Most mouth sores heal on their own within one to two weeks, but you can speed things along and cut the pain considerably with the right treatment. What that treatment looks like depends on what kind of sore you have. The vast majority of mouth sores people deal with are canker sores (aphthous ulcers), small shallow ulcers on the inner cheeks, gums, or tongue that are not contagious. A smaller share are cold sores caused by the herpes simplex virus, which cluster on or near the lips and require a completely different approach. Figuring out which one you’re dealing with is the first step toward getting rid of it.
Figuring Out What Kind of Sore You Have
Canker sores and cold sores are commonly confused, but they behave differently and respond to different treatments. In clinical samples of patients presenting with oral sores, roughly nine out of ten turn out to be canker sores, with cold sores making up most of the remainder. Canker sores appear inside the mouth as round or oval ulcers with a whitish or yellowish center and a red border. They are not caused by a virus and cannot be spread to anyone else. Cold sores, on the other hand, usually show up as clusters of small fluid-filled blisters on the outer edge of the lips or just outside the mouth. They are caused by herpes simplex virus and are contagious, especially when the blisters are open.
There are also less common causes of mouth sores. Trauma from braces, dentures, or accidental biting can produce ulcers that look like canker sores but are purely mechanical. In one study of orthodontic patients, over three-quarters reported small wounds from their fixed appliances during treatment.1PubMed. Traumatic ulcers and pain during orthodontic treatment Certain medications, particularly some antidepressants and chemotherapy drugs, can also trigger oral ulcers that won’t respond to standard canker-sore treatments.2PubMed Central. Ulceration of the oral mucosa induced by antidepressant medication: a case report Getting the cause right matters because the fix is different for each one.
Over-the-Counter Options for Canker Sores
If you have a standard canker sore, you don’t necessarily need a prescription. Several over-the-counter products can reduce pain and help the ulcer close faster. Barrier-forming gels and rinses containing hyaluronic acid, for example, showed significant wound reduction in a clinical study: after seven days, ulcer size shrank by roughly 77 to 81 percent on average, and more than half of patients had complete closure.3PubMed 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 The gel formulation worked faster early on, with nearly three-quarters of treated ulcers improving within three days, compared to about 40 percent in the rinse group.
Other widely available options include benzocaine-based numbing gels (the active ingredient in products like Orajel), antiseptic rinses, and over-the-counter pastes that coat the sore and protect it from irritation while you eat and talk. A simple saltwater rinse, made with about half a teaspoon of salt in a cup of warm water, is an old standby that helps keep the area clean and can ease discomfort. These measures won’t prevent future outbreaks, but they take the edge off while your body does the healing.
Prescription Treatments for Persistent or Severe Ulcers
When canker sores are large, unusually painful, or keep coming back, a dentist or doctor may prescribe a topical corticosteroid. A systematic review of studies on these medications found that, on average, ulcers healed faster with topical corticosteroids than with placebo, and patients experienced less pain during the healing period.4Acta Otorrinolaringologica (English Edition). Topical Corticosteroids in Recurrent Aphthous Stomatitis. Systematic Review One commonly prescribed option is triamcinolone acetonide paste, which you apply directly to the sore. In a comparison trial, triamcinolone paste brought down pain scores faster than an alternative topical treatment during the first five days of use.5Journal of Indian Academy of Oral Medicine and Radiology. Correlation of Pain Score with Ulcer Size in Oral Aphthous Ulcers Using 2% Curcumin Gel and 0.1% Triamcinolone Oral Paste – A Parallel Comparison Study
One important caveat: topical steroids are designed for canker sores, not for every type of oral ulcer. If an ulcer doesn’t improve after a week or two on a topical steroid and shows no signs of anything more serious, the cause may be a medication you’re taking rather than a garden-variety canker sore. In that scenario, the right move is to check with the prescribing doctor about switching drugs or adjusting the dose. After stopping or changing the offending medication, ulcers often clear within a week or two.6Japanese Dental Science Review. Oral ulcerations due to drug medications
Cold Sores Need a Different Playbook
If your sore is a cold sore rather than a canker sore, anti-inflammatory pastes won’t do much. Cold sores are caused by herpes simplex virus, and the most effective treatments are antiviral medications. The sooner you start them after the first tingle, the better they work.
