Most mouth ulcers (canker sores) heal on their own within one to two weeks, but the right treatment can cut pain and speed that timeline. No single remedy works dramatically better than all others, and a network meta-analysis of topical treatments found no statistically significant winner when different medications were compared head-to-head for pain reduction. That sounds discouraging until you realize the practical takeaway: several approaches genuinely help, and the best strategy usually combines a few of them rather than banking on one miracle product.
Barrier Gels and Protective Coatings
The simplest thing you can do for a mouth ulcer is shield it from further irritation. Barrier-forming products coat the raw surface so food, saliva, and your teeth stop aggravating it every few seconds. Hyaluronic acid gels and rinses are among the better-studied options here. A retrospective study of patients with minor recurrent ulcers found that both a hyaluronic acid mouth rinse and a topical gel formulation were effective, with the gel showing a trend toward earlier healing onset.1PubMed Central. Treatment of recurrent aphthous stomatitis (RAS; aphthae; canker sores) with a barrier forming mouth rinse or topical gel formulation containing hyaluronic acid: a retrospective clinical study Hyaluronic acid works partly because it is a natural component of mucosal tissue and stays in contact with the ulcer for a relatively long time, reducing pain and potentially lowering recurrence.2Journal of Indian Academy of Oral Medicine and Radiology. Assessment of Clinical Efficacy of Microbiome and Topical Hyaluronic Acid Gel Combination Therapy in Minor Aphthous Ulcer Management – A comparative study
Over-the-counter adhesive patches and pastes containing benzocaine or other mild anesthetics work on the same principle: cover the sore, reduce contact with irritants, and deliver a small dose of numbing agent. The coating itself may matter as much as the active ingredient, since keeping the wound undisturbed is half the battle.
Topical Pain Relief and Its Limits
Numbing agents like lidocaine gels and benzocaine pastes are the go-to for immediate pain relief. They can make eating and talking tolerable for a short window. But the evidence for dramatic benefit is thinner than you might expect. A randomized trial comparing 2% viscous lidocaine to a flavored gel placebo in children with painful mouth ulcers found no meaningful difference in oral intake between the two groups one hour after application.3Annals of Emergency Medicine. A Double-Blind, Randomized, Placebo-Controlled Trial of Topical 2% Viscous Lidocaine in Improving Oral Intake in Children With Painful Infectious Mouth Conditions That does not mean numbing gels are useless for adults applying them directly to a canker sore, but it does suggest the placebo effect of any soothing gel is substantial.
A broader network meta-analysis comparing various topical treatments for recurrent aphthous ulcers came to a similarly sobering conclusion: no statistically significant differences in pain reduction emerged when different topical medications were compared to each other or even to placebo at various time points.4PubMed. Topical medications for the treatment of recurrent aphthous stomatitis: A network meta-analysis The clinical reality is that most topical treatments provide modest, short-lived relief. Prescription-strength options like topical corticosteroid pastes (triamcinolone acetonide, for instance) are still worth asking your dentist about if ulcers are large or frequent, since they target the underlying inflammation rather than just numbing the surface. But anyone expecting a topical treatment to eliminate pain overnight should temper that expectation.
Antiseptic and Medicated Rinses
Chlorhexidine gluconate mouthwash is one of the most commonly recommended antiseptic rinses for mouth ulcers. It does not speed healing in the way an antibiotic treats an infection, but it keeps the bacterial load down around the ulcer, which can prevent secondary infection and reduce discomfort. In one clinical case study, pediatric oral ulcers treated with 2% chlorhexidine gluconate gauze twice daily healed within seven days.5Journal of Holistic Nursing Science. A case study of using chlorhexidine gluconate for mouth ulcer care That is roughly in line with typical healing time for minor ulcers anyway, so the takeaway is that chlorhexidine rinses support normal healing rather than producing miraculous results. The main downside: chlorhexidine tastes terrible and can temporarily stain teeth with prolonged use.
A simpler option is rinsing with warm salt water. Dissolving about half a teaspoon of salt in a glass of warm water and swishing gently several times a day is one of the oldest home remedies for oral sores. There is limited high-quality clinical evidence specifically for salt water and canker sores, but sodium bicarbonate rinses (baking soda dissolved in water) have been shown to alter oral pH and cleanse taste bud receptors, and a similar mechanism likely helps with salt water.6PubMed. Will mouth wash solutions of water, salt, sodiumbicarbonate or citric acid improve upper gastrointestinal symptoms in chronic kidney disease These rinses can sting on contact, but they are cheap, widely available, and unlikely to cause harm.
