Most canker sores heal on their own within one to two weeks, but several home strategies can cut that timeline and reduce pain in the meantime. The fastest relief comes from a combination of protecting the sore from further irritation, applying something that reduces inflammation or forms a barrier over the ulcer, and eliminating the triggers that may have caused it. Unlike cold sores, canker sores are not caused by a virus, which changes what treatments make sense and which are a waste of time.
What a Canker Sore Actually Is
A canker sore, known clinically as an aphthous ulcer, is a shallow, round or oval break in the soft tissue inside your mouth. They typically show up on the inner cheeks, lips, tongue, or soft palate. They hurt, sometimes intensely, and they can make eating, drinking, and talking miserable. But they are not infectious and they are not the same thing as a cold sore, which is caused by herpes simplex virus and appears on or around the lips. Research dating back decades has confirmed that canker sores show no viral activity whatsoever, while cold sores consistently yield herpes simplex virus in culture.
The exact cause of canker sores is still debated, but the current understanding points to an immune response that goes slightly haywire at the mucosal surface. Factors that modify this immune response include food sensitivities, vitamin deficiencies, hormonal shifts, gastrointestinal conditions like celiac disease and Crohn’s disease, mechanical injuries from biting your cheek or aggressive brushing, and psychological stress.1SpringerLink. Etiopathogenesis of recurrent aphthous stomatitis and the role of immunologic aspects: literature review There is also a genetic component: people with a family history of recurrent canker sores are more likely to get them, probably because certain gene variations affecting inflammatory signaling run in families.2PubMed Central. Recurrent aphthous stomatitis: genetic aspects of etiology
Home Remedies That Have Actual Evidence
The internet is full of canker sore remedies ranging from sensible to bizarre. A few have been tested in controlled studies, which is worth knowing before you start swishing random things around your mouth.
Honey
Honey is one of the better-supported natural options. An animal study comparing honey gel, a honey adhesive, and no treatment found that the honey gel group healed significantly faster at both the three-day and seven-day marks.3PubMed Central. Effect of two different delivery systems of honey on the healing of oral ulcer in an animal model The key seems to be keeping the honey in contact with the sore, which is easier said than done inside a wet mouth. A thick dab of raw honey applied directly to the ulcer a few times a day, especially before bed when you are less likely to wash it away by eating or drinking, is the practical approach. Medical-grade honey tends to outperform grocery-store honey in wound-healing research, but regular raw honey still has antimicrobial and anti-inflammatory properties that can help.
Licorice
Licorice root extract, specifically the compound glycyrrhizin, has anti-inflammatory and antimicrobial properties. A systematic review of clinical trials found that topical licorice significantly reduced pain, ulcer size, and healing time in people with recurrent canker sores.4PubMed Central. Topical Licorice for Aphthous: A Systematic Review of Clinical Trials The effect appears to be dose-dependent, meaning more concentrated preparations work better. You can find licorice-containing oral patches and gels online and in some health food stores. The licorice used in candy is usually flavored with anise and contains little or no actual licorice root, so do not expect a bag of licorice twists to do anything useful.
Saltwater Rinse
A warm saltwater rinse is probably the most commonly recommended home remedy, and for good reason. It is essentially free, widely available, and unlikely to cause harm. Dissolving about half a teaspoon of salt in a cup of warm water and swishing gently for 30 seconds creates a mildly hypertonic environment that draws fluid from inflamed tissue, temporarily reducing swelling. It also helps keep the area clean. The evidence for saltwater is mostly clinical tradition rather than controlled trials, but the risk-to-benefit ratio is excellent. You can repeat this several times a day.
What to Skip
Hydrogen peroxide is sometimes suggested for canker sores, but case reports have documented that rinsing with even standard 3% hydrogen peroxide can cause oral ulcerations on its own.5PubMed. Oral ulcerations with use of hydrogen peroxide Putting something that causes mouth ulcers on an existing mouth ulcer is obviously counterproductive. Baking soda pastes are another popular suggestion, and while they are not harmful, the evidence for any meaningful acceleration of healing is thin. If you want alkaline relief, a baking soda rinse (a teaspoon dissolved in water) is gentler than pasting it directly onto the sore.
Over-the-Counter Products Worth Trying
If home remedies alone are not cutting it, pharmacy shelves offer several options that can meaningfully speed things up.
Benzocaine gels and liquids (sold under brand names like Orajel and Anbesol) are topical anesthetics that numb the area on contact. They do not heal the sore faster, but they can make eating tolerable, which matters when a sore on your tongue or inner lip makes every meal painful. The numbing effect wears off within 30 to 60 minutes, so you may need to reapply frequently.
