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Canker Sores

Small, painful sores inside the mouth that aren’t contagious and usually heal on their own within a week or two. Knowing your triggers can mean fewer of them — and sores that keep coming back, or one that won’t heal, deserve a check with your dentist or doctor.

What are canker sores?

A canker sore is a painful, open sore inside the mouth. It is white or yellow in the middle with a bright red border, and it is not cancer (MedlinePlus). The medical name is aphthous ulcer, and when they keep coming back doctors call it recurrent aphthous stomatitis (Cleveland Clinic, Merck Manual). They can be quite painful, but they aren’t contagious (MedlinePlus). They usually show up on the soft, moving parts of the mouth: inside the lips and cheeks, on or under the tongue, and at the base of the gums (Cleveland Clinic, MedlinePlus). Many people feel burning or tingling a day or so before a sore appears (Cleveland Clinic, Merck Manual).

Three types

How common are they?

Very common. Recurrent canker sores are the most common condition of the lining of the mouth; a 2023 review puts the share of people affected at between 5% and 25%, peaking in the teens (review, Medicina Clínica). They are most common in teens and people in their 20s, and more common in women than men. It is unusual to get your first canker sore after age 40 (Cleveland Clinic). They can run in families (MedlinePlus). Some people get one or two sores a few times a year; others have almost constant outbreaks, and attacks usually ease with age (Merck Manual).

What causes them?

Nobody knows exactly. Experts think the immune system plays a part, genes may make some people more prone, and a range of things can set a sore off (Cleveland Clinic, American Dental Association). Common triggers include:

How long do they last?

The pain usually eases within a few days, and most sores heal within two weeks without any treatment (Cleveland Clinic). MedlinePlus says the pain often goes in 7 to 10 days and a sore can take 1 to 3 weeks to heal completely, with large ulcers taking longer (MedlinePlus). Major sores may take up to six weeks or more (American Academy of Family Physicians, Cleveland Clinic).

Canker sore or cold sore?

They are often confused, but they are different conditions (MedlinePlus, NHS):

When mouth ulcers keep coming back

Most canker sores are just canker sores. But frequent or unusual mouth ulcers can sometimes be a sign of something else, and the list of possible causes is long — from inherited fever syndromes to inflammatory bowel disease (review, Journal of Clinical and Aesthetic Dermatology). If your sores keep returning, a clinician may order tests, including blood tests, to look for a cause (MedlinePlus, Cleveland Clinic). Conditions linked to mouth ulcers include:

See a dentist or doctor if:

Side by side

Six approaches compared

For every condition we look at the same six approaches: what each involves, what it typically costs, and what a patient can realistically expect.

ApproachWhat it involves Estimated costWhat to expect
Conventional medicine (AMA) Over-the-counter numbing gels, protective patches and pastes, and alcohol-free or antiseptic rinses; prescription steroid or chlorhexidine rinses and ointments; tests for an underlying cause when sores keep returning; laser or cautery for severe sores. At one pharmacy: a mouth-sore pain-relief gel about $6, a canker-sore patch pack about $10, a mouth-sore rinse about $12. Dental or doctor visit: cost estimate being researched. Treatment eases pain and may speed healing; most sores heal within two weeks either way. No benzocaine products for children under 2. Frequent sores deserve a look for a cause.
Chiropractic Being researched — coming soon.
Acupuncture Being researched — coming soon.
Herbal medicine Licorice (including dissolving patches and rinses), aloe vera gel, honey and chamomile applied in the mouth. At one pharmacy: an aloe-containing canker gel about $5. Small studies suggest licorice and aloe may ease pain or shrink sores; evidence for honey and chamomile is mixed. Licorice can interact with steroids. Never give honey to a baby under 1.
Massage therapy Being researched — coming soon.
MBHA Wellness Coach A soft toothbrush and gentle brushing, an SLS-free toothpaste trial, a trigger-food and stress diary, salt-water rinses, iron-, folate- and B12-rich meals, and tracking outbreaks to share with your clinician. Cost estimate being researched. Knowing your triggers may mean fewer and milder sores. A coach supports you; a coach never replaces a check for sores that won’t heal or keep coming back.

Approach 1 of 6

Conventional medicine (AMA)

Most canker sores go away without treatment (MedlinePlus). The aim of treatment is to ease the pain while the sore heals, help it heal a little faster where possible, and look for a cause when sores keep coming back (American Academy of Family Physicians, Cleveland Clinic).

