What to Do for a Canker Sore: Treatments That Help

Most canker sores heal on their own within one to two weeks, but the right treatment can cut pain and shorten that timeline. The options range from simple over-the-counter numbing gels to prescription anti-inflammatory pastes, with several home remedies and trigger-avoidance strategies filling in between. What works best depends on how often you get canker sores, how large they are, and how much they interfere with eating and talking.

Topical Numbing Agents for Immediate Pain Relief

When a canker sore is making it hard to eat or brush your teeth, the fastest relief comes from a topical anesthetic. Viscous lidocaine, available by prescription, has been used for decades specifically for painful oral mucosal lesions and provides temporary numbing of the area.¹ Over-the-counter options containing benzocaine (sold under brand names like Orajel and Anbesol) work on the same principle. You apply the product directly to the sore, and within a minute or two the area goes numb for anywhere from 15 minutes to an hour depending on the formulation.

These products do not speed healing. Their entire purpose is pain management so you can get through meals and oral hygiene without wincing. If you use a numbing gel before brushing, you are more likely to brush thoroughly, which actually helps the sore heal by keeping bacteria at bay. Just avoid swallowing too much of a lidocaine-based product, since it can numb the throat and make swallowing feel strange.

Barrier-Forming Rinses and Gels

A newer category of over-the-counter treatments creates a physical barrier over the ulcer, shielding it from food, saliva, and friction. Products containing hyaluronic acid, in both mouth-rinse and gel form, have shown real results in clinical use. In a retrospective study, both a hyaluronic acid rinse and a hyaluronic acid gel led to roughly 77 to 81 percent lesion reduction after seven days, with complete closure in over half the cases. The gel had an edge in early response: about 72 percent of sores treated with the gel showed improvement by day three, compared with 40 percent in the rinse group.²

The practical takeaway is that if you prefer a rinse because it is easier to apply to hard-to-reach spots (the back of the tongue, the soft palate), it still works well by the end of a week. But if you want faster improvement and the sore is somewhere you can dab a gel onto with a clean finger or cotton swab, the gel format may be worth choosing instead.

Corticosteroid Pastes

Triamcinolone acetonide in an oral paste (often sold as Kenalog in Orabase) is one of the most commonly prescribed treatments for canker sores. It works by tamping down the inflammatory response at the ulcer site, and paste formulations are specifically designed to stick to the wet surface of the mouth long enough for the drug to absorb.³

The evidence on how much triamcinolone actually helps is more mixed than many people expect. A systematic review and meta-analysis of randomized trials found that while 0.1 percent triamcinolone acetonide reduced ulcer size and shortened healing time compared with some alternative treatments, it showed no clear advantage over placebo in pain reduction or healing time.⁴ A separate network meta-analysis comparing many topical medications head to head found no statistically significant differences among them for pain reduction, and most topical treatments performed similarly to placebo on that measure. Doxycycline was the one exception, showing a real advantage in healing time.⁵

This does not mean corticosteroid pastes are useless. They can reduce the physical size of the sore faster, and many people do report subjective relief. But if you have been relying on triamcinolone and feel like it is not doing much for pain specifically, the research suggests you are not imagining things. A barrier gel or a numbing agent may serve you better on the pain front.

Amlexanox Paste

Amlexanox (marketed as Aphthasol in the United States, though availability has fluctuated) is a prescription anti-inflammatory paste that works differently from corticosteroids. Rather than broadly suppressing the immune response, it blocks the release of histamine and certain inflammatory molecules from immune cells at the ulcer site.⁶

The clinical evidence for amlexanox is relatively strong for a canker sore treatment. Across four large trials, applying the five percent paste consistently accelerated complete healing and reduced the time it took for pain to resolve. Patients using amlexanox had significantly more healed ulcers by day three compared with no treatment, and by day four compared with a vehicle paste. Pain improvement followed a similar pattern, with more patients reporting complete pain resolution starting at day two.⁷ If your canker sores are frequent and disruptive enough that you are willing to get a prescription, amlexanox is one of the better-supported options.

