Most mouth ulcers heal on their own within two to three weeks, but you can significantly reduce pain and speed up recovery with the right combination of home care and over-the-counter treatments. The approach depends on how severe the ulcer is: minor sores respond well to rinses and numbing gels, while larger or recurring ulcers sometimes need prescription-strength treatment.
Salt Water Rinses
A simple salt water rinse is one of the most effective first steps. Mix about one teaspoon (5 grams) of salt into a cup (250 ml) of warm water, swish gently for 30 to 60 seconds, and spit it out. This creates roughly a 2% saline solution, which lab research has shown promotes cell migration and boosts production of collagen and fibronectin, two proteins essential for wound repair. It also helps keep the area clean. You can repeat this several times a day, especially after meals.
Over-the-Counter Numbing Gels
When the pain makes eating or talking difficult, topical gels containing benzocaine provide fast, temporary relief. Benzocaine is a local anesthetic that numbs the nerve endings directly at the ulcer site. You apply a small amount to the sore with a clean finger or cotton swab, and the effect typically lasts 15 to 30 minutes. This is especially useful right before meals.
Protective pastes that coat the ulcer and shield it from friction can also help. These barrier-type products stick to the moist tissue inside your mouth and reduce irritation from food, teeth, and tongue movement throughout the day.
Antimicrobial Mouthwashes
Chlorhexidine gluconate mouthwash can reduce the severity and pain of mouth ulcers, though it won’t prevent new ones from forming. It works by lowering the bacterial load around the sore, which helps prevent secondary infection and supports cleaner healing. You can find chlorhexidine rinses at most pharmacies without a prescription in many countries, though availability varies. Follow the product instructions carefully, as chlorhexidine can temporarily stain teeth with prolonged use.
Prescription Options for Severe Ulcers
If over-the-counter treatments aren’t enough, a doctor or dentist can prescribe topical corticosteroids. These are anti-inflammatory agents applied directly to the ulcer, and they represent the most evidence-backed approach for speeding up healing. A common option is a steroid paste that you dab onto the sore two to four times a day. It reduces inflammation while also forming a protective coating over the ulcer.
For more widespread ulceration, where multiple sores are present at once, a steroid-based mouth rinse may be prescribed instead. You swish the liquid around your mouth and spit it out. One thing to be aware of: steroid rinses can increase the risk of a secondary fungal infection (oral thrush) in the mouth, so your provider will typically monitor for that.
Foods to Avoid While Healing
What you eat matters more than you might expect. Certain foods chemically irritate the open sore and slow healing. While your ulcer is active, try to limit or avoid:
- Acidic fruits: oranges, lemons, limes, pineapples, and strawberries
- Spicy foods: hot sauces, curries, jalapenos, and spicy chips
- Hard or sharp foods: toast, raw vegetables, potato chips, and pretzels, which can physically scrape the sore
- Coffee and alcohol: both are acidic and can sting on contact
- Salted nuts: the sodium dries out the mouth lining and can inflame tissue around the ulcer
Stick to softer, cooler foods while the sore is healing. Lukewarm soups, smoothies, scrambled eggs, and bananas are all gentle options.
Preventing Recurrence
If you get mouth ulcers frequently, your toothpaste could be a factor. Many common toothpastes contain sodium lauryl sulfate (SLS), a foaming agent that can irritate the oral lining. One clinical study found four times fewer soft tissue lesions in people using SLS-free toothpaste compared to those using a formula with SLS. Switching to an SLS-free brand is a simple change worth trying if ulcers keep coming back.
Nutritional deficiencies also play a role. Deficiencies in vitamin B12, folic acid, or iron show up in 18 to 28 percent of people with recurrent mouth ulcers, compared to about 8 percent in the general population. If your ulcers are a recurring problem, a blood test can identify whether a deficiency is contributing. Correcting it through diet or supplements often reduces the frequency of outbreaks.
When a Mouth Ulcer Needs Attention
Most canker sores are flat, with red, inflamed edges, and they resolve within two to three weeks. If yours doesn’t heal in that timeframe, it’s worth getting it checked. According to MD Anderson Cancer Center, oral cancers can sometimes look like persistent sores but tend to differ in a few ways: they often have a small lump or bump underneath that you can feel, they may bleed when they didn’t before, and a white spot that turns red or a small spot that grows larger warrants evaluation. A sore that simply won’t heal is the single most important signal to pay attention to.