Most mouth ulcers (canker sores) heal on their own within 10 to 14 days, but you can speed up pain relief and support healing with a few straightforward strategies. The key is reducing irritation, managing pain, and creating the right conditions for the tissue to repair itself.
Salt Water and Baking Soda Rinses
The simplest and most accessible treatment is a homemade mouth rinse. 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 30 seconds and spit. You can also use just salt or just baking soda if that’s what you have on hand, keeping the same ratio of 1 teaspoon per quart. These rinses help keep the ulcer clean and create an environment that discourages bacterial growth. Rinsing several times a day, especially after meals, is a good baseline habit while your ulcer heals.
Over-the-Counter Pain Relief
Topical numbing agents containing benzocaine are widely available as gels, sprays, and ointments. You apply them directly to the ulcer up to four times a day. They temporarily block pain signals at the surface, giving you relief while eating or talking. These products are safe for adults and children over two years old.
Protective pastes and patches that coat the ulcer can also help. They form a barrier between the sore and your food, tongue, and teeth, which reduces both pain and mechanical irritation that slows healing. Look for products labeled specifically for mouth sores or canker sores at any pharmacy.
Prescription Treatments
If your ulcers are large, unusually painful, or keep coming back, a doctor or dentist can prescribe a topical steroid paste. Triamcinolone 0.1% in an oral adhesive base is one of the most commonly used options. You dry the ulcer gently, then apply a thin layer two to four times daily until it heals. The steroid reduces inflammation and can shorten healing time, particularly for more severe ulcers.
For stubborn or frequent outbreaks, your provider may also consider chemical cautery. Silver nitrate, applied once directly to the ulcer, has been shown to reduce pain severity in about 70% of patients within one day, compared to just 11% with a placebo. It won’t make the ulcer heal faster (both groups healed in about five and a half days in one clinical trial), but the pain relief can be significant.
Avoid Foods That Irritate the Sore
What you eat matters more than you might expect. Acidic foods cause a burning sensation on open ulcers and can delay healing. While your ulcer is active, try to limit or avoid:
- Citrus fruits and fruit juice
- Tomatoes
- Berries and pineapple
- Vinegar
- Coffee and alcohol
Spicy foods and anything with sharp edges (chips, crusty bread, raw vegetables) can also reopen or further irritate the wound. Softer, cooler foods are easier on your mouth during the healing window. Think yogurt, smoothies, scrambled eggs, and oatmeal.
Check Your Toothpaste
Sodium lauryl sulfate (SLS) is a foaming agent found in many toothpastes, and it’s a known trigger for canker sores in some people. If you get ulcers regularly, switching to an SLS-free toothpaste is one of the simplest changes you can make. Several brands market SLS-free options specifically for sensitive mouths. Give it a few months to see if your outbreak frequency drops.
Nutritional Gaps That Cause Recurring Ulcers
Occasional mouth ulcers are common and usually harmless. But if you’re getting them repeatedly, a nutritional deficiency could be the underlying cause. Research on patients with recurrent canker sores has found that about 20% are anemic, roughly 20% have low iron levels, and around 5 to 7% are deficient in vitamin B12. Folate deficiency shows up in a smaller percentage as well.
These deficiencies impair your body’s ability to maintain and repair the soft tissue lining your mouth. If you deal with frequent ulcers, it’s worth asking your doctor to check your blood levels for iron, B12, and folate. Correcting a deficiency often reduces or eliminates the recurrences entirely.
Know the Different Types
Not all mouth ulcers behave the same way. Minor canker sores, the most common type, are small (under 1 cm), appear on the inner cheeks, lips, or tongue, and heal within 10 to 14 days without scarring. These are the ones that respond well to the home and OTC strategies above.
Major canker sores are larger, deeper, and significantly more painful. They can take up to six weeks to heal and often leave scars. These typically need prescription treatment rather than just home care.
Herpetiform ulcers are a third, less common type. They appear as clusters of tiny sores that can merge into larger irregular ulcers. Despite the name, they aren’t caused by the herpes virus.
When a Mouth Ulcer Needs Medical Attention
A single ulcer that heals within two weeks is almost never cause for concern. But certain patterns warrant a closer look. Any mouth ulcer that hasn’t healed after three weeks should be evaluated by a doctor or dentist. Persistent, non-healing ulcers are one of the recognized red flags for oral cancer, along with unexplained lumps, difficulty opening your mouth, or numbness in the lip or tongue.
You should also seek evaluation if your ulcers are unusually large (bigger than a dime), come with a high fever, make it difficult to drink fluids, or keep recurring without an obvious trigger. A biopsy or referral to a specialist can rule out more serious conditions and get you a targeted treatment plan.