Most canker sores heal on their own within one to two weeks, so the goal is managing pain and avoiding anything that makes them worse while your mouth repairs itself. A few simple home remedies can cut the discomfort significantly, and for stubborn or severe sores, stronger options exist.
Rinses and Pastes You Can Make at Home
A saltwater rinse is the simplest first step. Mix about half a teaspoon of salt into a cup of warm water, swish it around the sore for 30 seconds, and spit. This draws fluid out of the inflamed tissue, which temporarily reduces swelling and pain. You can repeat this several times a day, especially after meals when food debris irritates the sore.
Baking soda works similarly. You can either add a teaspoon to warm water for a rinse or mix a small amount with a few drops of water to form a paste and dab it directly on the sore. The paste creates a mildly alkaline environment that helps neutralize acids in your mouth, which are a major source of the stinging sensation.
Honey applied directly to the sore can also soothe pain and may support healing. A thin layer a few times a day is enough. Ice chips or cold water held against the sore will numb the area temporarily if you need quick relief before eating.
Over-the-Counter Products That Help
Numbing gels and patches containing benzocaine are widely available at pharmacies and provide targeted pain relief. You apply the gel directly to the sore, and it numbs the surface for anywhere from 15 minutes to an hour depending on the product. These are especially useful right before meals.
Protective pastes create a barrier over the sore so food, drinks, and your teeth don’t irritate it further. Some combine a numbing agent with the barrier, giving you both pain relief and physical protection. Hydrogen peroxide rinses (diluted to half strength with water) can also help keep the area clean and reduce bacteria around the ulcer.
What to Avoid While You’re Healing
Acidic foods and drinks are the biggest offenders. Citrus fruits, tomatoes, coffee, and vinegar-based dressings will sting on contact and can slow healing. Spicy food, crunchy chips, and crusty bread physically scrape the sore and extend your recovery time. Stick to softer, blander foods until the sore closes up. Lukewarm or cool temperatures are easier on the tissue than anything very hot.
When a Canker Sore Needs Medical Attention
The typical canker sore is under a centimeter across and heals within 7 to 14 days without treatment. But canker sores actually come in three types, and knowing which one you have helps set expectations. Minor sores, the most common kind, are small and resolve within two weeks. Major sores are larger than a centimeter (roughly the size of a pea or bigger) and can linger for up to six weeks. Herpetiform sores are clusters of tiny ulcers, each only 1 to 3 millimeters, that also heal within about two weeks.
Contact a healthcare provider if your sores last longer than two weeks, are larger than a centimeter, come with fever or flu-like symptoms, interfere with eating or drinking, or keep returning two or three times a year. Recurring canker sores can sometimes signal an underlying condition like celiac disease or inflammatory bowel disease, where the immune system’s dysfunction triggers frequent oral ulcers.
Prescription Options for Severe Sores
For sores that don’t respond to home care, a few clinical treatments can help. A prescription mouth rinse containing a steroid or a numbing agent reduces inflammation and pain more effectively than over-the-counter products.
Chemical cauterization is another option. A topical solution called Debacterol contains compounds that essentially seal the ulcer’s surface. You or your dentist applies the swab to the dried sore for 5 to 10 seconds. It stings immediately, but after rinsing with water, the pain from both the treatment and the sore itself fades almost right away. One application is typically enough, and it can reduce healing time to about a week. Silver nitrate, another cauterizing agent, won’t speed healing but does relieve pain.
Oral steroids are reserved as a last resort for severe, recurring sores that resist everything else.
Preventing Future Canker Sores
Canker sores don’t have a single known cause, but several triggers are well established. One of the most common and most overlooked is sodium lauryl sulfate (SLS), the foaming agent in most toothpastes. It’s not necessary for cleaning your teeth, and switching to an SLS-free toothpaste reduces flare-ups for many people who get frequent sores. Brands like Sensodyne, Biotene, and several others make SLS-free versions that are easy to find.
Nutritional gaps also play a role. Zinc deficiency is a recognized trigger, and a simple supplement may help if your diet is low in zinc-rich foods like meat, shellfish, seeds, and legumes. Deficiencies in B vitamins, iron, and folate have also been linked to recurrent canker sores, so a general multivitamin can be worth trying if you notice a pattern.
Mechanical trauma is another frequent culprit. Biting the inside of your cheek, aggressive brushing, orthodontic wires, or ill-fitting dentures can all kick off a sore. Using a soft-bristled toothbrush and being careful during brushing around sensitive tissue helps. Stress is a well-known trigger too, though harder to control. Many people notice sores appearing during high-stress periods like exams, deadlines, or illness.
Canker Sores vs. Cold Sores
These two get confused constantly, but they’re completely different. Canker sores form inside the mouth, on the inner cheeks, lips, tongue, or gums. They appear as white or yellow open ulcers with a red border. They are not contagious and are not caused by a virus.
Cold sores (fever blisters) form outside the mouth, typically around the border of the lips. They’re caused by the herpes simplex virus (usually HSV-1) and are highly contagious. If your sore is on the outside of your lip and started as a fluid-filled blister, it’s a cold sore, not a canker sore, and the treatment approach is different.