Most mouth ulcers heal on their own within one to two weeks, but the right home care can cut down pain significantly and speed that timeline along. The key is combining a good rinse routine with smart food choices and protecting the sore from further irritation while it closes up.
Rinses That Reduce Pain and Inflammation
A simple saltwater or baking soda rinse is the most reliable first step. For a baking soda rinse, dissolve 1 teaspoon of baking soda in half a cup of warm water, swish gently for 15 to 30 seconds, and spit. You can do this several times a day. For a saltwater rinse, use roughly the same ratio: about 1 teaspoon of salt in half a cup of warm water. Both options help keep the area clean and create an environment that’s less hospitable to bacteria, which lets the ulcer heal without complications.
If rinsing alone isn’t enough, a diluted hydrogen peroxide solution (equal parts 3% hydrogen peroxide and water) applied with a cotton swab can help disinfect the sore. Don’t swallow it, and don’t use it more than a few times a day.
Over-the-Counter Numbing Products
Benzocaine gels, sprays, and ointments are available at most pharmacies and temporarily numb the ulcer on contact. Apply directly to the sore up to four times a day. These products are suitable for adults and children over age 2, but shouldn’t be used for more than two days in a row without guidance from a healthcare provider. They’re especially useful right before meals, since eating is often the most painful part of having a mouth ulcer.
Protecting the Ulcer While It Heals
What you eat matters more than you might expect. Spicy foods, citrus fruits, tomatoes, and anything with sharp edges (chips, crusty bread, hard crackers) can re-irritate the ulcer and drag out healing. Stick to soft foods and cool or room-temperature drinks. Using a straw can help liquids bypass the sore entirely.
If you notice that certain foods seem to trigger new ulcers, not just irritate existing ones, keep a mental note. Common culprits include citrus, chocolate, coffee, and very salty snacks. Avoiding your personal triggers can reduce how often ulcers come back.
Switch to an SLS-Free Toothpaste
Sodium lauryl sulfate (SLS) is a foaming agent found in most toothpastes, and it’s a surprisingly common contributor to recurring mouth ulcers. A meta-analysis of 89 participants found that people who switched to SLS-free toothpaste experienced fewer ulcer episodes, shorter healing times, and less pain compared to those using standard toothpaste. If you get mouth ulcers more than a few times a year, this single change is one of the most evidence-backed things you can do. Several brands sell SLS-free versions, often labeled as “gentle” or “sensitive” formulas.
Alum Powder as a Spot Treatment
Alum powder, the same astringent used in pickling, is a traditional remedy that some people find effective. Mix a tiny amount of the powder with a single drop of water to form a paste, dab it directly onto the ulcer, and leave it for at least one minute before rinsing your mouth thoroughly. You can repeat this once daily until the sore heals. The astringent action helps shrink the tissue and may reduce pain. That said, clinical research on alum for mouth ulcers is limited, so treat it as a supplementary option rather than a primary one.
Nutritional Gaps That Fuel Recurring Ulcers
If your ulcers keep coming back, the problem may not be local, it may be nutritional. Vitamin B12 deficiency is one of the most well-documented nutritional causes of recurrent oral ulcers. Iron deficiency is another common one, particularly in people who also notice a smooth or sore tongue. Low levels of zinc, folate, and vitamin D have also been linked to recurring oral sores.
You don’t necessarily need to start taking supplements blindly. A simple blood test can check for these deficiencies, and correcting a confirmed deficiency often reduces or eliminates ulcer recurrence. In the meantime, foods rich in B12 (meat, eggs, dairy, fortified cereals), iron (red meat, spinach, lentils), and zinc (shellfish, seeds, nuts) can help shore up your intake.
Signs Your Ulcer Needs Professional Attention
Most mouth ulcers resolve within two weeks. According to Cleveland Clinic guidelines, you should contact a healthcare provider if a mouth sore lasts three weeks or longer, if new sores keep appearing before old ones heal, if an ulcer is unusually large, or if it’s painless (painless sores can occasionally signal something other than a standard canker sore). Fever, diarrhea accompanying mouth sores, or ulcers that appear on the outer part of your lips rather than inside the mouth also warrant a professional evaluation.