Mouth Ulcer Treatment: How to Heal Canker Sores Fast and When to See a Doctor

That small, stinging spot inside your mouth turns every bite, sip, and word into a wince. You just want it gone. The good news: most mouth ulcers are harmless and heal on their own, and the right at-home care can make the days until then far more comfortable.

Here is what actually works for mouth ulcer treatment, what the evidence says about each option, and the signs that mean it is time to stop self-treating and see a clinician.

What is a mouth ulcer?

A mouth ulcer, also called a canker sore or aphthous ulcer, is a small, shallow sore on the soft tissues inside your mouth, such as the inner cheeks, lips, or under the tongue. They are not contagious and are different from cold sores, which appear on the lips and are caused by a virus.

Recurrent aphthous stomatitis (RAS), the medical term for sores that keep coming back, is one of the most common oral conditions, with reported prevalence between 5% and 25% of people. Ulcers are usually grouped into three types: minor, major, and herpetiform. Minor ulcers make up roughly 80 to 90 percent of cases and heal without scarring.

How long does a mouth ulcer last?

Most minor mouth ulcers are self-limiting and heal on their own within 1 to 2 weeks (about 7 to 14 days), typically without scarring. The goal of treatment during that window is not to force the sore to vanish overnight, but to ease the pain and help it heal a little faster.

If a sore is unusually large, severely painful, or has not healed after more than about 2 to 3 weeks, that is a reason to get it checked rather than wait it out.

How to treat a mouth ulcer and ease the pain

First-line mouth ulcer treatment is local and topical care in all cases. The aim is symptom relief, protecting the sore, and supporting healing. Helpful options include:

Topical corticosteroids are considered the mainstay of medical treatment. A clinician may recommend products such as triamcinolone acetonide, fluocinonide, clobetasol, or a dexamethasone rinse. These reduce pain and ulcer size and can speed healing, but an important caveat applies: they do not reduce how often ulcers come back.

• Protective barrier pastes that form a coating over the ulcer to shield it while it heals
• Topical local anaesthetics such as benzocaine or lidocaine for short-term pain relief
• Switching to a toothpaste free of sodium lauryl sulfate (SLS), which some people find gentler
• Avoiding acidic, spicy, salty, or rough foods that aggravate the sore
• Silver nitrate cauterisation, done by a clinician, to reduce pain in some cases

How to prevent mouth ulcers from coming back

Because topical steroids relieve symptoms but do not lower recurrence, prevention is about managing triggers. Common triggers include minor mouth trauma (like biting your cheek or eating rough foods), stress, hormonal fluctuations, acidic or spicy foods, and nutritional deficiencies such as vitamin B-12, zinc, folic acid, and iron.

A chlorhexidine mouth rinse may reduce how often ulcers recur, though it is not a first-line treatment. For people with frequent or severe outbreaks, a clinician may consider systemic therapy, but a 2012 Cochrane review of systemic treatments for recurrent aphthous stomatitis was inconclusive. Newer reviews suggest non-pharmacological approaches and laser therapy can offer a favorable risk-benefit profile. Identifying and addressing your personal triggers is often the most practical step.

When to see a doctor

Most mouth ulcers can be managed at home, but some warrant professional care. See a doctor or dentist if you notice any of the following.

Persistent or unusual sores deserve evaluation because they can occasionally point to an underlying issue beyond a routine canker sore.

• A sore that lasts longer than about 2 to 3 weeks or keeps growing
• An unusually large or extremely painful ulcer
• Sores that recur very frequently or are spreading
• Ulcers that make it hard to eat or drink, or come with a high fever
• Any sore where you are simply unsure what it is