Most canker sores on the gums heal on their own within one to three weeks, but you can speed up the process and cut the pain significantly with a few targeted steps. These small, round ulcers with a white or yellow center and red border form on the soft tissue at the base of your gums, and while they’re not contagious or dangerous, they can make eating and brushing miserable.
Salt Water Rinses and Why They Work
The simplest and most effective home remedy is a warm salt water rinse. Salt helps neutralize the acidic environment inside your mouth that keeps the sore inflamed, and a study cited by the National Dental Centre Singapore found that a roughly 7 percent concentration of table salt improved wound healing effectiveness. In practical terms, that’s about half a teaspoon of salt dissolved in four ounces of warm water. Swish it gently around the sore for 15 to 30 seconds, then spit. Repeat two to three times a day, especially after meals.
It will sting for a few seconds. That’s normal. What you should not do is rub salt directly on the ulcer, which can damage the tissue further and slow healing.
Over-the-Counter Pain Relief
Topical gels containing benzocaine numb the sore on contact, creating a window of relief for eating and drinking. Apply a small amount directly to the ulcer with a clean finger or cotton swab. These products are meant for short-term use only, so follow the label directions and don’t rely on them for more than a few days.
Antimicrobial mouth rinses can also help. Chlorhexidine-based rinses have been shown to reduce pain and accelerate wound healing for oral ulcers. You can find these at most pharmacies, though some formulations require a prescription depending on the concentration. Over-the-counter antiseptic rinses containing hydrogen peroxide (diluted) serve a similar purpose by keeping the area clean and reducing bacterial load around the sore.
Foods to Avoid While It Heals
What you eat matters more than you might expect. Acidic, spicy, and rough-textured foods are the biggest offenders because they directly irritate the exposed tissue. While the sore is active, steer clear of:
- Citrus fruits and juices (oranges, lemons, grapefruit), which can prolong healing
- Tomatoes and tomato-based sauces, including ketchup and salsa
- Spicy seasonings, hot peppers, and curry
- Crunchy or sharp-edged foods like chips, pretzels, nuts, and seeds, which can scrape the sore
- Coffee and carbonated drinks, both acidic enough to cause stinging
Stick to soft, cool, or lukewarm foods. Yogurt, oatmeal, scrambled eggs, and smoothies are all easy on gum sores. If you notice that certain foods consistently trigger new outbreaks, chocolate, strawberries, and dairy are common culprits for people who are prone to canker sores.
Switch Your Toothpaste
Many popular toothpastes contain sodium lauryl sulfate (SLS), a foaming agent also found in shampoos and household cleaners. SLS is a known soft tissue irritant, and for people who get recurring canker sores, switching to an SLS-free toothpaste can make a real difference in how often outbreaks happen. Brands like Sensodyne, Biotene, and several others make SLS-free options that are easy to find at any drugstore.
While you’re healing, brush gently around the sore with a soft-bristled toothbrush. Aggressive brushing is one of the most common triggers for canker sores on the gums in the first place.
Nutrient Deficiencies That Cause Recurring Sores
If you’re getting canker sores frequently, your body may be low on specific nutrients. Deficiencies in vitamin B12, iron, zinc, and folate are all linked to recurrent oral ulcers. Vitamin B12 deficiency in particular is associated with a range of oral problems, including recurring ulcers and a burning sensation in the mouth.
You don’t necessarily need supplements. Eating more leafy greens, lean meats, eggs, legumes, and fortified cereals can close the gap for most people. But if sores keep coming back every few weeks, it’s worth asking your doctor for a blood test to check these levels. Other underlying conditions, including celiac disease, inflammatory bowel disease, and immune system disorders, can also cause chronic canker sores and are worth ruling out.
How Long Healing Takes
Minor canker sores, the kind most people get, are smaller than a pea and heal within a few weeks without scarring. Major canker sores are larger than one centimeter, extremely painful, and can take months to heal, sometimes leaving scars. There’s also a rare type called herpetiform canker sores, where tiny pinpoint sores cluster together. These typically heal within about two weeks.
If your sore hasn’t started shrinking after two weeks, is unusually large, comes with a fever, or makes it difficult to eat or drink, that’s a sign something more than a routine canker sore is going on.
Canker Sores vs. Cold Sores
A sore on your gums that’s inside your mouth is almost certainly a canker sore, not a cold sore. Cold sores are caused by the herpes simplex virus (HSV-1), are contagious, and almost always appear on or around the lips, on the outside of the mouth. Canker sores are not viral, not contagious, and only form on soft tissue inside the mouth: the gums, inner cheeks, tongue, and soft palate.
If you’re seeing a cluster of small blisters on the outer edge of your lip that tingle or burn before they appear, that’s a cold sore and requires a different treatment approach. A single round ulcer with a white center sitting at the base of your gumline is a textbook canker sore.
Common Triggers to Watch
The exact cause of canker sores is still unknown, but researchers have identified a consistent set of triggers. Emotional stress, hormonal shifts during menstruation, minor mouth injuries from dental work or cheek biting, and food sensitivities all play a role. Even the bacteria H. pylori, the same one associated with stomach ulcers, has been linked to outbreaks.
Keeping a simple log of when your canker sores appear, and what happened in the days before, can help you spot your personal pattern. For many people, the combination of switching to an SLS-free toothpaste, managing stress, and avoiding their specific food triggers is enough to dramatically reduce how often sores show up.