1. Over-the-counter relief

Benzocaine and young children. The FDA says over-the-counter mouth products containing benzocaine should not be used in children under 2 years old, under any circumstances, and should not be used for teething. Benzocaine can cause methemoglobinemia, a serious and sometimes fatal condition in which the blood carries much less oxygen. It can happen after a single use, even in someone who has used benzocaine before without trouble (FDA, FDA). Get medical help right away if anyone — child or adult — develops pale, gray or blue skin, shortness of breath, tiredness, headache, light-headedness or a racing heart after using it (FDA).

2. Prescription treatment

For severe or frequent sores, a dentist or doctor may prescribe (MedlinePlus, Cleveland Clinic, Merck Manual):

3. Looking for a cause

If sores persist or keep returning, a clinician may check for other causes, sometimes with blood tests or a small sample (biopsy) of the sore (MedlinePlus, American Academy of Family Physicians). If a test shows low iron, folate or vitamin B12, treating that deficiency is part of the plan (Cleveland Clinic); your provider will usually measure your iron level before you start iron pills (MedlinePlus). If another condition is behind the sores, treating it can help (MedlinePlus).

Who to see

Your dentist or primary care provider is a good first stop: most of the time they can tell what a mouth ulcer is by looking at it (MedlinePlus). Your dental team also checks for signs of mouth cancer at each visit (American Dental Association).

What it costs

How well it works — what to expect

Expect relief rather than a quick fix: canker sores almost always heal on their own, with pain easing in a few days (MedlinePlus), and treatment can speed this up or ease symptoms (American Academy of Family Physicians). A 2026 review of 41 earlier reviews found that steroids applied to the sore and low-level laser therapy consistently reduced pain and shortened healing time, but evidence that any treatment prevents sores from coming back is limited (umbrella review, Journal of Dermatological Treatment). There is no cure for recurring canker sores (American Academy of Family Physicians).

Find a medical doctor in our directory

Approach 4 of 6

Herbal medicine

Several plant-based remedies have been tested on canker sores, mostly in small studies. They are worth discussing with your dentist or pharmacist, but none replaces a check-up when the warning signs above apply.

Licorice root

The U.S. National Center for Complementary and Integrative Health (NCCIH) says a licorice mouth rinse or gargle might reduce ulcer size and pain in people with recurring canker sores, while licorice applied to the sore might reduce ulcer size only — though overall there isn’t enough high-quality evidence to clearly support licorice for any condition (NCCIH).

  • In a 2008 U.S. trial, sores treated with a dissolving oral patch containing licorice root extract had shrunk significantly by day 8, while untreated sores had grown slightly. By day 4, 81% of the licorice-patch group reported no pain at rest, compared with 63% of the dummy-patch group and 40% of the untreated group. Each group had 23 people (trial, General Dentistry).
  • A 2023 review found six trials (314 people) of licorice pastes, patches and mouthwashes. The authors reported less pain, smaller sores and faster healing with no side effects, but the studies were too different to combine statistically (systematic review, Iranian Journal of Medical Sciences).

Safety: licorice contains glycyrrhizin, which can cause serious side effects, including irregular heartbeat, especially in large amounts or over a long time, and even small amounts have caused problems in people with high blood pressure or heart or kidney disease. “DGL” (deglycyrrhizinated licorice) products have the glycyrrhizin removed. Licorice applied to the skin may irritate, and licorice can interact with corticosteroids — worth knowing, since steroids are a common prescription for canker sores. Large amounts are unsafe in pregnancy (NCCIH).

Aloe vera

In a 2022 trial of 60 people aged 15 to 25 in Syria, an aloe vera gel shrank minor canker sores and eased pain more than a dummy gel by day 5, and did better than amlexanox, a medicated paste (trial, Cureus). That is a single small study. Aloe gel on the skin is generally well tolerated, with occasional burning, itching or rash; aloe taken by mouth is a different matter, with possible side effects, a possible interaction with the heart medicine digoxin, and safety concerns in pregnancy and breastfeeding (NCCIH).

Honey

A 2025 trial of 30 people in Egypt found that thyme honey on minor canker sores eased pain and shrank sores more than a standard steroid paste (trial, European Journal of Oral Sciences). A 2025 review that pooled trials found mixed results for honey compared with the steroid, and warned that there were few placebo-controlled trials and that the studies were at moderate to high risk of bias (systematic review, BMC Oral Health). Never give honey to a baby under 1 year old — it can carry the spores that cause infant botulism (MedlinePlus).

