Most canker sores heal on their own within one to two weeks without any treatment at all. But that timeline feels a lot longer when you have a painful crater on the inside of your lip that flares every time you eat, drink, or talk. The good news is that a range of options, from kitchen-shelf remedies to prescription medications to in-office procedures, can meaningfully cut pain and speed healing. Which approach makes sense depends on how severe the sore is, how often you get them, and how quickly you need relief.
Why Canker Sores Happen in the First Place
Understanding what kicks off a canker sore helps explain why so many different treatments exist. Canker sores (the medical name is recurrent aphthous stomatitis, or RAS) are shallow ulcers on the soft tissue inside your mouth. They are not caused by a virus, which is the key difference between them and cold sores, which appear on or around the lips and are triggered by herpes simplex. Canker sores form inside the mouth only, on the cheeks, gums, tongue, or soft palate.
The exact cause is still not fully pinned down, but research points to a combination of genetic predisposition, immune-system quirks, local trauma like biting your cheek, stress, hormonal shifts, and certain nutritional gaps.1PubMed Central. Management of oral aphthous ulcer: A review Immune disturbances seem to play a central role: the body’s inflammatory response essentially overshoots, breaking down a patch of oral tissue that should have healed from a minor irritation.2SpringerLink. Etiopathogenesis of recurrent aphthous stomatitis and the role of immunologic aspects: literature review Research also links shifts in the oral microbiome to the onset of mouth ulcers, suggesting that disruptions to the normal bacterial balance in the mouth can weaken the mucosal lining and set the stage for a sore to develop.3PubMed Central. Oral microbiota dysbiosis accelerates the development and onset of mucositis and oral ulcers
Food sensitivities can also be a factor. Citric and acetic acids, found in citrus fruits, tomatoes, and vinegar-based foods, have long been identified as triggers in susceptible people. In some cases, simply avoiding those foods has been enough to bring marked relief.4Journal of Allergy. Canker sores from allergy to weak organic acids (citric and acetic): Case report and clinical study Nutritional deficiencies matter too: people who get recurrent canker sores tend to consume less vitamin B12 and folate than those who don’t.5PubMed Central. Reduced dietary intake of vitamin B12 and folate in patients with recurrent aphthous stomatitis
The Simplest Fix You Might Be Overlooking
Before reaching for any remedy, check your toothpaste. Many commercial toothpastes contain sodium lauryl sulfate (SLS), a foaming agent that can irritate the oral lining and provoke canker sores in people who are prone to them. A systematic review found that switching to an SLS-free toothpaste reduced the number of ulcers, the duration of each episode, and pain levels compared to SLS-containing products.6PubMed. Effect of sodium lauryl sulfate on recurrent aphthous stomatitis: A systematic review SLS has separately been identified as a risk indicator for prolonged oral wound healing.7PubMed Central. The Yin and Yang of Sodium Lauryl Sulfate Use for Oral and Periodontal Health: A Literature Review If you deal with frequent canker sores and haven’t tried this swap, it’s the lowest-effort change with some of the strongest evidence behind it. SLS-free options are widely available and cost about the same as regular toothpaste.
Home Remedies That Have Actual Evidence
Saltwater rinses are the classic go-to, and for good reason. A warm saltwater rinse (about half a teaspoon of salt in a cup of warm water) creates a mild hypertonic environment that draws fluid out of swollen tissue, temporarily reducing inflammation and helping keep the area clean. There is no large trial quantifying the effect, but the mechanism is well understood and the approach is universally safe.
Honey is a more interesting case. An animal study compared two delivery systems for honey on oral ulcers and found that a honey gel formulation was more effective than a mucoadhesive form in shortening wound healing time, with noticeable differences by the third and seventh days.8PubMed Central. Effect of two different delivery systems of honey on the healing of oral ulcer in an animal model Honey has antibacterial and anti-inflammatory properties, and dabbing a small amount of raw honey directly on a canker sore a few times a day is unlikely to cause harm. The evidence is still preliminary but points in a positive direction.
Baking soda rinses are often recommended, but the evidence here is weaker than people assume. A systematic review examining sodium bicarbonate for oral mucositis found no support for its use in treatment or prevention and cautioned that the sudden pH increase it causes could actually delay proper pharmacological treatment.9BMC Oral Health. Prevention and the treatment of oral mucositis: the efficacy of sodium bicarbonate vs other agents: a systematic review That review specifically looked at oral mucositis (mouth sores from cancer treatment), which is not identical to a garden-variety canker sore, but the finding is a useful reality check: baking soda’s reputation as an oral-ulcer remedy is probably overblown.
