Most canker sores heal on their own within a few weeks, but the right combination of home care and over-the-counter products can cut down pain and speed that timeline. These small, round ulcers inside the mouth are not the same as cold sores, and while there’s no instant cure, several approaches work well to manage them.
Salt Water and Baking Soda Rinses
The simplest and most effective home remedy is a warm rinse made with salt and baking soda. This combination reduces acid levels in your mouth, keeps the sore clean, and creates an environment that promotes healing. Mix 1 teaspoon of table salt and 1 teaspoon of baking soda into 4 cups of warm water. Swish it around your mouth for 15 to 30 seconds, then spit it out. Repeat every 4 to 6 hours throughout the day.
This rinse won’t sting the way pure salt water sometimes can, and it helps make eating, drinking, and talking more comfortable almost immediately. You can store the solution in a sealed container at room temperature and use it throughout the day.
Over-the-Counter Pain Relief
Topical gels and ointments containing benzocaine are the most widely available OTC option for numbing canker sore pain. Apply the gel directly to the sore up to four times a day. The numbing effect kicks in quickly and makes meals far more manageable. Don’t use benzocaine products for more than two days without checking with a doctor, and avoid them entirely for children under two years old.
Other OTC products come as pastes, creams, or liquids that coat the sore and form a protective barrier. These work best when applied as soon as a sore appears. Look for products specifically marketed for mouth ulcers at any pharmacy.
Foods That Make Things Worse
What you eat while a canker sore is active matters more than most people realize. Acidic foods are the biggest offenders: citrus fruits and juices (oranges, grapefruits, lemons, limes, pineapple), tomatoes and tomato-based sauces, strawberries, coffee, and soda all irritate the exposed tissue and can delay healing. Spicy foods containing hot peppers do the same.
Physically rough foods also cause problems. Chips, pretzels, nuts, and crusty bread can scrape against the sore and reopen it. During an active outbreak, stick to softer, cooler, bland foods. Think yogurt, oatmeal, mashed potatoes, and smoothies.
When Sores Need Prescription Treatment
For canker sores that are especially large, painful, or frequent, a doctor or dentist can prescribe stronger options. Steroid mouth rinses reduce inflammation and pain more aggressively than anything available over the counter. Prescription-strength topical gels can also be applied directly to stubborn sores. In severe cases that don’t respond to topical treatment, oral medications may be used, though steroid pills are typically a last resort because of their side effects.
Dental offices increasingly offer laser treatment for canker sores as well. A session takes under a minute per sore, provides near-immediate pain relief, and can accelerate healing. If you get frequent or severe outbreaks, ask your dentist whether laser treatment is available.
How Long Healing Takes
Minor canker sores, the most common type, are smaller than a pea (under one centimeter across). These typically heal within two to three weeks without leaving a scar. Major canker sores are larger than one centimeter, cause significant pain, and can take months to fully heal. They often leave scars.
You should contact a healthcare provider if a canker sore lasts longer than two weeks, is larger than a pea, comes with fever or flu-like symptoms, keeps coming back two or three times a year, or interferes with your ability to eat and drink normally.
Preventing Future Outbreaks
Canker sores don’t have a single known cause, but several triggers are well established: mouth injuries (biting your cheek, aggressive brushing), stress, and certain nutritional gaps.
One surprisingly common trigger is toothpaste containing sodium lauryl sulfate (SLS), a foaming agent found in many major brands. SLS irritates the soft tissue lining your mouth and is linked to recurring canker sores. Switching to an SLS-free toothpaste is one of the easiest prevention steps you can take. Check the ingredients list on your current tube, as many popular brands include it.
Nutritional deficiencies in vitamin B12, folic acid, and iron have been found in 18 to 28 percent of people with recurring canker sores, compared to about 8 percent of healthy controls. If you get canker sores frequently, it’s worth having your levels checked. People with celiac disease or gluten sensitivity also experience more frequent outbreaks, possibly because intestinal inflammation impairs nutrient absorption.
Canker Sores vs. Cold Sores
These are completely different conditions that require different treatment. Canker sores appear inside your mouth, on the inner cheeks, lips, or tongue. They look like single round white or yellow sores with a red border. They are not contagious and are not caused by a virus.
Cold sores (fever blisters) appear outside the mouth, typically around the border of the lips. They show up as clusters of small fluid-filled blisters and are caused by the herpes simplex virus. If your sore is on the outside of your lips and looks like a blister, the treatments described in this article won’t help, as you’d need antiviral medication instead.