Most mouth sores are canker sores, small round ulcers that form on the inside of your cheeks, lips, or tongue. They typically heal on their own within 10 to 14 days, but you can speed up the process and reduce pain with a few proven strategies. About 85% of mouth sores are the minor type, less than 1 cm across, and respond well to home care.
First, Identify What You’re Dealing With
Canker sores and cold sores are often confused, but they’re completely different problems with different treatments. The simplest way to tell them apart is location. Canker sores appear inside the mouth, usually as a single round white or yellow sore with a red border. Cold sores (fever blisters) appear outside the mouth, typically as a cluster of small fluid-filled blisters around the lips. Cold sores are caused by the herpes simplex virus and are contagious. Canker sores are not contagious and don’t have a single known cause.
If your sore is inside your mouth and looks like a shallow crater with a whitish center, you’re almost certainly dealing with a canker sore. The strategies below are designed for these.
Salt Water and Baking Soda Rinses
A salt water rinse is the simplest and most accessible treatment. Mix 1 teaspoon of salt into 8 ounces of warm water until it dissolves, then swish gently for 30 seconds and spit. If it stings too much, cut the salt to half a teaspoon. You can do this several times a day, especially after meals when food particles may irritate the sore.
Baking soda works well too. You can add 1 teaspoon of baking soda to your salt water rinse for extra benefit, or make a paste by mixing baking soda with a few drops of water until it reaches toothpaste consistency. Apply the paste directly to the sore and let it sit before rinsing. Baking soda helps neutralize acid in the mouth, which reduces irritation to the open tissue.
Over-the-Counter Pain Relief
For sores that make eating or talking painful, numbing gels containing 20% benzocaine provide the fastest relief. To get the best results, dry the sore with a tissue first, then apply the gel directly. It forms a protective film coating over the ulcer that blocks contact with food and saliva. You can reapply up to four times a day.
Hydrogen peroxide rinses (diluted to the concentration on the label) are another option. These help keep the sore clean and reduce bacteria around the wound. Antiseptic mouth rinses designed for oral sores combine mild pain relief with a protective barrier, which can be useful if you have multiple sores at once.
Honey as a Topical Treatment
Honey applied directly to mouth sores has performed well in clinical trials. In one study comparing honey paste to a standard prescription steroid ointment, participants using honey experienced significant reductions in both pain and sore size, with the honey group actually reporting the most substantial pain relief of all groups tested. Use raw or medical-grade honey, apply it to the sore a few times a day, and try not to eat or drink for several minutes afterward so it stays in contact with the tissue.
Foods and Drinks to Avoid
What you eat while you have a mouth sore matters more than most people realize. Acidic foods and drinks lower the pH in your mouth and directly irritate open tissue. The obvious culprits are citrus fruits, fizzy drinks, and alcohol, but strawberries and tomatoes are common triggers that people often overlook.
Spicy and heavily salted foods irritate the delicate lining of the mouth and can delay healing. Texture matters too. Hard, crunchy, or sharp-edged foods like crusty bread, chips, and raw vegetables can physically scrape the sore and make it worse. Stick to soft, cool, or room-temperature foods until the ulcer closes. Yogurt, smoothies, scrambled eggs, and soft pasta are good options.
Switch to SLS-Free Toothpaste
If you get mouth sores repeatedly, your toothpaste may be part of the problem. Sodium lauryl sulfate (SLS) is a foaming agent found in most commercial toothpastes, and it can irritate the mucous membrane inside your mouth. A systematic review of clinical trials found that switching to SLS-free toothpaste significantly reduced the number of ulcers, the duration of each ulcer, the number of episodes, and ulcer pain across all four measures studied. Several brands sell SLS-free options, typically labeled on the packaging. This is one of the easiest changes you can make if canker sores are a recurring issue for you.
Check for Nutritional Deficiencies
Recurring mouth sores are sometimes a sign that your body is low on specific nutrients. The most commonly linked deficiencies are iron, vitamin B12, folic acid, and vitamin C. In documented cases, patients with recurrent canker sores had vitamin B12 levels far below the normal range, sometimes about half of the lower limit of normal. Once the deficiency was corrected, the sores resolved.
If you’re getting canker sores frequently (several times a year or more), it’s worth asking for a blood test to check your iron, B12, and folate levels. This is especially relevant if you follow a vegetarian or vegan diet, have digestive conditions that affect nutrient absorption, or notice other symptoms like fatigue or pale skin.
When Mouth Sores Need Professional Treatment
Most canker sores are small and heal within two weeks without intervention. But about 10 to 15% of people with recurrent sores develop the major type, which exceeds 10 mm in diameter, runs deeper into the tissue, and can last for weeks to months. These larger sores often leave scars and generally need prescription treatment.
For moderate to severe cases, doctors can prescribe topical steroid ointments that reduce inflammation while forming a protective barrier over the ulcer. For widespread sores, a prescription anti-inflammatory rinse can treat multiple ulcers at once. One potential side effect of steroid rinses is fungal infection in the mouth, so these are used under medical supervision.
Another option available in a doctor’s or dentist’s office is chemical cauterization, where the sore is briefly touched with a silver nitrate stick. The procedure stings for a moment, but patients typically walk out pain-free. The chemical seals the nerve endings in the ulcer, providing immediate relief.
Persistent or unusually frequent canker sores can sometimes signal underlying conditions, including celiac disease, immune disorders, or blood-related conditions. If your sores are larger than a centimeter, last longer than two weeks, come back constantly, or are accompanied by fever or other symptoms, a healthcare provider can run bloodwork to rule out systemic causes.
Reducing Flare-Ups Over Time
Canker sores are triggered by a combination of factors, and managing them long-term means identifying your personal triggers. Common ones include physical injury to the mouth (biting your cheek, aggressive brushing, dental work), emotional stress, hormonal changes, and the dietary factors mentioned above. Keeping a simple log of when sores appear and what preceded them can reveal patterns you’d otherwise miss.
For many people, the combination of switching to SLS-free toothpaste, correcting any nutritional gaps, and avoiding known food triggers cuts the frequency of outbreaks dramatically. When sores do appear, starting salt water rinses and topical treatment immediately, rather than waiting a few days, helps them resolve faster.