Valacyclovir, taken orally, is one of the strongest options. In two large placebo-controlled trials, a one-day course of valacyclovir shortened the average cold sore episode by about a day and significantly reduced both healing time and pain duration compared to placebo.7PubMed Central. High-dose, short-duration, early valacyclovir therapy for episodic treatment of cold sores: results of two randomized, placebo-controlled, multicenter studies For people who prefer a topical approach, penciclovir cream applied directly to the blister has been shown to outperform topical acyclovir cream, producing a faster reduction in lesion area, healing time, and pain.8Skin Pharmacology and Physiology. Penciclovir Cream – Improved Topical Treatment for Herpes simplex Infections Newer formulations that combine acyclovir with a corticosteroid have also shown promise, shortening recovery and scabbing times compared to standard acyclovir cream alone.9PubMed Central. Therapeutic effects of acyclovir and acyclovir-clobetasol nanofibers vs. cream formulation for recurrent herpes labialis
Topical penciclovir cream is available over the counter in many countries, while valacyclovir typically requires a prescription. If you get cold sores frequently, keeping a supply of your preferred antiviral on hand so you can start treatment at the first sign of a tingle makes a meaningful difference in how bad the outbreak gets.
Home Remedies That Have Some Evidence
Honey is one home remedy with genuine clinical support. In a randomized controlled trial involving children with chemotherapy-related mouth sores, those who received honey had significantly less severe oral ulceration and less pain than those who received standard care alone. Olive oil also reduced pain, though not as effectively as honey. These findings are specific to mucositis in cancer patients, so the results aren’t perfectly generalizable to everyday canker sores, but honey’s anti-inflammatory and antimicrobial properties make it a reasonable low-risk option for mild ulcers.
Other home approaches people commonly use include applying a dab of milk of magnesia to the sore, rinsing with a baking soda solution, or placing a wet black tea bag against the ulcer (the tannins may have a mild astringent effect). None of these has the same level of clinical evidence as the products discussed above, but they’re unlikely to cause harm and may help with comfort while you wait for healing.
Preventing Mouth Sores From Coming Back
If you get canker sores repeatedly, the better question isn’t just how to treat each one but how to stop them from showing up in the first place. Several modifiable factors play a role.
Switch to an SLS-Free Toothpaste
Sodium lauryl sulfate (SLS) is the foaming agent in most toothpastes, and it’s a known irritant to oral tissue. A systematic review of clinical trials found that people who switched to an SLS-free toothpaste experienced fewer ulcers, shorter episodes, and less pain compared to those using standard SLS-containing toothpaste.10PubMed. Effect of sodium lauryl sulfate on recurrent aphthous stomatitis: A systematic review This is one of the simplest changes you can make. Several widely available brands sell SLS-free formulations, often marketed for sensitive mouths.
Watch for Dietary Triggers
Certain foods seem to provoke canker sores in susceptible people. Citric acid and acetic acid have long been identified as triggers in some patients; avoiding foods containing those acids led to marked relief of ulcers in a clinical study.11Journal of Allergy. Canker sores from allergy to weak organic acids (citric and acetic): Case report and clinical study Cow’s milk protein is another underappreciated trigger. In one report, two children with five-year histories of frequent canker sores became completely ulcer-free within two weeks of stopping dairy, and one child’s ulcers returned when dairy was reintroduced.12PubMed. Resolution of recurrent aphthous ulcers after discontinuation of cow’s milk protein intake If you can’t identify an obvious trigger, keeping a simple food diary for a few weeks while tracking outbreaks can help you spot patterns.
Address Nutritional Gaps
Low intake of vitamin B12 and folate has been linked to recurrent canker sores. In one study, people with recurring ulcers consumed significantly less dietary B12 and folate than the general population, even though their intake of most other nutrients was actually above average.13PubMed Central. Reduced dietary intake of vitamin B12 and folate in patients with recurrent aphthous stomatitis A review of randomized trials on B12 supplementation found that higher-dose sublingual B12 (around 1,000 micrograms daily) led to a meaningful reduction in the number, duration, and frequency of ulcer outbreaks, especially after about six months of use.14PubMed. Role of vitamin B12 in treating recurrent aphthous stomatitis: A review This doesn’t mean B12 deficiency is the cause of every canker sore, but if you get them often, it’s worth having your levels checked.
Manage Stress
Stress is one of the most consistent triggers for canker sore outbreaks. In a study tracking ulcer episodes alongside life events, experiencing a stressful event nearly tripled the odds of a canker sore flare. Mental stressors had a larger effect than physical ones.15PubMed Central. Effect of stressful life events on the onset and duration of recurrent aphthous stomatitis Stress didn’t seem to make individual ulcers last longer once they appeared, but it clearly made them more likely to appear in the first place. If your outbreaks cluster around exams, deadlines, or difficult personal stretches, that’s probably not a coincidence.