Over-the-Counter Products Worth Knowing About
If home remedies aren’t cutting it, several pharmacy-aisle options can help. The most common are topical numbing agents containing benzocaine (brand names like Orajel and Anbesol). These work exactly how they sound: they numb the surface of the sore for a short window, making it easier to eat and drink. They do not speed healing, but the temporary pain relief is real and sometimes that’s all you need to get through a meal.
A more targeted option is hyaluronic acid (HA) gel, sold in some countries as an oral wound-care product. HA is a molecule your body naturally produces in connective tissue, and in gel form it creates a protective barrier over the ulcer while promoting tissue repair. A systematic review of clinical trials found that HA was effective at relieving pain and shortening healing time, with no reported side effects. Compared to triamcinolone (a prescription steroid), HA performed comparably in two studies and outperformed it in one.10PubMed. Efficacy of hyaluronic acid for recurrent aphthous stomatitis: a systematic review of clinical trials In a retrospective study, patients using an HA gel saw about an 80% reduction in lesion size after seven days, with more than half achieving complete closure. The gel form showed faster early results than a rinse form, with about 72% of gel users showing improvement by day three compared to 40% of rinse users.11PubMed Central. Treatment of recurrent aphthous stomatitis with a barrier forming mouth rinse or topical gel formulation containing hyaluronic acid: a retrospective clinical study
Chlorhexidine gluconate mouthwash, available over the counter in some markets and by prescription in others, is another option. It’s an antimicrobial rinse commonly used after dental procedures, and case reports suggest that applying it directly to ulcers (via moistened gauze, for example) can lead to healing within about seven days.12Journal of Holistic Nursing Science. A case study of using chlorhexidine gluconate for mouth ulcer care The evidence base for chlorhexidine on canker sores specifically is thinner than for HA, but dentists frequently recommend it as a supplemental rinse for recurrent sores.
Prescription Topical Steroids
When over-the-counter products aren’t enough, the first-line prescription treatment is a topical corticosteroid. These are anti-inflammatory pastes or gels (such as triamcinolone acetonide, fluocinonide, or clobetasol) that you apply directly to the sore. A systematic review of the available trials found that topical corticosteroids shortened healing time and reduced pain compared to placebo.13Acta Otorrinolaringologica (English Edition). Topical Corticosteroids in Recurrent Aphthous Stomatitis. Systematic Review The catch: the evidence on whether topical steroids prevent future outbreaks was inconclusive. They treat the sore you have now but may not stop the next one from coming.
Applying a topical steroid works best when you start early, ideally during the prodromal phase when you feel tingling or burning before the ulcer fully forms. Waiting until the sore is already large and painful means the steroid has to work against a more advanced inflammatory process. Your dentist or doctor can prescribe the appropriate strength based on how frequent and severe your sores tend to be.
In-Office Procedures for Fast Relief
Two procedures available in dental or medical offices can accelerate healing in ways that topical treatments cannot match.
Silver Nitrate Cautery
Silver nitrate cauterization involves touching the ulcer briefly with a silver nitrate stick, which chemically cauterizes the nerve endings on the sore’s surface. The results from randomized controlled trials are consistent on pain but mixed on healing speed. One trial found that 70% of patients treated with silver nitrate had reduced pain severity within a day, compared to just 11% in the placebo group. However, by day seven, healing rates were similar between the two groups (around 83–89%), meaning the procedure primarily helps with pain rather than speeding up tissue closure.14PubMed. Silver nitrate cautery in aphthous stomatitis: a randomized controlled trial A separate trial, though, found a more dramatic healing difference: 60% of cauterized patients had fully healed ulcers by day seven versus 32% in the placebo group, and the treated group’s average healing time was about 2.7 days compared to 5.5 days for placebo.15PubMed. Silver nitrate cauterization: a treatment option for aphthous stomatitis The inconsistency between these two trials likely reflects differences in technique and ulcer severity. Either way, silver nitrate reliably delivers fast pain relief, which for many patients is the primary goal.
Low-Level Laser Therapy
Low-level laser therapy (LLLT), sometimes called photobiomodulation, uses a focused beam of low-energy light to stimulate tissue repair and reduce inflammation. A systematic review and meta-analysis confirmed that LLLT reduces both pain scores and healing time for canker sores.16PubMed Central. Effectiveness of low-level laser therapy in reducing pain score and healing time of recurrent aphthous stomatitis: a systematic review and meta-analysis In one sham-controlled trial, ulcers in the laser-treated group resolved in about three days on average compared to nearly nine days for the sham group, and 28 of 30 patients experienced complete pain relief immediately after the session.17PubMed Central. Efficacy of Low-Level Laser Therapy in Treatment of Recurrent Aphthous Ulcers – A Sham Controlled, Split Mouth Follow Up Study Those numbers are striking. The main downsides are access and cost: not every dental office has the equipment, and LLLT sessions are rarely covered by insurance for this purpose. But if you’re dealing with frequent, debilitating canker sores and your dentist offers it, the evidence is genuinely encouraging.
