Most canker sores heal on their own within one to two weeks without any treatment. But if you’re dealing with one right now, you probably want to speed that up or at least reduce the pain while you wait. The good news is that a combination of simple home remedies, smart food choices, and over-the-counter products can make a real difference in how quickly and comfortably you get through it.
What You’re Dealing With
Canker sores appear inside the mouth, usually on the inner cheeks, lips, or tongue. They’re typically round, white or yellow in the center, and ringed with red. Unlike cold sores, which show up as clusters of fluid-filled blisters on the outside of the lips and are caused by the herpes virus, canker sores are not contagious and have no confirmed single cause.
Common triggers include mouth injuries (biting your cheek, a sharp chip scraping your gum), stress, smoking, and deficiencies in iron, vitamin B12, or folic acid. That’s worth knowing because understanding your triggers is part of preventing the next one.
How Long Healing Takes
Not all canker sores are the same size, and size largely determines how long you’ll be dealing with one.
- Minor canker sores are the most common type, smaller than a pea (under one centimeter). These heal within a few weeks and don’t leave scars.
- Major canker sores are larger than one centimeter, extremely painful, and can take months to fully heal. They often leave scars behind.
- Herpetiform canker sores are rare. They appear as clusters of tiny pinpoint sores and typically heal within about two weeks without scarring.
If your sore is small and you just got it, you’re likely looking at 7 to 14 days. The strategies below can help you stay comfortable through that window and potentially shorten it.
Home Remedies That Help
A saltwater rinse is the simplest and most widely recommended home treatment. Mix about half a teaspoon of salt into a cup of warm water, swish it around your mouth for 30 seconds, and spit. This helps keep the area clean and can reduce inflammation. You can do this several times a day, especially after meals.
A baking soda rinse works similarly. Dissolve about a teaspoon of baking soda in half a cup of warm water and swish. Baking soda helps neutralize acids in the mouth that irritate the sore. Some people alternate between salt and baking soda rinses throughout the day.
Applying a small amount of milk of magnesia directly to the sore a few times daily can also coat and soothe it. Placing a damp tea bag (black tea works well, since it contains tannins that have a mild astringent effect) against the sore for a few minutes is another option. The goal with all of these is the same: reduce irritation, manage pain, and let your body do the healing.
Over-the-Counter Products
For pain relief, look for topical gels or pastes containing a numbing agent like benzocaine. These are applied directly to the sore and provide temporary relief, which is especially helpful before meals. Oral pain relievers containing a numbing rinse can also work if you have sores in hard-to-reach spots.
Protective pastes that form a barrier over the sore are another good option. They shield the ulcer from food, drinks, and your teeth, reducing irritation throughout the day. You’ll find these at most pharmacies near the dental care products.
One thing that won’t help: chemical cautery treatments like silver nitrate sticks. While they may seem like they’d speed healing by “burning off” the sore, research from the University of Iowa’s head and neck protocols notes that cautery agents don’t actually change the course of the disease. They may reduce pain briefly by destroying nerve endings at the surface, but they won’t get you healed faster.
Foods to Avoid While Healing
What you eat matters more than you might think when you have an active sore. Acidic and abrasive foods can re-irritate the ulcer every time you eat, effectively resetting your healing progress. While you’re waiting for the sore to close up, steer clear of these:
- Citrus fruits and juices: oranges, grapefruits, lemons, limes, pineapple
- Tomatoes and tomato-based foods: marinara sauce, pizza, tomato soup
- Coffee and soda: both are highly acidic, and diet soda is just as bad as regular
- Spicy foods: hot peppers and heavy spices irritate exposed tissue
- Crunchy or sharp foods: chips, pretzels, nuts, and anything that could physically scrape the sore
Stick to soft, mild foods while you heal. Yogurt, oatmeal, scrambled eggs, bananas, and smoothies are all easy on a sore mouth. Cool or room-temperature foods tend to feel better than anything very hot.
Switch Your Toothpaste
If you get canker sores frequently, your toothpaste may be part of the problem. Sodium lauryl sulfate (SLS), the ingredient that makes toothpaste foamy, has been linked to canker sore outbreaks in multiple studies. In a 2012 clinical trial, 90 participants who used SLS-free toothpaste for eight weeks reported that their canker sores didn’t last as long and caused less pain compared to periods when they used SLS-containing toothpaste. Other research has found that switching to an SLS-free formula reduced how often sores appeared in the first place.
Check your toothpaste’s ingredient list for “sodium lauryl sulfate.” If it’s there, try an SLS-free alternative for a few months and see if your outbreak frequency drops. Several major brands now sell SLS-free versions.
Nutritional Deficiencies and Recurring Sores
A single canker sore is usually just bad luck, a stray bite, or a stressful week. But if you keep getting them, a nutritional deficiency could be the underlying cause. Canker sores are frequently linked to low levels of iron, vitamin B12, and folic acid. In one study, roughly 28% of patients with recurring mouth ulcers were deficient in one or more B vitamins, including B1 (thiamine), B2 (riboflavin), and B6 (pyridoxine).
If you’re dealing with sores that come back every few weeks, it’s worth looking at your diet. Foods rich in B vitamins include whole grains, eggs, dairy, legumes, and leafy greens. Iron-rich foods include red meat, spinach, lentils, and fortified cereals. A healthcare provider can run a simple blood test to check your levels and recommend supplements if needed.
Signs a Canker Sore Needs Medical Attention
Most canker sores are annoying but harmless. However, you should get a sore looked at if it’s unusually large (bigger than a centimeter across), lasts longer than three weeks, keeps coming back in clusters, makes it too painful to eat or drink, or is accompanied by fever. A sore that won’t heal could occasionally signal something other than a simple canker sore, and a dentist or doctor can rule out other causes quickly.
For major canker sores that are severe or persistent, a healthcare provider may prescribe a medicated mouth rinse or a stronger topical treatment to bring down inflammation and pain. These prescription options are generally reserved for sores that aren’t responding to the home and over-the-counter approaches described above.