Honey and Licorice
Honey has genuine wound-healing properties, and the evidence extends to mouth ulcers. An animal study comparing different honey delivery systems found that honey applied as a gel was more effective than a mucoadhesive form in shortening wound healing duration, with statistically significant differences visible by the third and seventh days of treatment.7PubMed Central. Effect of two different delivery systems of honey on the healing of oral ulcer in an animal model If you want to try this at home, dab a small amount of raw, unprocessed honey directly onto the ulcer a few times a day. It forms a natural protective layer and has antibacterial properties. The downside is that it washes away quickly, so reapplication is necessary.
Licorice extract is another natural remedy with a more substantial evidence base than many people assume. A systematic review of clinical trials found that topical licorice had significant effects on pain reduction, ulcer size, and healing time.8PubMed Central. Topical Licorice for Aphthous: A Systematic Review of Clinical Trials The active compound, glycyrrhizin, has dose-dependent anti-inflammatory and antioxidant effects and also appears to boost levels of epidermal growth factor, which helps maintain oral tissue integrity. Licorice-based oral patches and gels are commercially available. Importantly, topical application to the mouth is very different from eating large amounts of licorice candy, which can raise blood pressure. The topical route delivers a small, localized dose.
Switch Your Toothpaste
This is one of the most underrated interventions for people who get frequent canker sores. Sodium lauryl sulfate (SLS) is the foaming agent in most commercial toothpastes, and it can irritate oral mucosa. A systematic review pooling data from multiple trials found that switching to an SLS-free toothpaste significantly reduced the number of ulcers, duration of each ulcer episode, frequency of recurrences, and pain levels.9PubMed. Effect of sodium lauryl sulfate on recurrent aphthous stomatitis: A systematic review If you get mouth ulcers more than a few times a year, checking the ingredients list on your toothpaste is one of the easiest changes you can make. Several major brands sell SLS-free versions, and specialty oral-care lines often omit it by default.
Vitamin B12 and Folate
Nutritional deficiencies do not cause all mouth ulcers, but for a subset of people who get them repeatedly, the culprit may be low intake of vitamin B12 or folate. A study comparing the diets of people with recurrent aphthous ulcers to general population data found that ulcer sufferers consumed significantly less B12 and folate, even though their intake of nearly every other nutrient tested was actually higher than average.10PubMed Central. Reduced dietary intake of vitamin B12 and folate in patients with recurrent aphthous stomatitis That specificity is striking and suggests the link is real rather than a byproduct of generally poor nutrition.
Vitamin B12 deficiency can also produce its own oral symptoms: burning sensations of the tongue and buccal mucosa, diffuse redness, and mucosal atrophy, with oral changes sometimes appearing before any blood-related symptoms are noticeable.11PubMed Central. Oral manifestations of vitamin B12 deficiency associated with pernicious anemia: A case report A separate randomized, double-blind trial tested sublingual B12 as a pain treatment for existing aphthous ulcers and found that pain scores in the B12 group were significantly lower than placebo after just two days of treatment.12PubMed. The Effectiveness of Vitamin B12 for Relieving Pain in Aphthous Ulcers: A Randomized, Double-blind, Placebo-controlled Trial That suggests B12 may help with active ulcers even in people who are not clearly deficient, though the strongest case for supplementation is in people with documented low levels.
If you get recurrent mouth ulcers and eat relatively little meat, dairy, or leafy greens, it is worth asking your doctor to check B12 and folate levels. Correcting a genuine deficiency can reduce how often ulcers come back.
Low-Level Laser Therapy
This is probably the treatment most people have not heard of, and the evidence for it is surprisingly strong. Low-level laser therapy (LLLT), sometimes called photobiomodulation, involves a dentist or specialist applying a low-power laser directly to the ulcer for a brief session. A systematic review and meta-analysis confirmed that LLLT reduces both pain scores and healing time in recurrent aphthous ulcers.13PubMed Central. Effectiveness of low-level laser therapy in reducing pain score and healing time of recurrent aphthous stomatitis: a systematic review and meta-analysis
The numbers from individual trials are notable. In a sham-controlled, split-mouth study, ulcers in the laser-treated group resolved in about three days on average, compared to roughly nine days in the sham-control group. Twenty-eight out of thirty patients experienced complete pain relief immediately after the laser application.14PubMed Central. Efficacy of Low-Level Laser Therapy in Treatment of Recurrent Aphthous Ulcers – A Sham Controlled, Split Mouth Follow Up Study That is a meaningful difference, and it is hard to attribute entirely to placebo given the split-mouth design (each patient served as their own control, with one ulcer getting real treatment and the other a sham).
