Aphthous Ulcer Medication: Topical and Systemic Options

Aphthous ulcers, commonly called canker sores, are treated with a range of medications that fall into a rough ladder: mild cases respond to topical treatments like corticosteroid gels and anti-inflammatory pastes, while severe or frequently recurring cases may need systemic drugs such as oral corticosteroids, colchicine, or even biologic therapies. The choice depends on how often the ulcers come back, how large they are, and how much they interfere with eating and speaking. Most people will never need anything beyond a topical agent, but the options get surprisingly deep for the unlucky minority who deal with persistent outbreaks.

Why These Ulcers Happen and Why That Matters for Treatment

Understanding even a little about what drives aphthous ulcers helps explain why the medications work the way they do. The immune system appears to be the main culprit. Research shows that the lining of the mouth in people with recurrent aphthous stomatitis (the clinical name for recurring canker sores) has elevated levels of inflammatory signaling molecules, particularly tumor necrosis factor alpha (TNF-α) and several other pro-inflammatory markers, compared to healthy tissue.¹ In other words, the body’s own immune cells are attacking the mouth lining in an overblown inflammatory response. TNF-α plays a central role: it kicks off inflammation by drawing immune cells to the area and damaging the tissue. Drugs that dial down TNF-α production, like thalidomide and pentoxifylline, have been shown to help, which further confirms that runaway inflammation is the core problem.²

This immune-driven mechanism is why so many aphthous ulcer medications are anti-inflammatory at their core, whether applied directly to the sore or taken as a pill. The goal is always the same: tamp down the inflammatory cascade, relieve pain, and let the tissue heal.

Topical Corticosteroids

For most people, topical corticosteroids are the first medication a dentist or doctor will suggest. These come as gels, pastes, rinses, or adhesive tablets that you apply directly to the ulcer. Common options include triamcinolone acetonide paste, fluocinonide gel, and dexamethasone rinse. A systematic review found that on average, ulcers healed faster and hurt less with topical corticosteroids than with placebo.³

That said, the evidence is not as overwhelming as you might expect. A network meta-analysis comparing multiple topical treatments head-to-head found that for pain specifically, no topical treatment, including corticosteroids, showed a clear statistical advantage over placebo across different time points. The one exception was topical doxycycline, which did show a meaningful advantage in speeding up healing time.⁴ This does not mean topical steroids are useless. Individual trials consistently show benefit, and clinicians widely consider them helpful. But the effect sizes tend to be modest, and the evidence quality across studies is mixed. For a single canker sore that will resolve on its own in a week or two, a topical steroid mostly buys you a few days of faster healing and somewhat less discomfort during those days.

Amlexanox Paste

Amlexanox 5% paste (marketed as Aphthasol in the United States, though availability has been inconsistent in recent years) is one of the few medications specifically developed for aphthous ulcers rather than borrowed from another use. It works through several anti-inflammatory mechanisms, including blocking the release of histamine and leukotrienes and reducing TNF-α activity.⁵

Across multiple large controlled trials involving over a thousand patients, amlexanox paste consistently accelerated healing and shortened the time to complete pain resolution. Patients using it had significantly more healed ulcers by day three compared to those receiving no treatment, and by day four compared to those using a vehicle paste without the active ingredient. Pain relief tracked even faster, with significantly more patients pain-free by day two versus no treatment.⁶ Side effects were rare and mild.⁷

If you can get it, amlexanox is a solid topical option, especially for people who want something other than a steroid. Its availability has fluctuated depending on the market, so ask your pharmacist whether it is currently stocked or can be ordered.

Antiseptic and Antibiotic Rinses

Chlorhexidine mouthwash is commonly recommended as an adjunct treatment. The idea is straightforward: keeping the ulcer clean and reducing the bacterial load may help it heal faster and hurt less. Evidence suggests chlorhexidine rinses may reduce the severity and pain of ulceration, although results on whether they actually prevent new ulcers from forming have been inconclusive.⁸ The same review noted that evidence for tetracycline mouthwash and local analgesics was weak.

In practice, chlorhexidine rinse is cheap, widely available, and unlikely to cause harm beyond temporary taste changes and tooth staining with prolonged use. It is a reasonable add-on to other treatments, especially if you are dealing with multiple ulcers at once, but it is not a standalone cure.

Barrier-Forming Products and Hyaluronic Acid

A different approach to canker sore treatment skips the anti-inflammatory angle entirely and focuses on physically shielding the ulcer from irritation. Barrier-forming products coat the sore with a protective film, reducing pain from contact with food, drinks, and your teeth. Some of these products contain hyaluronic acid, which plays a natural role in tissue repair.

