Most canker sores heal on their own within 10 to 14 days, but the right combination of pain relief and oral care can make that wait far more bearable and may speed things along. Minor canker sores, the kind most people get, don’t leave scars. Major ones (roughly 1 cm or larger) can take up to six weeks to heal and sometimes scar. Here’s what actually works to manage them and reduce how often they come back.
Rinses You Can Make at Home
A saltwater rinse is the simplest first step. Dissolve about half a teaspoon of salt in a cup of warm water, swish it around your mouth for 30 seconds, and spit. You can do this several times a day. It won’t taste great, but salt draws fluid out of the inflamed tissue, which temporarily reduces swelling and pain.
Baking soda works similarly. Mix one teaspoon into half a cup of warm water and use it as a rinse. Baking soda neutralizes acids in your mouth that irritate the open sore, creating a less hostile environment for healing. A hydrogen peroxide rinse (equal parts 3% peroxide and water) is another option that helps keep the area clean.
Over-the-Counter Treatments
If home rinses aren’t enough, pharmacy products with numbing agents can take the edge off. Look for gels or pastes containing benzocaine, sold under names like Anbesol, Orabase, and Zilactin-B. These create a temporary barrier over the sore and numb the area on contact. Apply them directly to the ulcer as soon as it appears, and reapply as the product label directs, typically before meals.
Milk of magnesia is another surprisingly effective option. Dab a small amount on the canker sore a few times a day. It coats the surface and may reduce irritation from food and saliva.
For a more aggressive approach, a topical solution called Debacterol chemically cauterizes the sore, essentially sealing it. Silver nitrate does something similar, though studies haven’t shown it speeds healing. It can, however, reduce pain significantly after application.
When Prescription Treatment Helps
Canker sores that are especially large, painful, or numerous sometimes need prescription-strength treatment. A dentist or doctor can prescribe a steroid mouth rinse that reduces inflammation throughout your mouth, which is useful when you have multiple sores at once. Prescription-strength topical steroids applied directly to the ulcer are another step up from what’s available over the counter. These suppress the immune response at the sore site, which calms the inflammation driving the pain.
A prescription numbing rinse can also help if eating has become difficult. These options are worth asking about if you’re dealing with sores that keep you from eating normally or that haven’t started improving after a week.
What Triggers Canker Sores
Understanding what sets them off is half the battle for people who get them repeatedly. Common triggers include:
- Mouth injuries: biting your cheek, aggressive brushing, or dental work
- Acidic or spicy foods: citrus fruits, tomatoes, and hot peppers are frequent culprits
- Stress: emotional stress is one of the most reliable triggers
- Toothpaste with SLS: sodium lauryl sulfate, the foaming agent in most major toothpaste brands, is a known soft tissue irritant (more on this below)
- Nutritional gaps: deficiencies in vitamin B12, iron, and folate are all linked to recurrent mouth ulcers
Switch Your Toothpaste
Sodium lauryl sulfate (SLS) is the ingredient that makes your toothpaste foam. It’s also found in shampoo, soap, and household cleaners, which gives you a sense of how harsh it can be on delicate tissue. SLS strips away the protective mucus layer inside your mouth, leaving the tissue underneath more vulnerable to damage and ulceration.
If you get canker sores regularly, switching to an SLS-free toothpaste is one of the easiest changes you can make. Brands like Sensodyne, Biotene, and some versions of Tom’s of Maine skip SLS entirely. Many people who make the switch notice a clear drop in how often sores appear.
Nutritional Deficiencies to Check
Recurrent canker sores can be a sign your body is low on certain nutrients. Vitamin B12 is the most studied connection. Mouth ulcers on the gums or tongue are a recognized symptom of B12 deficiency, and the recommended daily intake for adults is 2.4 micrograms. People who eat little or no animal products are at higher risk, since B12 is found primarily in meat, fish, eggs, and dairy.
Iron and folate deficiencies also show up in people with frequent canker sores. A simple blood test can check all three levels. If a deficiency is confirmed, correcting it with diet or supplements often reduces how often sores return, sometimes dramatically.
What to Avoid While You Have One
You can’t always speed up healing, but you can stop slowing it down. Avoid crunchy foods like chips and crusty bread that physically scrape the sore. Skip acidic drinks like orange juice, lemonade, and coffee, which sting and prolong irritation. Spicy food does the same. Stick to softer, blander foods until the sore is clearly shrinking.
Use a soft-bristled toothbrush and brush gently around the affected area. Vigorous brushing re-injures the tissue and resets the healing clock. If your sore is in a spot your toothbrush keeps hitting, consider using a rinse temporarily in place of brushing that area.
Signs a Canker Sore Needs Medical Attention
Most canker sores are annoying but harmless. A sore that lasts longer than two weeks without improving, or one that’s unusually large, warrants a visit to your doctor or dentist. The same goes for sores that come with a high fever, sores that spread rapidly, or pain so severe that you can’t drink enough fluids. Persistent or unusually frequent canker sores can occasionally signal an underlying condition like celiac disease or an immune disorder that’s worth investigating.