Most mouth sores heal on their own within one to two weeks, but the right care can cut down on pain and speed that timeline. What works best depends on the type of sore you’re dealing with and what’s triggering it. Here’s what actually helps, from simple rinses you can make at home to changes that prevent sores from coming back.
Canker Sores vs. Cold Sores
Before treating a mouth sore, it helps to know which kind you have, because the treatments differ. Canker sores appear inside the mouth and are usually a single round white or yellow sore with a red border. Cold sores (fever blisters) show up outside the mouth, typically around the border of the lips, and look like a cluster of small, fluid-filled blisters. Canker sores are not contagious and aren’t caused by a virus. Cold sores are caused by the herpes simplex virus and require antiviral treatment rather than the remedies described below.
The rest of this article focuses primarily on canker sores and general mouth ulcers, which are by far the most common reason people search for relief.
Saltwater and Baking Soda Rinses
A simple rinse is one of the fastest, cheapest ways to reduce pain and keep the sore clean. Memorial Sloan Kettering Cancer Center recommends mixing 1 teaspoon of salt and 1 teaspoon of baking soda into 1 quart (4 cups) of water. Swish gently for 15 to 30 seconds and spit. You can also use just salt or just baking soda if that’s what you have on hand, using the same 1 teaspoon per quart ratio.
The salt helps draw fluid from swollen tissue, while the baking soda creates a mildly alkaline environment that’s less irritating than your mouth’s normal chemistry. Rinsing after meals and before bed keeps food debris away from the sore and gives you the most consistent relief.
Over-the-Counter Pain Relief
Topical gels and liquids containing numbing agents like benzocaine or lidocaine work by blocking nerves from sending pain signals. You apply them directly to the sore, and they typically numb the area within a minute or two. The relief usually lasts long enough to eat a meal comfortably, though you may need to reapply several times a day.
Protective pastes and patches offer a different approach. Rather than numbing, they form a physical barrier over the sore that shields it from food, drinks, and the friction of your teeth and tongue. Some products combine both strategies, using a numbing agent inside an adhesive patch. If your sore is in a spot that gets constantly bumped (inside the cheek, edge of the tongue), a barrier-type product often works better than a gel that washes away quickly.
Foods and Drinks to Avoid
What you eat matters more than most people expect. Acidic foods like oranges, lemons, grapefruits, tomato-based sauces, and vinegar-heavy dressings cause a sharp sting when they contact an open sore and can slow healing. Carbonated drinks irritate for the same reason. Spicy foods containing chili peppers or hot sauce create a burning sensation that can linger well after the meal is over. Even very salty or heavily processed foods draw moisture from the tissue around the sore, causing a stinging sensation that makes everything feel worse.
Stick to soft, bland, room-temperature foods while a sore is active. Yogurt, oatmeal, scrambled eggs, bananas, and cooled soups are all easy choices. Drinking through a straw can help liquids bypass a sore on the front of your mouth.
Switch to SLS-Free Toothpaste
Sodium lauryl sulfate (SLS) is a foaming agent found in most toothpastes, and it has been linked to canker sore outbreaks in multiple studies. In one clinical trial, 90 participants used two different toothpastes for eight weeks each. When they used the SLS-free version, 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 toothpaste reduces how often canker sores appear in the first place.
If you get canker sores more than a few times a year, this is one of the simplest changes you can make. Several widely available brands sell SLS-free options, and they clean your teeth just as well.
Prescription Options for Severe Sores
When over-the-counter products aren’t enough, a doctor or dentist can prescribe a steroid dental paste. These work by reducing inflammation directly at the sore site. The typical routine is to apply the paste after meals and at bedtime, which keeps the medication in contact with the sore during the periods when you’re not eating. Most people notice a significant drop in pain within a day or two, and the sore often heals faster than it would on its own.
For very large or unusually painful ulcers, a prescription-strength numbing rinse may also be an option. These rinses contain a higher concentration of anesthetic than what’s available over the counter and are swished around the entire mouth before meals.
Nutritional Deficiencies That Cause Recurring Sores
If you keep getting mouth sores despite good oral care, a nutritional gap could be the underlying cause. Research has found significant associations between recurrent canker sores and deficiencies in iron, vitamin B12, and folate. One study found B12 deficiency in 7% of patients with recurrent mouth ulcers, and case reports have documented a clear relationship between correcting B12 levels and stopping the cycle of ulcers entirely.
These deficiencies don’t always produce obvious symptoms beyond the sores themselves, so they’re easy to miss. A simple blood test can check your levels. People who follow restrictive diets, have absorption issues, or eat very little red meat and leafy greens are at higher risk. If a deficiency is confirmed, correcting it through diet or supplementation often reduces or eliminates recurrent sores over the following months.
When a Mouth Sore Needs Medical Attention
A sore that lasts longer than three weeks without healing should be evaluated by a doctor or dentist. While most mouth sores are harmless, a persistent sore can occasionally be an early sign of oral cancer. During an exam, a healthcare provider will look for lumps, areas of irritation, or white patches called leukoplakia. If anything looks concerning, the next step is a biopsy, where a small tissue sample is removed and tested in a lab.
Other reasons to get a sore checked: it’s unusually large (bigger than a pencil eraser), keeps coming back in the same spot, comes with a fever, or makes it too painful to drink fluids. Sores that spread rapidly or appear in clusters alongside other symptoms like joint pain or eye irritation can signal an underlying condition that needs treatment beyond what home care can provide.