Most mouth ulcers heal on their own within 10 to 14 days, but you can manage the pain and create better conditions for healing in the meantime. The honest truth is that no treatment will make an ulcer disappear overnight. What you can do is reduce irritation, numb the pain, and avoid the triggers that slow recovery or cause new ulcers to form.
Rinses That Reduce Pain and Irritation
The simplest home remedy is a warm saltwater rinse. Swish it gently around the ulcer for 15 to 30 seconds, then spit. Do this a few times a day, especially after meals when food debris can irritate the sore.
Baking soda rinses work similarly. The Mayo Clinic recommends dissolving 1 teaspoon of baking soda in half a cup of warm water. This creates a mildly alkaline solution that can neutralize acids in your mouth and soothe the irritated tissue. Neither rinse will speed up the biological healing process, but both help keep the area clean and make the ulcer less painful while your body does its work.
Over-the-Counter Topical Treatments
Numbing gels containing benzocaine are widely available at pharmacies. Benzocaine is a local anesthetic that temporarily blocks pain signals from the ulcer’s surface, giving you relief for eating or drinking. Apply a small amount directly to the ulcer with a clean finger or cotton swab. The effect typically lasts 15 to 30 minutes, so timing it before meals can help.
Protective pastes and patches are another option. These form a thin barrier over the ulcer, shielding it from contact with food, teeth, and your tongue. This physical protection can make a noticeable difference in day-to-day comfort, particularly if the ulcer is in a spot that gets bumped constantly while you chew or talk.
Foods to Avoid While You Heal
Spicy foods, citrus fruits, tomatoes, and anything highly acidic will sting on contact with an open ulcer. The UK’s National Health Service specifically advises avoiding spicy foods during an active ulcer. Crunchy foods like chips or crusty bread can also physically scrape the sore and delay healing.
Stick to soft, cool, or room-temperature foods instead. Yogurt, scrambled eggs, mashed potatoes, and smoothies are all easy choices. If you’re drinking something acidic like orange juice or coffee, using a straw can help route the liquid past the ulcer.
Prescription Options for Severe Ulcers
If your ulcers are large, extremely painful, or keep coming back, a doctor or dentist can prescribe topical corticosteroid preparations. These reduce inflammation at the ulcer site, which can shorten how long the ulcer hurts and how many total days it lasts. They don’t prevent future ulcers from forming, but they make each episode more manageable.
Stronger formulations exist for stubborn cases. These are typically applied directly to the ulcer as a paste or gel, not taken as a pill. Your provider will choose the strength based on how severe and frequent your ulcers are.
Preventing Ulcers From Coming Back
If you get mouth ulcers regularly, your toothpaste may be worth examining. Many standard toothpastes contain sodium lauryl sulfate (SLS), a foaming agent that can irritate oral tissue. A double-blind trial of 90 people who regularly suffered from mouth ulcers found that switching to SLS-free toothpaste didn’t reduce the number of ulcers, but participants reported less pain and slightly faster healing. If your ulcers are particularly painful, it’s a low-risk change to try.
Nutrient deficiencies are another common culprit behind recurrent ulcers. Low levels of vitamin B12, folate, and iron have all been linked to repeated outbreaks. If you’re getting ulcers frequently and can’t identify an obvious trigger, a blood test to check these levels is a reasonable step. Correcting a deficiency, whether through diet or supplements, can reduce how often ulcers appear.
Mechanical trauma matters too. Biting your cheek, a sharp tooth edge, or poorly fitting braces or dentures can repeatedly damage the same spot and trigger ulcers. If you notice ulcers forming in the same location, a dentist can smooth a rough tooth edge or adjust an appliance to eliminate the source of irritation.
When a Mouth Ulcer Needs Medical Attention
A typical ulcer is small, round, and painful but starts improving within a week. An ulcer that persists for more than two weeks without signs of healing warrants a visit to your doctor or dentist. The Mayo Clinic flags this as a threshold because a non-healing mouth sore is one of the possible signs of oral cancer, along with white or reddish patches inside the mouth, unexplained lumps, ear pain, or difficulty swallowing.
Unusually large ulcers (bigger than a centimeter across), ulcers that spread, or ulcers accompanied by high fever also need professional evaluation. Recurrent mouth sores can occasionally signal systemic conditions. Behçet’s disease, for instance, produces painful mouth ulcers that look identical to ordinary canker sores but recur frequently and appear alongside other symptoms like genital sores, skin rashes, and eye inflammation. Celiac disease is another condition where mouth ulcers can be an early clue.
For the vast majority of people, a mouth ulcer is a temporary annoyance that resolves within two weeks. Keeping the area clean, avoiding irritants, and using a numbing gel when needed will get you through the worst of it.