Most mouth ulcers heal on their own within 10 to 14 days. You can’t dramatically speed up that timeline, but you can reduce pain, avoid making the ulcer worse, and create conditions that let your mouth heal without setbacks. If you’re dealing with recurring ulcers, there are also specific changes that can reduce how often they come back.
What Actually Helps an Ulcer Heal
The most effective thing you can do is remove whatever is irritating the ulcer and keep the area clean. That means a simple rinse several times a day, especially after meals. St. Jude Children’s Research Hospital recommends an alkaline saline solution: 1 teaspoon of salt and 1 teaspoon of baking soda dissolved in 4 cups of warm water. The salt helps draw fluid from inflamed tissue, and the baking soda raises the pH in your mouth, creating a less hospitable environment for bacteria. Swish gently for 30 seconds and spit. Repeat three or four times a day.
Over-the-counter gels containing benzocaine (typically at 20%) numb the surface of the ulcer and can make eating bearable. Some products also include zinc chloride, an astringent that helps dry out and protect the sore. These don’t shorten healing time in a meaningful way, but they manage pain well enough to get you through meals and conversation. Apply directly to the ulcer with a clean finger or cotton swab.
Foods That Make Ulcers Worse
Acidic foods and drinks lower the pH inside your mouth, which breaks down the protective proteins on your oral tissue. The obvious offenders are citrus fruits, fizzy drinks, and alcohol. Less obvious ones include strawberries and tomatoes, both of which are acidic enough to irritate an open ulcer. Spicy and salty foods directly aggravate the exposed tissue as well.
Texture matters just as much as chemistry. Hard, crunchy, or sharp-edged foods like toast, chips, and crusty bread can physically scrape the ulcer and reopen healing tissue. While you’re waiting for an ulcer to close, stick to softer foods. Drinking cool beverages through a straw can help liquids bypass the sore entirely.
Switch to an SLS-Free Toothpaste
Sodium lauryl sulfate (SLS) is a foaming agent in most standard toothpastes, and it’s one of the most well-documented triggers for recurrent mouth ulcers. A systematic review highlighted by the American Dental Association found that switching to an SLS-free toothpaste resulted in fewer ulcers, shorter ulcer duration, fewer recurring episodes, and less pain. One pooled analysis showed a statistically significant reduction of roughly one fewer ulcer per cycle when patients dropped SLS from their routine.
If you get mouth ulcers more than a few times a year, this is one of the simplest changes you can make. SLS-free toothpastes are widely available and don’t cost more than standard options. You’ll also want to use a soft-bristled toothbrush, since aggressive brushing with stiff bristles can damage the delicate lining of your mouth and trigger new ulcers.
Why Some People Get Ulcers Repeatedly
Recurrent ulcers often point to an underlying factor rather than just bad luck. The most common contributors are nutritional deficiencies, particularly low iron, low vitamin B12, and low folic acid. In a study of 273 patients with recurrent aphthous ulcers, about 20% were anemic, 20% had low iron, and smaller but significant percentages were deficient in B12 or folic acid. If your ulcers keep coming back, it’s worth having blood work done to check these levels.
Stress, fatigue, and hormonal shifts also play a role. The lining of your mouth is one of the fastest-turning-over tissues in your body, and it’s sensitive to systemic changes. Mechanical causes are common too: a sharp edge on a filling, poorly fitting braces or dentures, or habitually biting the inside of your cheek can create ulcers in the same spot over and over. A dental checkup can identify and fix these kinds of structural irritants.
Preventing the Next One
The NHS recommends a straightforward set of habits to reduce ulcer frequency:
- Use a soft-bristled toothbrush and brush gently along the gumline
- Avoid SLS-containing toothpaste
- Limit acidic, spicy, and salty foods if you notice they trigger outbreaks
- Eat a balanced diet with adequate iron, B12, and folate (leafy greens, eggs, legumes, fortified cereals)
- Manage stress through sleep, exercise, or whatever works for you
- Get regular dental checkups to catch rough fillings or sharp tooth edges early
If you notice a pattern, like ulcers appearing after eating certain foods, you may be dealing with a food sensitivity. Keeping a brief log of what you ate in the days before an outbreak can help you identify personal triggers.
When an Ulcer Needs Professional Attention
A single mouth ulcer that heals within two weeks is almost always harmless. The critical threshold is duration: any oral ulcer lasting longer than two weeks should be evaluated by a dentist or doctor. Clinical referral guidelines use this two-week mark specifically because persistent ulcers can, in rare cases, signal oral cancer or other conditions that need treatment. Ulcers that are unusually large (bigger than a centimeter), extremely painful, spreading, or accompanied by fever also warrant a visit. The same goes for ulcers that keep returning to the exact same spot, which could indicate a structural problem with a tooth or restoration pressing into the tissue.