Home Remedies Worth Trying

Salt water rinses are the classic home treatment, and they have genuine logic behind them. A warm saline rinse is mildly antiseptic, draws fluid out of swollen tissue through osmosis, and keeps the area cleaner. It will sting briefly on contact, but many people find the soreness improves afterward. A half teaspoon of salt in a cup of warm water, swished for 30 seconds a few times a day, is the standard approach. Baking soda rinses work similarly and are slightly less irritating if salt stings too much.

Honey is another home remedy that has moved past folk-wisdom status into early research. In an animal study, honey gel applied to oral ulcers accelerated healing more effectively than a mucoadhesive form of honey, showing significant improvement in both visual and tissue-level markers by the third and seventh days.⁸ Honey has well-documented antibacterial and anti-inflammatory properties, and dabbing a small amount of raw honey directly on a canker sore a few times a day is low-risk. The evidence is still preliminary, but it is stronger than what exists for most other kitchen-cabinet remedies.

Products like Milk of Magnesia (magnesium hydroxide) applied directly to the sore are sometimes recommended as well. The alkaline coating may neutralize acids from food and provide a mild protective layer. It will not dramatically change healing time, but as a comfort measure it is inexpensive and harmless.

Switching Your Toothpaste

This is one of the most underappreciated changes you can make if you get canker sores regularly. Sodium lauryl sulfate (SLS), the foaming agent in most commercial toothpastes, has been linked to canker sore flare-ups for years. A systematic review pooling data from eligible trials found that switching from an SLS-containing toothpaste to an SLS-free one significantly reduced the number of ulcers, the duration of each episode, the number of episodes, and ulcer pain.⁹ That is a meaningful improvement across every measure researchers tracked.

SLS-free toothpastes are easy to find (Sensodyne, Biotene, and several others skip SLS), so this is a change you can make tonight. If you have been getting canker sores every month or two and have not tried an SLS-free toothpaste, it is worth a trial of a few months to see if your outbreak frequency drops.

Nutritional Deficiencies That Keep Canker Sores Coming Back

People who get recurrent canker sores consume lower amounts of vitamin B12 and folate compared with the general population, according to a study that compared the diets of canker sore patients against national nutrition survey data. Both nutrients were significantly lower in the canker-sore group.¹⁰ Iron and zinc deficiencies have also been flagged in the broader literature on the condition.

The underlying cause of canker sores is considered multifactorial, with immune-system disturbances playing a central role. Vitamin and microelement deficiencies are among the factors thought to modify the immune response involved, alongside food sensitivities, hormonal changes, gastrointestinal disorders like celiac disease and Crohn’s disease, mechanical injuries, and stress.¹¹ If you get canker sores frequently, it is reasonable to ask your doctor to check your B12, folate, iron, and zinc levels. Supplementing a genuine deficiency can sometimes reduce outbreaks, though it is unlikely to eliminate them entirely if other triggers are also at play.

The Role of Stress, Sleep, and Mechanical Trauma

Stress is one of the most commonly reported triggers, and the biological mechanism has some backing. In an animal model, sleep deprivation worsened existing oral ulcers and delayed healing, while also raising levels of stress hormones and inflammatory markers in both the blood and the oral tissue itself.¹² The implication for humans is that the usual advice about managing stress and getting adequate sleep is not just hand-waving. Chronic stress and poor sleep ramp up inflammation systemically, and the thin, vulnerable tissue inside the mouth seems to take the hit.

Mechanical trauma is another major trigger. Biting the inside of your cheek, poking yourself with a sharp chip, or getting scratched by braces or a rough dental appliance can all set off a canker sore in someone who is prone to them.¹³ If you notice that your sores tend to appear in the same spot where a bracket rubs or where you habitually chew your lip, addressing the physical irritation can prevent recurrences more effectively than any medication after the fact. Orthodontic wax on braces and smoothing any sharp tooth edges with your dentist are simple, underrated interventions.

