Most canker sores heal on their own within two weeks, but you can speed up recovery and cut the pain significantly with a few simple steps. The key is reducing irritation, keeping the area clean, and using the right topical products early.
What a Canker Sore Actually Is
A canker sore is a small, round ulcer that forms inside your mouth, typically on the inner cheeks, lips, tongue, or soft palate. It usually appears as a single white or yellow spot with a red border. This is not the same thing as a cold sore: cold sores are clusters of fluid-filled blisters that show up outside the mouth, around the lips, and are caused by a virus. Canker sores are not contagious.
The exact cause isn’t fully understood, but the immune system plays a central role. In people who are prone to them, immune cells attack the lining of the mouth, breaking down tissue and creating the ulcer. About one-third of people with recurrent canker sores have a family history of them, suggesting a genetic component. Common triggers include biting your cheek, stress (outbreaks spike during exam periods, for example), hormonal shifts during the menstrual cycle, food sensitivities, and even quitting smoking.
Home Remedies That Actually Help
A saltwater rinse is the simplest and most accessible option. Dissolve about half a teaspoon of salt in a cup of warm water and swish gently for 30 seconds, then spit. This draws fluid out of the sore, which can reduce swelling, and it helps keep the area clean. You can repeat this several times a day. It will sting briefly, but the relief afterward is worth it.
Baking soda works similarly. Mix a teaspoon into a half cup of warm water for a rinse, or make a paste with a few drops of water and apply it directly to the sore. Baking soda neutralizes acids in the mouth that can irritate the ulcer.
Milk of magnesia is another option you likely already have at home. Dab a small amount directly onto the canker sore a few times a day. It coats the ulcer and helps neutralize the acidic environment around it, which reduces pain and may promote faster healing.
Honey has natural antibacterial and anti-inflammatory properties. Applying a thin layer of raw honey to the sore several times a day can reduce pain and size. Just avoid flavored or processed honey, which may contain irritants.
Over-the-Counter Products Worth Trying
If home remedies aren’t giving you enough relief, OTC products designed for mouth sores can make a noticeable difference, especially when you apply them as soon as the sore appears. Look for products in paste, gel, or liquid form that contain one of these active ingredients:
- Benzocaine (found in Anbesol, Orabase, Zilactin-B): a numbing agent that temporarily blocks pain on contact. Apply directly to the sore before meals for easier eating.
- Hydrogen peroxide rinses (such as Peroxyl): antiseptic rinses that clean the sore and reduce bacteria in the surrounding tissue. Use a diluted formula designed for oral use, not the brown bottle from your medicine cabinet.
Protective pastes and gels that form a barrier over the ulcer are particularly useful. They shield the sore from food, drinks, and your teeth, which prevents the repeated irritation that slows healing. Apply after eating and before bed for the best coverage.
Foods and Habits to Avoid
What you don’t do matters as much as what you do. Acidic foods like citrus fruits, tomatoes, and vinegar-based dressings directly irritate the exposed tissue and can make a canker sore dramatically more painful. Spicy foods, salty snacks, and rough-textured items like chips or crusty bread can physically abrade the ulcer and delay healing.
Check your toothpaste label. Sodium lauryl sulfate (SLS), the foaming agent in many toothpastes, can aggravate canker sores in some people. Switching to an SLS-free toothpaste may reduce irritation while you have an active sore and could lower the frequency of future outbreaks if you’re prone to them. Several major brands sell SLS-free versions.
Try not to poke at the sore with your tongue. It’s tempting, but repeated contact slows the healing process.
Nutritional Gaps That Fuel Recurrence
If you get canker sores frequently, a nutritional deficiency could be part of the picture. In a study of 273 people with recurrent canker sores, about 20% were deficient in iron, nearly 5% were low in vitamin B12, and close to 3% had a folic acid deficiency. About 21% had anemia. These nutrients are all involved in maintaining healthy mucosal tissue and immune function.
You don’t necessarily need supplements. Eating more leafy greens, legumes, eggs, and fortified cereals can fill these gaps for most people. But if your sores keep coming back despite good oral care, it’s worth asking for a blood test to check your levels of B12, iron, and folate.
How Long Healing Takes
Minor canker sores, the most common type, are smaller than a centimeter across and typically heal within two weeks without leaving a scar. Most of the pain peaks in the first three to four days and then gradually fades.
Major canker sores are larger than a centimeter, significantly more painful, and can take months to fully heal. They sometimes leave scarring. A third, rarer type called herpetiform canker sores appear as clusters of tiny pinpoint ulcers. Despite the name, they’re not caused by the herpes virus. These clusters usually heal within about two weeks without scarring.
When a Mouth Sore Needs Attention
A canker sore that hasn’t healed after two weeks deserves a closer look. A sore that persists beyond that window, keeps growing, or comes with unusual symptoms like difficulty swallowing, loose teeth, ear pain, or a lump in the mouth should be evaluated by a dentist or doctor. These can occasionally be signs of a more serious condition, including oral cancer. A white or reddish patch inside the mouth that doesn’t resolve is another signal worth getting checked.
Recurrent canker sores, meaning you get several outbreaks a year with little relief between them, can sometimes be managed with prescription-strength treatments. These include topical anti-inflammatory gels and medicated mouth rinses that reduce immune activity at the site of the ulcer. Your dentist or doctor can determine whether your pattern of sores warrants this level of treatment.