Most mouth ulcers heal on their own within one to two weeks, but you can speed that process and cut the pain significantly with a few straightforward strategies. The key is reducing irritation, keeping the area clean, and giving your body the nutritional support it needs to repair the tissue.
What Type of Ulcer You’re Dealing With
The vast majority of mouth ulcers are aphthous ulcers, commonly called canker sores. They come in three forms. Minor aphthae are the most common: small (under 1 cm), shallow sores on the inner cheeks, lips, or floor of the mouth. They can appear alone or in clusters and typically heal without scarring. Major aphthae are larger, deeper, and more painful. These can take weeks to resolve and sometimes leave a scar. Herpetiform ulcers show up as many tiny, blister-like sores that may merge together.
Knowing which type you have helps set realistic expectations. A single small canker sore should clear up in 7 to 10 days. A larger or deeper ulcer may take three to four weeks, and that’s still within the normal range.
Salt Water and Baking Soda Rinses
The simplest home treatment is a rinse. Dissolve one teaspoon of baking soda in half a cup of warm water and swish it around your mouth for 30 seconds, then spit. You can also use a basic salt water rinse at a similar ratio. Do this several times a day, especially after meals. The rinse helps neutralize acids in your mouth, cleans debris away from the ulcer, and creates an environment where healing happens faster. It will sting briefly on contact, but the pain relief afterward is noticeable.
Over-the-Counter Gels and Rinses
Pharmacy shelves offer two main categories of products for mouth ulcers: numbing agents and protective barriers. Numbing gels containing benzocaine temporarily dull pain at the site. Barrier-type products work differently. They adhere to the surface of the ulcer and form a protective coating over exposed nerve endings, which reduces pain and shields the sore from further irritation while you eat or drink.
Antiseptic mouthwashes containing chlorhexidine can also help. They reduce the severity and pain of existing ulcers, though they won’t prevent new ones from forming. If you use a chlorhexidine rinse, be aware it can temporarily stain teeth with prolonged use.
Switch to an SLS-Free Toothpaste
Sodium lauryl sulfate (SLS) is the foaming agent in most toothpastes, and it’s a well-documented irritant for people prone to canker sores. A systematic review published through 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. The reduction was statistically significant across multiple measures.
SLS-free toothpastes are widely available at pharmacies and grocery stores. If you get mouth ulcers more than a few times a year, this is one of the easiest changes you can make. Look at the ingredient list on the back of the tube and avoid anything listing sodium lauryl sulfate.
Foods That Help and Hurt
What you eat while you have an ulcer matters more than most people realize. Citrus fruits, tomatoes, strawberries, alcohol, fizzy drinks, and spicy or very salty foods all irritate the lining of your mouth and can worsen existing sores or trigger new ones. Even foods you wouldn’t think of as acidic, like strawberries and tomatoes, are common culprits.
Texture also plays a role. Hard, crunchy, or sharp-edged foods like crusty bread, chips, and crackers scrape against the ulcer every time you chew. While your mouth is healing, stick to softer foods: yogurt, scrambled eggs, soups, bananas, and well-cooked grains. Cold foods like smoothies or ice cream can also provide temporary numbing relief.
Check for Nutritional Gaps
Recurring mouth ulcers are one of the recognized symptoms of vitamin B12 deficiency, folate deficiency, and iron deficiency. If you’re getting canker sores frequently, especially in clusters, it’s worth looking at your diet. Foods rich in B12 include meat, fish, dairy, and fortified cereals. Folate comes from leafy greens, beans, and citrus. Iron is found in red meat, lentils, spinach, and fortified grains.
A simple blood test can confirm whether a deficiency is driving your ulcers. Correcting the deficiency often reduces how often they return.
Dealing With Braces or Sharp Teeth
If your ulcers keep forming in the same spot, the cause is likely mechanical: a bracket, wire, rough tooth edge, or ill-fitting denture rubbing against your cheek or tongue. Orthodontic wax is the quickest fix. Warm a small piece between your fingers, then press it over the bracket or wire that’s causing the problem. Make sure the area is dry first so the wax sticks. Silicone covers designed to fit over braces are another option and tend to stay in place longer.
If a sharp or chipped tooth is the source, no amount of wax will solve it permanently. You’ll need the edge smoothed down by a dentist.
Prescription Options for Severe Ulcers
When ulcers are large, deeply painful, or keep coming back, prescription-strength treatments can help. The most common approach is a steroid mouthwash. You swish a measured amount around your mouth for several minutes, then spit it out. You avoid eating or drinking for about 15 minutes afterward so the medication stays in contact with the tissue. These rinses reduce inflammation and can dramatically shorten healing time for major ulcers.
Some dentists and oral medicine specialists also offer low-level laser therapy, which uses targeted light energy to accelerate tissue repair. Research in animal models has shown significantly faster wound closure with laser treatment, particularly by day seven. In clinical practice, many patients report immediate pain reduction after a single session. This option is more commonly available at university dental clinics and specialist practices.
When an Ulcer Needs Professional Attention
Any mouth ulcer that hasn’t healed after two to three weeks deserves a professional evaluation. This is sometimes called the “two to three week rule” in oral medicine, and it exists because persistent ulcers can occasionally signal oral cancer or other serious conditions. Other warning signs include an ulcer that keeps growing, one that bleeds easily, unexplained numbness, or a lump in your neck. A painless ulcer that won’t heal is actually more concerning than a painful one, since canker sores almost always hurt.
Ulcers that keep returning in cycles, several times a year or more, also warrant investigation. Conditions like celiac disease, inflammatory bowel disease, and immune disorders can all cause recurrent oral ulceration. Identifying and treating the underlying condition is the only way to break the cycle in those cases.