Most mouth ulcers (canker sores) heal on their own within 7 to 14 days, but the right combination of rinses, topical treatments, and dietary adjustments can cut pain significantly and speed that timeline. The key is reducing irritation, keeping the area clean, and managing pain so you can eat and drink normally while the ulcer runs its course.
What’s Happening Inside Your Mouth
A typical mouth ulcer goes through three stages. First comes a tingling or burning sensation that lasts one to three days before the sore is visible. Then the ulcer fully forms, usually by day three, and stays open and painful for another three to six days. After that, the tissue gradually closes and heals. Mild ulcers leave no scarring. Knowing where you are in this cycle helps set expectations: if the sore just appeared, you likely have about a week of active healing ahead, and everything you do now is about shortening that window and staying comfortable.
Salt Water and Baking Soda Rinses
A saltwater rinse is the simplest and most accessible first step. Salt reduces inflammation and lowers the acidity around the ulcer, which both relieves pain and creates a better environment for healing. Mix one teaspoon of salt into one cup of warm water, swish it around your mouth for about 30 seconds, and spit it out. You can do this several times a day, especially after meals. It will sting briefly on contact, but the discomfort fades quickly.
Never apply dry salt directly to the sore. It causes intense pain without any healing benefit. You can swap in baking soda instead of salt (same ratio, one teaspoon per cup) for a similar acid-neutralizing effect, or alternate between the two.
Honey as a Healing Aid
Applying honey directly to a mouth ulcer several times a day can reduce pain, inflammation, and ulcer size. Honey contains natural compounds that kill bacteria and promote tissue repair. The research showing the strongest results has used manuka honey specifically, which has higher concentrations of these active compounds than regular table honey. Dab a small amount onto the sore with a clean finger or cotton swab after eating. It won’t sting the way salt water does, making it a good option if you find rinses too uncomfortable.
Hydrogen Peroxide Rinse
An antiseptic hydrogen peroxide rinse helps keep the ulcer clean and prevents secondary infection from slowing healing. Look for a mouth sore rinse with 1.4% hydrogen peroxide concentration, which is formulated to be safe for oral tissue. Swish one capful (about 10 ml) around the affected area for at least one minute, then spit it out. You can use it up to four times daily, after meals and before bed. Don’t continue using it for more than seven days in a row.
Do not use the 3% hydrogen peroxide from your medicine cabinet undiluted. It’s too strong for oral tissue and can damage the healing surface of the ulcer.
Over-the-Counter Numbing Gels
When pain makes eating or talking difficult, a topical numbing gel provides fast, targeted relief. Products containing 20% benzocaine numb the nerve endings at the ulcer surface almost immediately on contact. Some formulas add menthol for a soothing effect and an astringent ingredient that forms a mild protective barrier over the sore. Apply the gel directly to the ulcer with a clean fingertip or cotton swab. The numbing effect is temporary, so you may need to reapply before meals or whenever pain flares.
These gels work best as a pain management tool rather than a healing accelerator. They make the ulcer livable while your body does the actual repair work underneath.
Prescription Options for Severe Ulcers
If your ulcer is large, extremely painful, or keeps coming back, a doctor or dentist can prescribe a topical corticosteroid gel or cream. These medications suppress the inflammatory response directly at the sore, which reduces swelling and pain more aggressively than over-the-counter options. They’re applied directly to the ulcer, usually several times a day. Prescription treatment is most useful for people who get frequent or unusually large ulcers that don’t respond well to home care.
What to Avoid While Healing
Certain foods and habits can re-injure the ulcer and reset the healing clock. Acidic foods like citrus fruits, tomatoes, and vinegar-based dressings increase pain and irritation at the ulcer site. Spicy foods, crunchy chips, and hard bread can physically scrape the sore. Alcohol-based mouthwashes burn on contact and can dry out the tissue around the ulcer, slowing repair.
Stick to soft, bland, cool foods while the ulcer is active. Yogurt, scrambled eggs, oatmeal, and smoothies are all easy choices. Drinking through a straw can help liquids bypass a sore on the front of your mouth or lips.
Preventing Ulcers From Coming Back
If you get mouth ulcers repeatedly, the cause is often a combination of minor triggers rather than one single factor. Nutritional deficiencies play a documented role. Low levels of vitamin B12, zinc, and iron are all linked to recurrent mouth ulcers. A daily B12 supplement (doses used in studies range from 3 to 1,000 mcg) and zinc supplementation can help if your levels are low. If you take zinc long-term, pairing it with 1 to 2 mg of copper daily prevents a copper deficiency that high-dose zinc can cause.
Some people find that switching toothpaste makes a difference. Sodium lauryl sulfate (SLS), the foaming agent in most toothpastes, is a known irritant for some individuals. A 2019 review found there wasn’t enough data to definitively prove that SLS-free toothpaste reduces ulcer frequency across the general population, but individual responses vary. If you notice ulcers tend to appear after brushing, trying an SLS-free brand for a few months is a low-risk experiment.
Other common triggers include biting the inside of your cheek, poorly fitting dental work, stress, hormonal changes, and sleep deprivation. Keeping a simple log of when ulcers appear can help you identify your personal pattern.
When a Mouth Ulcer Needs Medical Attention
The three-week mark is the critical threshold. If a mouth ulcer hasn’t healed after three weeks, it needs to be evaluated by a doctor or dentist. Persistent ulcers can occasionally signal something more serious, including oral cancer, autoimmune conditions, or chronic infections that require different treatment. Other signs worth getting checked include ulcers that are unusually large (bigger than a centimeter across), sores that keep appearing in the same spot, ulcers accompanied by fever, or clusters of sores that spread rapidly.