Mucoadhesive patches offer a different approach. They physically cover the ulcer, shielding it from food, saliva, and friction while delivering active ingredients slowly. One randomized trial compared a mucoadhesive patch containing citrus oil and magnesium salts (applied once daily) against a benzocaine oral solution (applied three times daily) and found the patch dramatically outperformed the solution: average healing time was about 36 hours with the patch versus roughly 135 hours with the benzocaine solution.6PubMed Central. Efficacy of a mucoadhesive patch compared with an oral solution for treatment of aphthous stomatitis Pain scores at 12 and 24 hours were also significantly lower in the patch group. The barrier effect of physically covering the sore appears to matter as much as whatever active ingredient the patch contains.
Antimicrobial mouthwashes containing chlorhexidine can help prevent secondary bacterial infection of the ulcer, which sometimes delays healing. These are available over the counter in many countries, though in some places they require a prescription. Chlorhexidine mouthwash can stain teeth with prolonged use, so it is best reserved for active outbreaks rather than daily prevention.
Eliminating Triggers to Speed Healing
Getting rid of a canker sore faster is partly about treating it and partly about stopping whatever keeps aggravating it. Some triggers are well-established enough to be worth addressing immediately.
Switch Your Toothpaste
Sodium lauryl sulfate (SLS) is a foaming agent found in most commercial toothpastes. A systematic review that pooled data from multiple trials found that switching to an SLS-free toothpaste significantly reduced the number of canker sores, how long they lasted, the number of recurrent episodes, and the pain they caused.7PubMed. Effect of sodium lauryl sulfate on recurrent aphthous stomatitis: A systematic review If you get canker sores regularly, this single change may be the most impactful thing you can do. SLS-free toothpastes are widely available; check the ingredients list for “sodium lauryl sulfate” or “SLS.” Many natural toothpaste brands omit it, and some mainstream brands now offer SLS-free lines.
Watch Acidic Foods
Citric acid and acetic acid in foods can directly provoke canker sores in susceptible people. Clinical testing has shown that applying citric acid crystals to the oral mucosa of sensitive individuals reliably reproduced ulcers, while controls showed no reaction. Avoiding foods containing the triggering acids led to significant relief.8Journal of Allergy. Canker sores from allergy to weak organic acids (citric and acetic): Case report and clinical study In practical terms, this means tomatoes, citrus fruits and juices, vinegar-heavy dressings, and carbonated beverages. You do not necessarily need to avoid these permanently, but while you have an active sore, they will cause pain and may slow healing. Spicy foods irritate canker sores for similar reasons, even if they did not cause them.
Manage Stress
The connection between stress and canker sores is not just anecdotal. Research measuring salivary cortisol (a biological marker of stress) found that people with recurrent canker sores had significantly higher cortisol and anxiety levels compared to controls, with a strong positive correlation between the two.9PubMed Central. Relationship of salivary cortisol and anxiety in recurrent aphthous stomatitis This does not mean you can meditate a canker sore away overnight, but it does explain why outbreaks tend to cluster around stressful periods like exams, job changes, or personal crises. Addressing chronic stress and sleep deprivation can reduce how often sores appear and may help the current one resolve faster.
Nutritional Gaps That Keep Sores Coming Back
If you get canker sores repeatedly, a nutritional deficiency could be part of the picture. The nutrients most consistently linked to recurrent canker sores are vitamin B12 and folate. Research has shown that people with recurrent aphthous ulcers not only tend to have lower blood levels of B12 and folate, but actually consume less of these nutrients than the general population.10PubMed Central. Reduced dietary intake of vitamin B12 and folate in patients with recurrent aphthous stomatitis Iron and zinc deficiencies have also been implicated, though the evidence is less robust.
B12 supplementation has been studied as a treatment even in people whose blood levels are technically within the normal range. A trial found that sublingual B12 supplements reduced the number and duration of canker sore outbreaks over several months.11PubMed. Cyanocobalamin may be beneficial in the treatment of recurrent aphthous ulcers even when vitamin B12 levels are normal The practical takeaway: if you get canker sores frequently and your diet is low in animal products, leafy greens, or fortified foods, a B-complex supplement is cheap and worth trying. It will not heal the sore you have right now overnight, but it may prevent the next one.
Probiotics have also shown some promise. A meta-analysis found that probiotic supplementation significantly reduced oral pain associated with canker sores compared to placebo, though it did not significantly reduce overall ulcer severity.12Scientific Reports. The efficacy of probiotics in management of recurrent aphthous stomatitis: a systematic review and meta-analysis The mechanism probably involves modulating the oral microbiome and local immune response. As a pain-relief strategy during an active sore, probiotics are slow-acting; as a long-term prevention approach for frequent sufferers, they may be worth incorporating.
When Home Remedies Are Not Enough
Some canker sores are large, deeply painful, or in locations (like the throat or base of the tongue) where home treatments are hard to apply. In those cases, clinical treatments can provide dramatically faster relief.
