Most mouth ulcers can’t be “cured” instantly, but you can significantly speed healing and cut the pain while they resolve on their own. Minor mouth ulcers, the most common type, typically heal within two weeks. What you do in those first few days makes a real difference in how long they stick around and how much they hurt.
Why Mouth Ulcers Happen
Mouth ulcers (also called canker sores) form when the thin tissue lining your mouth breaks down and exposes the nerve-rich layer underneath. Common triggers include biting your cheek, rough brushing, stress, hormonal changes, acidic foods like citrus or tomatoes, and even certain toothpastes. They appear as small white or yellowish craters with a red border, usually on the inner lips, cheeks, or tongue.
Recurring ulcers sometimes point to a nutritional gap. Low vitamin B12 (below 200 pg/mL), low folate (below 3 ng/mL), and iron deficiency are all linked to frequent outbreaks. If you get mouth ulcers repeatedly, a blood test checking these levels is a reasonable step.
Saltwater Rinses and Other Home Options
A warm saltwater rinse is the simplest first-line treatment. Dissolve half a teaspoon of table salt in a glass of lukewarm water and swish it gently around the ulcer for 15 to 30 seconds. Repeat this several times a day, especially after meals. The salt draws fluid from the inflamed tissue, which reduces swelling and creates a less hospitable environment for bacteria.
You can also dab a small amount of baking soda paste (baking soda mixed with a few drops of water) directly onto the sore. This neutralizes acids in the mouth that irritate the open tissue. Honey applied directly to the ulcer several times a day acts as a natural barrier and has mild antibacterial properties. Ice chips held against the sore won’t speed healing, but they numb the area and make eating more tolerable.
Over-the-Counter Treatments That Work
Numbing gels containing benzocaine are the fastest way to get pain relief. Apply a thin layer directly to the ulcer before meals or whenever the pain spikes. The effect lasts about 30 minutes, enough to eat or drink comfortably. Look for products specifically labeled for mouth sores rather than general oral pain relievers, since they tend to adhere better to wet tissue.
Protective pastes that form a barrier over the ulcer are another solid option. These coat the exposed tissue so food, drinks, and your tongue stop aggravating it. Some combine a numbing agent with a protective layer, which handles both pain and mechanical irritation at once.
Antiseptic mouthwashes containing chlorhexidine can help prevent the ulcer from picking up a secondary infection, which is what causes some sores to linger longer than they should. A meta-analysis of post-surgical oral wound healing found that chlorhexidine significantly improved healing outcomes compared to controls. For mouth ulcers specifically, it keeps the area clean while your body does the repair work. These rinses are available over the counter in many countries, though some formulations require a prescription.
Switch Your Toothpaste
This is one of the most overlooked fixes. Many popular toothpastes contain sodium lauryl sulfate (SLS), a foaming agent that strips away the protective mucous layer in your mouth. A preliminary study found that people who switched to an SLS-free toothpaste experienced roughly a 70% reduction in ulcer recurrence compared to their pre-study baseline. Even compared to using a toothpaste with standard SLS levels, the reduction was around 60%. If you get mouth ulcers more than a few times a year, switching toothpaste is one of the easiest changes you can make. Several major brands now sell SLS-free options, usually marketed for sensitive mouths.
Prescription Options for Stubborn Ulcers
If over-the-counter treatments aren’t enough, your doctor or dentist can prescribe a steroid paste. These work by suppressing the inflammatory response at the ulcer site, which reduces pain and allows tissue to rebuild faster. The paste is typically applied at bedtime so it stays in contact with the sore overnight, with additional applications after meals if the ulcer is severe.
For people with frequent, painful outbreaks, a dentist may offer laser treatment. A low-level laser applied directly to the sore provides near-immediate pain relief for many patients, and treated ulcers tend to heal faster than untreated ones. The procedure takes only a few minutes and doesn’t require anesthesia.
What to Avoid While Healing
Certain foods and habits slow healing noticeably. Acidic foods (oranges, tomatoes, vinegar-based dressings) burn the exposed tissue and can widen the ulcer. Spicy foods do the same. Crunchy or sharp-edged foods like chips and crackers can physically scrape the sore and restart the healing clock. Alcohol-based mouthwashes, despite feeling like they’re “cleaning” the ulcer, actually irritate the tissue and can delay recovery.
Try to avoid touching the ulcer with your tongue. This is surprisingly hard since your tongue naturally gravitates toward anything unusual in your mouth, but repeated contact creates friction that slows the repair process.
The Three Types and Their Timelines
Minor mouth ulcers are by far the most common. They’re smaller than a pea, and they heal within a few weeks without leaving a scar. This is what most people are dealing with when they search for a cure.
Major mouth ulcers are larger than one centimeter, extremely painful, and can take months to heal. They often leave scars. If you have a deep, unusually large sore that isn’t improving after two or three weeks of home treatment, this may be what you’re dealing with, and it’s worth getting a professional opinion.
Herpetiform ulcers are rare and show up as clusters of tiny pinpoint sores rather than a single crater. Despite the name, they aren’t caused by the herpes virus. They typically heal within about two weeks without scarring.
When a Mouth Ulcer Needs Professional Attention
A mouth ulcer that hasn’t healed after three weeks needs to be evaluated. UK clinical guidelines specifically recommend referral on a suspected cancer pathway for unexplained oral ulcers lasting longer than three weeks. This doesn’t mean your sore is cancer, but persistent ulcers are one of the ways oral squamous cell carcinoma first appears, and catching it early changes outcomes dramatically.
The warning signs that distinguish a potentially serious ulcer from a regular canker sore: it’s painless (or only mildly uncomfortable rather than the sharp sting of a typical ulcer), it has raised, rolled edges that feel firm or hard when you press on them, it bleeds easily with minor contact, or it’s accompanied by a persistent lump in your neck. Unexplained numbness in your lower lip or tongue is another red flag. Risk factors include tobacco use, heavy alcohol consumption, and a family history of oral cancer.
You should also seek evaluation if you get ulcers so frequently that new ones appear before old ones finish healing, or if topical treatments aren’t making any difference. Recurrent ulcers of unknown cause sometimes signal an underlying condition that blood work or further testing can identify.