A study comparing a hyaluronic acid mouth rinse and a hyaluronic acid topical gel found that both were effective for treating minor aphthous ulcers, with the gel showing a trend toward faster onset of healing.⁹ Products like Gelclair, a polyvinylpyrrolidone-sodium hyaluronate gel, work on the same barrier principle and are used for oral ulcers of various causes.¹⁰

These products appeal to people who prefer not to use steroids or who need something they can apply frequently throughout the day. They tend to provide immediate comfort but may need reapplication after eating or drinking.

When You Need Systemic Medication

Most canker sores respond to topical treatment or simply resolve on their own. But some people develop what clinicians call complex aphthosis: large ulcers, many ulcers at once, ulcers that last weeks, or outbreaks so frequent that one barely heals before the next appears. For these patients, topical therapies are not enough, and the treatment ladder moves to oral medications.

Oral Corticosteroids

Systemic corticosteroids, typically prednisone, are considered the first-line systemic treatment. They can be used as a short burst at a higher dose (roughly 20 to 40 mg daily for four to seven days, then tapered down) for an acute flare, or at a low maintenance dose (around 5 mg daily for several months) to keep recurrences at bay. Both approaches have shown good results in relieving pain, accelerating healing, and reducing the number of outbreaks.¹¹ The obvious downside is that long-term oral steroid use carries well-known risks, including bone loss, weight gain, elevated blood sugar, and immune suppression. Clinicians try to keep courses as short as possible.

Colchicine and Dapsone

Colchicine, a drug best known for treating gout, has become a go-to option for severe or complex aphthosis. It works by interfering with inflammatory cell function. A review of the literature describes colchicine as a first-line treatment for complex or severe cases, noting that it reliably reduces pain, decreases the number of ulcers, and lengthens the ulcer-free interval between outbreaks without causing major side effects in most patients.¹²

When colchicine alone is not enough, dapsone is often added. One large case series described a therapeutic ladder for complex aphthosis that moved from topical treatments to colchicine, then to colchicine combined with dapsone, and finally to thalidomide for the most refractory cases.¹³ Dapsone requires monitoring with blood tests because it can cause hemolytic anemia in some people, particularly those with a specific enzyme deficiency. Despite this, the colchicine-dapsone combination is considered a reasonable step before resorting to thalidomide.

Thalidomide

Thalidomide is the most potent drug in the aphthous ulcer arsenal. It works largely by accelerating the breakdown of TNF-α, the inflammatory molecule at the heart of the disease.¹⁴ It is effective even when other systemic drugs have failed, but its use is tightly restricted because of its notorious capacity to cause severe birth defects. It can also cause peripheral nerve damage with prolonged use. Thalidomide sits at the top of the treatment ladder, reserved for patients with debilitating disease who have not responded to anything else, and it requires strict prescribing protocols.¹⁵

Biologic and Targeted Therapies

For patients with aphthous ulcers linked to Behçet’s disease or those who fail conventional systemic drugs, newer targeted therapies have emerged. TNF inhibitors (drugs like infliximab and adalimumab) and apremilast (which works by blocking a different inflammatory enzyme called PDE4) have both shown promise.

A study comparing TNF inhibitors to apremilast in patients with Behçet’s disease-related oral ulcers found both treatments substantially reduced the proportion of patients experiencing ulcers. By three months, roughly a third of patients in each group still had ulcers, down from baseline, and by six months that figure dropped further to about a fifth, with no meaningful difference between the two drug classes.¹⁶

Apremilast has also shown benefit outside Behçet’s disease. A case report described a woman with major recurrent aphthous stomatitis involving a persistent ulcer on the back of her throat that had lasted ten months and resisted all conventional treatments. Apremilast cleared the ulcer completely within three months, and she had no new ulcers during eight months of follow-up.¹⁷ This is a single case, not a trial, but it illustrates the potential of targeted therapies for people at the severe end of the spectrum.

Laser Treatment

Low-level laser therapy, sometimes called photobiomodulation, is a non-drug option that has gained traction in dental offices. The idea is that specific wavelengths of light can reduce inflammation and promote tissue healing when applied directly to the ulcer. A systematic review found that laser treatment provided significant immediate pain relief in five out of six studies examined and reduced healing time in five studies.¹⁸ A study in children found that photobiomodulation produced statistically significant improvements in both ulcer size reduction and pain compared to controls at early time points.¹⁹

The catch is that there is no consensus yet on which type of laser, what power setting, or how much energy works best. Different studies use different devices and protocols, making it hard to give a single recommendation. The treatment also requires an in-office visit, which is less convenient than grabbing a tube of paste from the pharmacy. Still, for people who get frequent ulcers and want an alternative to medication, or for children who struggle with topical applications, laser therapy is worth discussing with a dentist who offers it.²⁰

Nutritional Factors

Certain nutritional deficiencies, especially in B vitamins and iron, have been linked to aphthous ulcers for decades. A study comparing the diets of people with recurrent canker sores to national survey data found that those with ulcers consumed less vitamin B12 and folate. The B12 shortfall was relatively small, about 7% below the recommended daily intake, but folate intake was lower by about 20% of the recommended amount.²¹ The researchers suggested that increasing dietary intake or supplementation of these nutrients might help prevent outbreaks.