Low-Level Laser Therapy

If you have access to a dentist or oral medicine specialist with the right equipment, low-level laser therapy is an option that delivers impressively fast pain relief. In a sham-controlled study of 30 patients, complete pain relief was observed immediately after laser application in 28 of 30 treated patients, and overall healing time was also reduced.¹⁴ Other clinical reports have confirmed that diode lasers can achieve both pain relief and complete remission of oral ulcers.¹⁵

The practical barrier is availability. Not every dental office has a diode laser, and not every practitioner is trained in this specific application. Insurance coverage varies. But for someone who gets large, severely painful, or slow-healing canker sores regularly, it is worth asking whether your dentist offers it. The treatment itself is quick, painless, and has no meaningful side effects.

Systemic Medications for Severe Cases

When canker sores are frequent, large, or unresponsive to topical treatments, doctors sometimes consider systemic medications. Options that have been used include colchicine (an anti-inflammatory originally developed for gout), pentoxifylline, and oral prednisolone (a systemic corticosteroid). However, the evidence supporting systemic treatment is debated, and stronger immunosuppressive agents are generally reserved for cases tied to Behçet’s disease or other underlying systemic conditions.¹⁶

The risk-benefit calculation shifts significantly with systemic drugs. Colchicine can cause gastrointestinal side effects, and immunosuppressants carry their own set of concerns. These are not first-line options for the person who gets a canker sore once every couple of months. They exist for the small subset of patients who develop major aphthous ulcers (larger than a centimeter), who get them in clusters of five or more at a time, or whose sores persist for weeks without healing.

Canker Sores Are Not Cold Sores

This confusion persists partly because both occur in or around the mouth and both hurt. But they are fundamentally different. Cold sores (fever blisters) are caused by the herpes simplex virus and appear on the outside of the lips or the border of the lip and skin. Canker sores occur inside the mouth on non-keratinized tissue like the inner cheek, tongue, and soft palate, and they are not caused by any virus. Early research culturing tissue from 100 canker sores found zero viral activity, while cultures from herpetic lesions readily grew herpes simplex virus.¹⁷

The distinction matters for treatment. Antiviral medications like acyclovir and valacyclovir, which work well for cold sores, do nothing for canker sores. If you have been applying cold sore cream to a sore inside your mouth and wondering why it is not helping, the odds are good that you are treating the wrong condition. Canker sores are an immune-mediated inflammatory process, not an infection, which is why anti-inflammatory and barrier-forming treatments are the appropriate tools.

Hormonal Triggers and What the Evidence Actually Shows

Many people notice canker sores flaring around their menstrual period or during pregnancy, which has led to a long-standing assumption that hormonal changes are a direct trigger. The picture is murkier than it seems, though. A large-scale genetic analysis testing whether estradiol levels have a causal relationship with mouth ulcers found no evidence of one, in either men or women.¹⁸ This does not mean people are imagining the timing. It suggests that what is happening around the menstrual cycle (stress, sleep disruption, immune fluctuations, dietary changes) may be responsible rather than estrogen itself driving the ulcers. It is a useful distinction because it means focusing on stress management and sleep around vulnerable times in the cycle may help more than assuming the sores are a hormonal inevitability you cannot influence.

Putting Together a Personal Approach

Since canker sores have multiple contributing causes, the most effective strategy usually combines a treatment for the sore you have right now with prevention measures aimed at reducing future outbreaks. For the active sore, a topical numbing agent or barrier gel handles pain while the ulcer heals. If you want to actively speed healing, amlexanox paste has the best trial evidence, though access varies by country and prescription availability. For prevention, switching to an SLS-free toothpaste is the single easiest change with solid evidence behind it. Beyond that, checking for nutritional deficiencies, managing stress and sleep, and reducing mechanical irritation from dental appliances or aggressive brushing can each make a measurable difference.

If a canker sore has not healed after three weeks, is unusually large, comes with a fever, or keeps recurring in the same spot, it is worth seeing a dentist or doctor. Persistent or unusual ulcers occasionally signal an underlying condition like celiac disease, Crohn’s disease, or Behçet’s disease, and rare cases require biopsy to rule out something more serious. For the vast majority of people, though, canker sores are a painful nuisance with a shelf life, and the treatments above can make that shelf life shorter and more bearable.