Most mouth sores heal on their own within one to two weeks, but you can speed up the process and cut the pain significantly with a few simple treatments. The right approach depends on what type of sore you’re dealing with, so it helps to identify it first.
Identify Your Mouth Sore
The two most common types are canker sores and cold sores, and they require different treatment.
Canker sores (aphthous ulcers) appear inside the mouth only, on the inner cheeks, lips, or tongue. They look like a single round white or yellow sore with a red border. They’re not contagious, and their exact cause isn’t known, though stress, mouth injuries, and nutritional deficiencies can trigger them. Minor canker sores typically disappear in about a week. Major ones can take up to four weeks.
Cold sores (fever blisters) form on the outside of the mouth, around the lips. They appear as clusters of small fluid-filled blisters and are caused by the herpes simplex virus (HSV-1). They’re highly contagious. If you have cold sores, the treatments below for canker sores won’t address the underlying virus, and you may benefit from an antiviral medication from your doctor.
The rest of this article focuses primarily on canker sores and general mouth sores inside the mouth, since those are the most common reason people search for relief.
Salt Water Rinse
A warm salt water rinse is the simplest and most effective first step. Salt water promotes healing in oral tissue by encouraging the cells that repair wounds to migrate faster. Mix about one teaspoon of salt (5 grams) into one cup of warm water (250 ml). Swish it gently around the sore for about two minutes, then spit it out. Repeat three times a day, spacing rinses roughly five to six hours apart. It will sting briefly on contact, but the discomfort fades quickly.
Over-the-Counter Pain Relief
Numbing gels containing benzocaine are widely available and provide temporary pain relief directly at the sore. These come in 10 percent (regular strength) and 20 percent (maximum strength) formulations. Both concentrations work, but the 20 percent version provides noticeably more relief. Dab a small amount directly onto the sore with a clean finger or cotton swab. This is especially useful before meals if eating has become painful.
You can also find OTC oral pastes that form a protective barrier over the sore, shielding it from food and saliva while it heals. Some contain mild anti-inflammatory ingredients. Look for products specifically labeled for canker sores or mouth ulcers.
Avoid Foods That Make It Worse
Certain foods and drinks directly irritate an open sore and can delay healing. While the sore is active, limit or avoid:
- Acidic foods like citrus fruits, tomatoes, and vinegar-based dressings
- Spicy foods including hot sauce, chili peppers, and heavily seasoned dishes
- Carbonated beverages which combine acidity with fizz that stings open tissue
- Crunchy or sharp-edged foods like chips and crusty bread that can physically reinjure the sore
Stick to soft, bland, cool foods while you’re healing. Yogurt, oatmeal, scrambled eggs, and smoothies are all gentle options.
Prescription Options for Severe Sores
If your sore is large, extremely painful, or keeps coming back, a doctor or dentist can prescribe a stronger treatment. One common option is a prescription-strength steroid paste that you press onto the sore in a thin film, typically at bedtime and after meals. This reduces inflammation and pain more effectively than anything available over the counter. If the sore hasn’t started improving within seven days of using a prescription paste, follow up with your provider.
Nutritional Gaps That Cause Recurring Sores
If you get canker sores repeatedly, the problem may be nutritional. Research has consistently linked recurrent canker sores to lower intake of vitamin B12, folate, and iron. In one study, people with recurring sores consumed about 20 percent less folate and 7 percent less B12 than the daily recommended amount compared to people without sores. Sometimes, mouth ulcers are the earliest and only visible sign of a B12 or folate deficiency, appearing before other symptoms develop.
Good sources of B12 include meat, fish, eggs, and dairy (or a supplement if you eat a plant-based diet). Folate is found in leafy greens, beans, and fortified grains. If you suspect a deficiency, a simple blood test from your doctor can confirm it. Correcting the deficiency often reduces how frequently sores appear.
Prevent Future Mouth Sores
One surprisingly effective change is switching to a toothpaste that doesn’t contain sodium lauryl sulfate (SLS), the foaming agent in most commercial toothpastes. SLS strips away the protective mucus layer inside your mouth, leaving the tissue underneath more vulnerable to damage. In one study, people who switched to an SLS-free toothpaste saw their number of canker sores drop from an average of about 14 over the study period to just 5. That’s roughly a 65 percent reduction. SLS-free toothpastes are sold at most pharmacies and are usually labeled as such on the packaging.
Other preventive steps include using a soft-bristled toothbrush to avoid scraping the inside of your mouth, managing stress (a known trigger), and being careful not to bite your cheeks or lips while eating.
Signs a Mouth Sore Needs Medical Attention
Any mouth sore that lasts longer than 10 days without improvement should be evaluated by a doctor or dentist to rule out something more serious, including precancerous changes. Seek care sooner if you also have a fever, blisters on your skin, eye inflammation, or if you have a weakened immune system. If the sore is making it too painful to eat or drink, or you feel generally unwell, don’t wait the full 10 days.