This does not mean that taking B vitamins will cure canker sores for everyone. But if you get frequent ulcers and your diet is low in leafy greens, legumes, eggs, or meat, it is worth having your levels checked. Correcting a genuine deficiency is low-risk and may reduce how often the ulcers return.

Avoiding Triggers, Especially Sodium Lauryl Sulfate

One of the simplest and best-supported interventions for recurrent canker sores has nothing to do with medication: switching to a toothpaste that does not contain sodium lauryl sulfate (SLS). SLS is a foaming agent found in most commercial toothpastes, and it can irritate the oral mucosa by stripping away the protective mucin layer.

A systematic review found that SLS-free toothpaste significantly reduced the number of ulcers, duration of each ulcer, number of outbreak episodes, and ulcer pain compared to SLS-containing toothpaste.²² An earlier study put numbers on the difference: participants who switched from an SLS-containing toothpaste to an SLS-free one saw their ulcer count drop from about 14 over a three-month period to roughly 5.²³ That is a dramatic reduction from a zero-cost, zero-risk change. SLS-free toothpastes are widely available from several major brands.

Other commonly reported triggers include acidic or spicy foods, physical trauma to the mouth (biting your cheek, aggressive tooth brushing, dental work), stress, hormonal changes, and certain food sensitivities. Keeping a simple diary of outbreaks and potential triggers can help you identify your personal pattern.

When Canker Sores Signal Something Else

Most aphthous ulcers are idiopathic, meaning they happen for no identifiable underlying reason. But oral ulcers can also be a symptom of systemic diseases, and medication choices change depending on the cause. Behçet’s disease, celiac disease, and inflammatory bowel disease (IBD) are among the conditions most commonly associated with mouth ulcers. Oral lesions in IBD patients have been reported in anywhere from 5% to 50% of cases, depending on the study and the type of IBD.²⁴

If your ulcers are unusually large, last longer than three weeks, occur alongside other symptoms like genital ulcers, joint pain, eye inflammation, or chronic diarrhea, or if they started after a new medication, it is worth seeing a doctor to rule out an underlying condition. Treatment in those cases targets the root disease rather than the mouth sore alone. For instance, ulcers driven by celiac disease often improve on a gluten-free diet without any mouth-specific medication.

The Impact on Daily Life

It is easy for people who get an occasional canker sore to underestimate how disruptive frequent outbreaks can be. Research has quantified the toll: patients with active aphthous ulcers report significantly higher levels of mouth pain, discomfort when eating, and difficulty pronouncing words compared to both healthy controls and their own ulcer-free periods.²⁵ Pain during eating scored particularly high, which is unsurprising to anyone who has tried to eat lunch with a raw sore on the inside of their lip.

This matters for treatment decisions. If you get one small ulcer every few months, a tube of over-the-counter paste and some patience is probably all you need. But if outbreaks are frequent enough to affect your weight, your work, or your mood, the evidence supports moving up the treatment ladder rather than simply enduring it. Pain and functional impairment during active ulcers are real and measurable, and effective medications exist at every severity level.

Emerging Drug Delivery Approaches

One persistent frustration with topical canker sore treatments is that they wash away quickly. Saliva, eating, and tongue movement all work against keeping a medication in contact with the ulcer. Researchers are tackling this problem with new delivery systems designed to stick better and release medication over longer periods.

One approach uses dissolvable microneedle patches pressed directly onto the ulcer surface. These tiny needles penetrate the top layer of the mucosa, deliver the drug payload in minutes, then dissolve completely. Early research suggests they can achieve higher local drug concentrations than conventional gels or pastes.²⁶ Another team developed an adhesive gelatin hydrogel loaded with dexamethasone nanoparticles that stays attached to the ulcer site for over five days in saliva, slowly releasing the steroid the entire time. In animal studies, a single application led to rapid ulcer healing.²⁷

Neither of these technologies is available commercially yet, but they point toward a future where treating a canker sore means applying something once and forgetting about it rather than reapplying paste four times a day. For a condition where treatment adherence is one of the biggest practical challenges, better delivery could make a real difference in outcomes.