Chamomile

In a small 2006 study, most people using a chamomile extract on canker sores and other painful mouth ulcers rated its pain relief as excellent (study, Journal of Drugs in Dermatology). In a 2023 analysis of 43 trials of treatments applied to the sore, no treatment — chamomile included — clearly beat a placebo for pain, although chamomile ranked among the more promising (network meta-analysis, Journal of Oral Pathology and Medicine), and a 2025 review found chamomile did less well than a steroid paste (systematic review, BMC Oral Health). Chamomile can cause allergic reactions, more likely if you’re allergic to ragweed, chrysanthemums, marigolds or daisies, and it may interact with warfarin, some other medicines and birth control pills (NCCIH, NCCIH).

The bottom line

A 2026 review of the research found that herbal agents showed favorable short-term results with good safety (umbrella review, Journal of Dermatological Treatment), but most herbal studies are small. Tell your dentist, doctor and pharmacist about every herb or supplement you use, because some herbs and medicines interact in harmful ways (NCCIH). We don’t list strengths or doses here.

What it costs

GUM Canker-X gel, which contains aloe vera and coats the sore: about $5 (retail listing: Pasteur Pharmacy). Other herbal products: cost estimate being researched.

Approach 6 of 6

MBHA Wellness Coach

There is no sure way to prevent canker sores, but noticing and avoiding your own triggers helps many people (Cleveland Clinic). An MBHA Wellness Coach can help you find yours and build gentler habits — alongside, never instead of, your dentist or doctor.

Gentle mouth care

Try an SLS-free toothpaste

Cleveland Clinic and the NHS suggest a toothpaste without sodium lauryl sulfate (Cleveland Clinic, NHS). The evidence is encouraging but limited: a 2019 review of four small crossover trials (124 people) found that SLS-free toothpaste reduced the number of ulcers, how long they lasted, how often they came and how much they hurt, while calling for better trials (systematic review, Journal of Oral Pathology and Medicine, commentary, Journal of Evidence-Based Dental Practice). Check the ingredient list, or ask your dentist to recommend a brand (Cleveland Clinic). A coach can help you run a fair trial: switch toothpaste and track whether your sores change.

Food and drink

Eating for iron, folate and vitamin B12

A healthy, balanced diet is part of the NHS self-care advice (NHS). If you get sores often, ask your provider whether a blood test for deficiencies makes sense before taking supplements (Cleveland Clinic). Good food sources include:

  • Vitamin B12: fish, meat, poultry, eggs, milk and dairy foods, and some fortified breakfast cereals and nutritional yeasts. B12 isn’t found in plant foods unless they are fortified, so vegetarians and vegans need to plan for it (MedlinePlus). Weight-loss surgery, celiac disease, Crohn’s, long-term use of heartburn medicines or metformin can also lower B12 (MedlinePlus).
  • Folate: dark green leafy vegetables, dried beans and peas, citrus fruits, and fortified breads, cereals and pastas (MedlinePlus).
  • Iron: meat, poultry, fish, lentils, beans, chickpeas, whole-grain bread, oatmeal and leafy greens. Vitamin C foods such as oranges, strawberries, broccoli and tomatoes help your body absorb iron (MedlinePlus).

Stress and rest

Stress and tiredness are common triggers (NHS, Merck Manual). Cleveland Clinic suggests stress-reduction techniques such as mindfulness and meditation (Cleveland Clinic). A coach can help you build a routine you’ll keep — especially around exams, deadlines or other busy times.

Track your outbreaks

Note when each sore appears, how big it is, how long it lasts, and what was going on — foods, stress, your menstrual cycle, a bitten cheek, a new medicine. Bring the log to your dentist or doctor: getting sores more than 2 or 3 times a year, or sores that come with other symptoms, is a reason to look for a cause (MedlinePlus).

Still being researched: Chiropractic, Acupuncture, Massage therapy. We add each approach once its costs and results are sourced. Are you a practitioner with experience treating Canker Sores? Tell us.

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Sources

This page is for education only and is not medical advice. Costs are typical U.S. ranges and estimates; yours will depend on your provider, location and insurance. Talk with your doctor before starting, stopping or combining any treatment. In an emergency, call 911. See our disclaimer.

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