Most mouth ulcers heal on their own within one to two weeks, but if you’re getting them repeatedly, several practical changes can cut both their frequency and how long they last. The strategies that work best target the most common triggers: irritating ingredients in your toothpaste, nutritional gaps, and specific foods that damage the mouth’s protective lining.
Switch to an SLS-Free Toothpaste
One of the simplest and most effective changes you can make is switching your toothpaste. Most toothpastes contain sodium lauryl sulfate (SLS), a foaming agent that irritates the mouth’s mucous lining and can trigger ulcer outbreaks. A meta-analysis of clinical trials found that people who switched to SLS-free toothpaste developed roughly one fewer ulcer per outbreak, experienced about two fewer days of healing time per ulcer, had fewer episodes overall, and reported significantly less pain.
Check the ingredients list on your current tube. If sodium lauryl sulfate is listed, look for brands specifically marketed as SLS-free. This single swap is one of the most well-supported prevention strategies available.
Identify and Avoid Trigger Foods
Certain foods lower the pH inside your mouth, disrupting the protective protein layer that shields your oral tissue. The biggest culprits are citrus fruits, fizzy drinks, and alcohol. Less obvious triggers include strawberries and tomatoes, which many people don’t think of as acidic but can be enough to set off an ulcer.
Spicy and salty foods also irritate the delicate mucosal lining directly. If you notice a pattern between certain meals and ulcer outbreaks, keeping a brief food diary for a few weeks can help you pinpoint your personal triggers. You don’t necessarily need to eliminate these foods permanently, but cutting back during periods when you’re prone to outbreaks can make a noticeable difference.
If you already have an active ulcer, texture matters too. Hard, crunchy, or sharp-edged foods like crusty bread, chips, or raw vegetables can physically aggravate the sore and slow healing.
Address Nutritional Deficiencies
Recurrent mouth ulcers are sometimes a sign that your body is low on certain nutrients, particularly vitamin B12, iron, and folate. A clinical trial registered through ClinicalTrials.gov tested daily sublingual B12 tablets (1,000 mcg taken before bed) over six months in people with recurrent ulcers. The study design reflects a well-established clinical suspicion: even people whose blood levels of B12 appear normal sometimes see improvement with supplementation.
If your ulcers keep coming back despite other changes, it’s worth having your B12, iron, and folate levels checked through a simple blood test. Correcting a deficiency, if one exists, can dramatically reduce how often ulcers appear. Good dietary sources of these nutrients include leafy greens, eggs, meat, fortified cereals, and legumes.
Use a Salt Water Rinse
A warm salt water rinse is the most accessible home treatment for an active ulcer. Mix one teaspoon of salt into one cup of warm (not hot) water. Swish gently around your mouth for five to ten seconds, then spit it out. You can do this several times a day. Salt water creates an environment that’s less hospitable to bacteria, helping the ulcer stay clean while it heals. It will sting briefly, but the discomfort fades quickly.
Over-the-Counter Pain Relief
When an ulcer is actively painful, topical gels containing 20% benzocaine can numb the area on contact. These are available without a prescription and are applied directly to the dried surface of the ulcer. The numbing effect is temporary but can make eating and drinking much more comfortable. Some formulations also include menthol and zinc chloride, which provide a mild cooling sensation and additional antiseptic action.
Protective pastes that form a barrier over the ulcer are another option. These stick to the sore and shield it from further irritation by food and drink, giving the tissue underneath a better chance to heal without being repeatedly disturbed.
Prescription Options for Severe Cases
If you get large, frequent, or especially painful ulcers that don’t respond to the strategies above, prescription-strength treatments exist. The most common are steroid-based: a paste applied directly to the ulcer several times a day, or a medicated rinse you swish and spit twice daily. These reduce inflammation and speed healing. One thing to be aware of is that prolonged use of steroid rinses can sometimes lead to a secondary fungal infection in the mouth, so they’re typically used for defined periods rather than indefinitely.
Reduce Physical Irritation
Mouth ulcers often start at a site of physical trauma. Biting the inside of your cheek, brushing too aggressively, or having a rough edge on a tooth or dental appliance can all create the initial wound that develops into an ulcer. Using a soft-bristled toothbrush helps. If you notice ulcers repeatedly forming in the same spot, check whether a sharp tooth edge, a poorly fitting denture, or orthodontic hardware is rubbing against that area. A dentist can smooth rough surfaces or adjust appliances to eliminate the source of friction.
When an Ulcer Needs Attention
The two-week rule is the key benchmark. A typical mouth ulcer is small and round with a white or yellowish center and a red border. It hurts, but it heals within one to two weeks without treatment. If an ulcer hasn’t healed after two weeks, is unusually large, or comes with a fever or swollen lymph nodes, it needs professional evaluation.
It’s worth knowing that oral cancer lesions can sometimes look similar to ordinary ulcers, appearing as persistent sores, red or white patches, or lumps anywhere in the mouth. One important distinction: while regular ulcers are reliably painful, mouth cancer is not always painful. A sore that doesn’t hurt but also doesn’t heal is actually more concerning than one that stings. Any non-healing lesion lasting beyond two weeks warrants a visit to your dentist or doctor.