Prescription corticosteroid pastes, particularly triamcinolone acetonide, are one of the most commonly used clinical treatments. This is a topical steroid that suppresses the local immune response driving the ulcer. A meta-analysis of randomized controlled trials found that triamcinolone acetonide was more effective than several alternative treatments at reducing ulcer size and shortening healing time, though the advantage over placebo for pain reduction alone was less clear.13PubMed Central. Effectiveness of 0.1% triamcinolone acetonide compared with those of other therapies for minor recurrent aphthous stomatitis: a systematic review and meta-analysis of randomized controlled trials It works best when applied early in the sore’s life, before the ulcer has fully formed. You apply a small amount directly to the sore and try not to eat or drink for 30 minutes afterward. Your dentist or doctor can prescribe this, and it is worth asking about if over-the-counter options keep falling short.
Silver nitrate cauterization is another option that sounds medieval but delivers fast results. A controlled trial found that a single application of silver nitrate to the ulcer produced complete healing in about 60% of patients by day seven, compared to about 32% in the control group. Among those who healed, the silver nitrate group’s average healing time was roughly 2.7 days versus 5.5 days for controls, and pain scores were significantly lower from the very first day after treatment.14PubMed. Silver nitrate cauterization: a treatment option for aphthous stomatitis The application itself stings briefly but destroys the nerve endings at the ulcer surface, which is why pain drops so quickly afterward. Silver nitrate sticks are available at some pharmacies, though having a clinician do it reduces the risk of damaging surrounding tissue.
Low-level laser therapy is an option gaining traction in dental offices. The laser energy reduces inflammation and promotes tissue repair, and case reports describe rapid pain relief and full resolution of ulcers following treatment.15PubMed Central. Low laser therapy as an effective treatment of recurrent aphtous ulcers: a clinical case reporting two locations The evidence base is still developing compared to silver nitrate or corticosteroids, but the treatment is painless and has essentially no side effects, making it appealing if your dentist offers it.
When to See a Doctor Instead of Treating at Home
Most canker sores are minor annoyances that resolve within a couple of weeks regardless of what you do. But some patterns signal something more serious than a garden-variety aphthous ulcer.
See your doctor or dentist if a sore lasts longer than three weeks, if you develop unusually large sores (bigger than about a centimeter across), if new sores keep appearing before old ones have healed, if the sores come with a high fever, or if you are getting them so frequently that you are rarely without one. These patterns can signal an underlying systemic condition rather than simple recurrent canker sores.
One condition your doctor will want to rule out is Behçet’s disease, a systemic inflammatory disorder in which aphthous-like mouth ulcers appear alongside genital ulceration and eye problems, particularly a type of inner-eye inflammation.16PubMed. Oral mucosal disease: recurrent aphthous stomatitis Canker sores are also sometimes the first noticeable sign of celiac disease, Crohn’s disease, or other gastrointestinal conditions. If you have persistent ulcers alongside digestive symptoms, unexplained weight loss, or chronic fatigue, those dots are worth connecting with a healthcare provider.
Rarely, what looks like a canker sore that will not heal turns out to be oral cancer. Cancerous mouth ulcers tend to be painless, irregularly shaped, and located on the lateral border of the tongue or floor of the mouth. Any single ulcer that persists for more than three weeks without improvement deserves professional evaluation, regardless of whether it hurts.
A Practical Healing Timeline
Knowing roughly what to expect helps you decide whether your sore is following a normal trajectory or whether you should escalate treatment. A typical minor canker sore goes through a predictable sequence. For the first day or two you feel a tingling or burning sensation before the ulcer is even visible. This prodromal phase is actually the best time to intervene: applying a corticosteroid paste or mucoadhesive patch during this window can sometimes prevent the ulcer from fully forming.
Once the sore appears, pain usually peaks around days three through five. This is when home remedies and OTC treatments provide the most noticeable relief. The ulcer then begins to shrink and the pain fades. Full healing for a minor sore typically takes seven to fourteen days. Major aphthous ulcers (the deeper, larger kind) can take four to six weeks and sometimes leave a scar, which is another reason to seek clinical treatment for larger sores rather than toughing it out.
If you layer multiple strategies, you can reasonably hope to shave several days off the typical timeline. Switching to an SLS-free toothpaste, rinsing with salt water a few times a day, applying honey or a licorice-based product to the sore, covering it with a mucoadhesive patch when eating, and avoiding acidic or spicy foods is a sensible combination. None of these approaches conflict with each other, and together they address irritation, inflammation, and bacterial contamination simultaneously. For sores that are large or excruciating, skip straight to asking for a corticosteroid paste or silver nitrate treatment. The research on silver nitrate in particular suggests it delivers the fastest measurable acceleration of healing of any available option.