to deeper tissue, or grow rapidly raise concern for something more serious, including oral cancer. An ulcer that keeps coming back in the same spot also warrants a closer look. In these cases, a dentist or doctor may take a small tissue sample to rule out other conditions.