The catch is access. LLLT requires a visit to a provider who has the equipment, which typically means a dental office or oral medicine clinic. For people who get severe or frequent ulcers, the inconvenience may be worth it. For a once-a-year canker sore, it is probably overkill.
Sleep, Stress, and Other Triggers
Treatment is one thing; preventing the next ulcer is another. Recurrent aphthous ulcers have a strong immune-mediated component, with research pointing to genetically influenced disturbances in both innate and acquired immunity.15PubMed Central. Etiopathogenesis of recurrent aphthous stomatitis and the role of immunologic aspects: literature review That means anything that disrupts immune regulation can trigger a flare. Stress is the classic example, but sleep quality is an underappreciated factor.
An animal study showed that sleep deprivation worsened existing oral ulcers and delayed healing, likely through elevated inflammatory markers and disrupted stress hormones.16PubMed. Sleep deprivation worsened oral ulcers and delayed healing process in an experimental rat model Human data supports the connection too. A cohort study of adolescents found that those with the worst insomnia scores had about a 29% higher rate of recurrent aphthous ulcers, while those with hypersomnia symptoms had a 42% higher rate.17PubMed. Sleep quality and risk of recurrent aphthous ulcers: A Spanish cohort study The association held for various sleep-related problems, suggesting it is sleep quality broadly, not just one specific sleep disorder, that matters.
Food sensitivities are another trigger worth investigating if your ulcers keep coming back. One study of forty patients with recurrent ulcers found that twenty showed clinically relevant positive reactions on patch testing, and eighteen of those improved after professional advice on allergen avoidance.18PubMed. Recurrent aphthous ulceration and food sensitivity Diagnostic elimination diets, where you systematically remove and reintroduce suspect foods, are frequently used to identify triggers.19PubMed. Recurrent aphthous stomatitis caused by food allergy Common culprits include citrus, tomatoes, chocolate, coffee, nuts, and certain spices, though the specific trigger varies from person to person. If you notice a pattern, that is worth pursuing with your doctor rather than dismissing as coincidence.
When Mouth Ulcers Signal Something Else
Most canker sores are just canker sores. But recurrent or unusually persistent oral ulcers can sometimes be the first visible sign of an underlying condition, particularly gastrointestinal diseases. Inflammatory bowel diseases like Crohn’s disease and ulcerative colitis frequently produce oral manifestations, and those mouth symptoms sometimes appear before any gut symptoms do.20PubMed Central. Oral manifestation in inflammatory bowel disease: a review Celiac disease, Behçet’s disease, and other systemic conditions can also present with oral ulcers that look indistinguishable from ordinary canker sores.21PubMed Central. Oral manifestations of gastrointestinal disorders
Red flags that warrant a visit to a healthcare provider include:
- Duration: An ulcer that has not healed after three weeks.
- Size: Unusually large ulcers, particularly those over a centimeter across.
- Frequency: Near-constant ulcers, with new ones forming before old ones resolve.
- Other symptoms: Unexplained weight loss, persistent fatigue, joint pain, genital ulcers, or chronic digestive issues alongside the mouth ulcers.
- Location: Ulcers on unusual sites such as the hard palate or gums, which are less typical of simple canker sores.
A non-healing oral ulcer in an older adult, particularly someone who smokes or drinks heavily, should be evaluated promptly to rule out oral cancer. The overwhelming majority of canker sores are benign, but the cost of getting a stubborn one looked at is low compared to the cost of missing something serious.
Putting Together a Practical Routine
Given that no single treatment is head and shoulders above the rest, the most effective approach for an active ulcer combines a few strategies at once. A reasonable routine for a painful canker sore looks something like this: rinse gently with warm salt water or a baking soda solution two to three times a day, apply a barrier gel or hyaluronic acid product to protect the ulcer surface, and dab honey or a licorice-based gel onto the sore between meals. Avoid acidic, spicy, and crunchy foods that scrape the area. If the pain is interfering with eating, a topical anesthetic gel before meals can help, even if the benefit is partly from the coating rather than the drug itself.
For people who get ulcers repeatedly, the longer game matters more. Switching to SLS-free toothpaste, getting B12 and folate levels checked, identifying and avoiding food triggers, and improving sleep habits can all reduce the frequency of outbreaks over time. If ulcers are severe enough to affect your quality of life on a regular basis, ask your dentist or doctor about low-level laser therapy or prescription corticosteroid preparations. The evidence supports escalating treatment based on how much the problem disrupts your daily life, rather than reaching for the strongest option from the start.