When Mouth Sores Show Up in Children
Children get mouth sores from many of the same causes adults do, but one condition that’s almost exclusively a childhood issue is hand, foot, and mouth disease (HFMD). Caused by enteroviruses, it produces painful oral ulcers along with a rash on the hands and feet, typically in kids under five.16PubMed Central. Current status of hand-foot-and-mouth disease The mouth sores can make eating and drinking miserable for toddlers, which is the main concern because dehydration is the biggest practical risk.
HFMD is self-limiting, meaning it resolves on its own without specific medication, usually within a week. There is no antiviral that targets it.17PubMed Central. Managing hand-foot-mouth disease in children: More of counseling, less of medicines Management centers on keeping the child comfortable: offering cold fluids and soft foods, using age-appropriate pain relievers, and watching for signs of dehydration. The oral ulcers from HFMD look different from canker sores because they often appear alongside a distinctive rash, and they occur in the context of a mild fever and general malaise. If your child develops mouth sores together with spots on their palms and soles, HFMD is the likely culprit, and the main job is supportive care while the virus runs its course.
Laser Therapy for Severe or Frequent Ulcers
For people who deal with stubborn or frequently recurring canker sores that don’t respond well enough to topical treatments, low-level laser therapy (LLLT) is an option worth knowing about, though it’s less widely available. A systematic review found that laser treatment provided significant pain relief immediately after the session in most studies and also shortened healing time.18PubMed. Effect of laser on pain relief and wound healing of recurrent aphthous stomatitis: a systematic review A more recent meta-analysis confirmed these findings, concluding that both pain scores and healing time were reduced after LLLT.19PubMed 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 treatment uses a low-energy diode or similar laser applied directly to the ulcer and is painless. It’s typically offered at dental clinics that specialize in oral medicine. The main barrier is access and cost, since it isn’t yet a standard first-line recommendation and may not be covered by insurance.
Why Mouth Sores Heal Relatively Fast
One reassuring fact about mouth sores is that the oral lining is inherently good at healing. Compared to skin, the oral mucosa closes wounds faster, produces less scarring, and mounts a quicker immune response. Researchers attribute this to several factors: saliva constantly bathes the tissue with growth factors and antimicrobial compounds, the resident cells in the mouth divide more rapidly, and the extracellular scaffolding that supports new tissue gets remodeled more efficiently.20PubMed Central. The Bigger Picture: Why Oral Mucosa Heals Better Than Skin This is why even a painful canker sore that feels enormous typically closes up within one to two weeks without any treatment at all.
That healing advantage has a flip side, though. The oral environment is teeming with bacteria, and when the microbial balance gets disrupted, it can actually accelerate mucosal damage and make ulcers more likely to form or slower to resolve.21PubMed Central. Oral microbiota dysbiosis accelerates the development and onset of mucositis and oral ulcers This helps explain why illness, heavy antibiotic use, or poor oral hygiene can seem to invite mouth sores. Keeping your mouth clean and your overall health steady supports the same biology that makes oral healing so efficient.
The Surprising Link Between Quitting Smoking and Mouth Ulcers
Here’s something people rarely expect: quitting smoking often triggers a wave of mouth ulcers. In one study, about 40 percent of people who stopped smoking developed mouth ulcers, mostly within the first two weeks of quitting.22PubMed. The relationship between smoking cessation and mouth ulcers The problem was generally mild, but about 8 percent of those affected reported severe ulceration. In most people, the ulcers resolved within four weeks. A separate study confirmed the pattern, finding a significant increase in reported mouth ulcers at one and two weeks after quitting.23Tobacco Control. Increase in common cold symptoms and mouth ulcers following smoking cessation
The likely explanation involves the effect nicotine has on the oral lining. Smoking thickens the outer layer of the oral mucosa over time, and it also suppresses certain immune responses. When you quit, the tissue thins back to its normal state and the immune system readjusts, temporarily making the lining more vulnerable to ulceration. If you’ve recently quit smoking and suddenly find yourself dealing with canker sores for the first time, this is almost certainly the reason, and the outbreaks typically stop on their own within a month. It’s worth knowing about because unexpected mouth sores right after quitting can feel like a reason to start smoking again, when in reality they’re a temporary side effect of your body returning to normal.