Systemic Medications for Severe or Chronic Cases
The vast majority of canker sores respond to the topical and procedural approaches described above. Systemic medications, meaning pills rather than gels, are reserved for people with severe or constantly recurring ulcers that don’t respond to anything else. This is especially relevant for people whose canker sores are a symptom of an underlying condition like Behçet’s disease, an autoimmune disorder that causes ulcers in multiple body systems. A clinical review noted that systemic immunosuppressive agents should be used only for refractory or particularly severe oral ulcers due to Behçet’s disease.18PubMed Central. The treatment of chronic recurrent oral aphthous ulcers
Medications in this tier include colchicine, dapsone, and in extreme cases, thalidomide (which carries serious side effects, including birth defects, and is used only under strict medical supervision). These are not drugs you ask your dentist for; they require specialist management, usually by a dermatologist or rheumatologist. If your canker sores are frequent and severe enough that a clinician is considering systemic treatment, they will typically want to rule out underlying autoimmune or gastrointestinal conditions first, since recurrent mouth ulcers can be an early sign of diseases like celiac disease, Crohn’s disease, or lupus.2SpringerLink. Etiopathogenesis of recurrent aphthous stomatitis and the role of immunologic aspects: literature review
Vitamin B12 and Long-Term Prevention
One of the more practical findings for people who get recurrent canker sores involves vitamin B12 supplementation. A review of the available studies found that sublingual B12, particularly at a dose of 1,000 micrograms daily, led to a significant reduction in the number of outbreaks, the number of ulcers per outbreak, and the duration of each ulcer. The effect became most pronounced after about six months of consistent use.19PubMed. Role of vitamin B12 in treating recurrent aphthous stomatitis: A review This held true even in patients whose blood B12 levels were not clinically low, suggesting that the mechanism might go beyond simply correcting a deficiency.
Sublingual B12 is cheap, widely available, and has essentially no toxicity risk at those doses since it’s water-soluble and your body excretes what it doesn’t need. For anyone dealing with canker sores more than a few times a year, a six-month trial of daily sublingual B12 is a low-risk strategy worth discussing with a healthcare provider. It won’t help the sore you have right now, but it might reduce how often the next one shows up.
When a “Canker Sore” Might Be Something Else
Most mouth sores that heal within two weeks are genuinely canker sores and don’t need further workup. But a sore that lasts longer than three weeks, keeps coming back in the same spot, or is accompanied by other symptoms like fever, skin rashes, genital ulcers, or unexplained weight loss deserves medical attention. Oral ulcers can be a presentation of systemic autoimmune and inflammatory conditions, and in some cases the mouth sore is the first clinical sign before other symptoms develop.20PubMed Central. Oral manifestations of systemic autoimmune and inflammatory diseases: diagnosis and clinical management
The confusion between canker sores and cold sores is also worth addressing directly. Cold sores are caused by herpes simplex virus and typically appear on or around the lips, not inside the mouth. Canker sores are not viral, not contagious, and occur only on the soft tissue inside the mouth. If your sore is on the outer lip or the skin around your mouth, it’s more likely a cold sore and requires a different treatment approach (antiviral medication rather than anti-inflammatory). If it’s on your inner cheek, tongue, gum, or the floor of your mouth, you’re almost certainly dealing with a canker sore.
The Role of Oral Microbiome Health
An emerging area of research is the relationship between canker sores and the oral microbiome. Studies have found that the bacterial communities on the cheek lining of people who get recurrent canker sores differ from those of people who don’t, and those differences are most pronounced during active outbreaks.21PubMed Central. The oral microbiota of patients with recurrent aphthous stomatitis Whether the altered microbiome triggers the sore or the sore disrupts the microbiome is still an open question, but the association is consistent enough that researchers are exploring whether restoring microbial balance could reduce recurrence. Oral probiotics designed specifically for the mouth (distinct from gut probiotics) are already on the market, though their effectiveness for canker sore prevention hasn’t been established in rigorous trials yet. It’s an area worth watching, particularly for people whose sores keep coming back despite trying the standard preventive measures.