Canker Sore Remedies: How to Get Rid of Them Fast

Editorially reviewed by the Dental.me Editorial Team · Updated July 2026

A canker sore can turn a simple sip of coffee or bite of a sandwich into a sharp jolt of pain. These small mouth ulcers are extremely common, usually harmless, and almost always heal on their own. Still, the days spent waiting can be miserable, so it helps to know which canker sore remedies actually ease the sting and which ones are wishful thinking. This guide walks through what canker sores are, what sets them off, the treatments worth trying, and the warning signs that mean it is time to call your dentist.

What Is a Canker Sore?

A canker sore, known medically as an aphthous ulcer, is a small, shallow lesion that forms on the soft tissues inside your mouth. You will typically find them on the inside of the lips or cheeks, at the base of the gums, or under the tongue. They usually start as a tingling or burning spot and develop into a round or oval ulcer with a white or yellowish center and a red border.

Two points are worth repeating because they are so often misunderstood. First, canker sores are not contagious. You cannot catch one from someone else or pass yours along. Second, they are not the same thing as cold sores. Cold sores are caused by the herpes simplex virus, are contagious, and usually appear on or around the lips on the outside of the mouth. Canker sores stay inside. If you are unsure which one you are dealing with, our guide on canker sores versus cold sores breaks down the differences in detail.

What Triggers a Canker Sore?

There is rarely a single cause. Canker sores tend to appear when several small factors line up. Common triggers include:

• Minor mouth injury, such as biting your cheek, a hard toothbrush, a poking braces wire, or a sharp piece of food
• Acidic or spicy foods like citrus, tomatoes, coffee, and hot sauces
• Emotional stress and lack of sleep
• Hormonal changes, which is why some people notice a pattern around their menstrual cycle
• Sodium lauryl sulfate (SLS), a foaming agent in many toothpastes that irritates some people’s mouths
• Food sensitivities, sometimes to chocolate, nuts, cheese, or gluten
• Nutritional gaps, particularly low vitamin B12, iron, folate, or zinc

Because triggers vary so much from person to person, keeping a simple note of when your sores appear and what you ate or experienced beforehand is one of the most useful things you can do. Over a few weeks a pattern often emerges, and once you can see your own triggers you can start to head sores off before they form rather than only treating them afterward.

How to Get Rid of Canker Sores Fast

Most canker sores heal on their own within one to two weeks, so the real goal of any remedy is to dull the pain and protect the ulcer while your body does the repair work. There is no treatment that will erase a sore instantly, and anyone promising an overnight cure is overselling it. What you can realistically do is take the sting out, stop the ulcer from being reinjured, and keep the area clean so healing is not delayed. These are the approaches most likely to help.

Rinses that soothe and clean

A warm salt-water rinse (about half a teaspoon of salt in a cup of warm water) or a baking-soda rinse can reduce irritation and keep the area clean. Swish gently for 15 to 30 seconds and spit. A diluted hydrogen peroxide rinse (equal parts 3% peroxide and water) used sparingly can also help disinfect the area. An alcohol-free antimicrobial mouthwash is another option; if you are not sure which formula suits you, see our guide on how to choose a mouthwash.

Over-the-counter topical treatments

Pharmacy shelves carry several products aimed directly at mouth ulcers. Numbing gels containing benzocaine dull the pain for short stretches, which is helpful before meals. Protective pastes and patches form a barrier over the sore so food and teeth do not aggravate it. Dabbing a little milk of magnesia on the ulcer with a cotton swab can also coat and soothe the area.

Simple at-home comfort measures

• Let a small piece of ice melt against the sore to numb it and calm inflammation
• Avoid acidic, spicy, salty, and rough or crunchy foods until it heals
• Switch to an SLS-free toothpaste if you get sores often
• Brush gently with a soft-bristled brush to avoid reinjuring the tissue

None of these will make a sore vanish overnight, but together they take the edge off and remove the constant irritation that keeps an ulcer angry.

Prescription Options for Severe or Recurrent Sores

If your sores are unusually large, extremely painful, or keep coming back, a dentist or doctor has stronger tools. Prescription corticosteroid gels or pastes calm the inflammation more aggressively than anything over the counter. Prescription-strength antimicrobial or anti-inflammatory rinses can help when sores are numerous or hard to reach. In some cases a dentist may use a cautery or a topical treatment that chemically seals the ulcer to cut down healing time and pain. For people with frequent outbreaks, a provider may also look into an underlying cause, such as a nutritional deficiency, and treat that directly. Persistent or severe mouth pain is not something you have to simply endure, and it is worth understanding what counts as a dental emergency so you know when prompt care is warranted.

What Does Not Help, and What to Avoid

Plenty of home tricks circulate online, and some do more harm than good. Applying undiluted hydrogen peroxide, rubbing alcohol, or full-strength essential oils onto an open sore can burn the tissue and slow healing. Aspirin held directly against the gums is an old remedy that can cause a chemical burn rather than relief. There is no reliable evidence that a canker sore needs to be dried out, cauterized at home, or scrubbed; irritating it only prolongs the pain. Continuing to eat citrus, hot sauces, and salty snacks while a sore is active will also keep it flared up. And because canker sores are not caused by bacteria the way a cavity is, antibiotics are not an appropriate treatment for a routine ulcer.

How to Prevent Canker Sores

You cannot always stop a canker sore from forming, but you can reduce how often they appear:

• Brush gently and floss carefully to avoid nicking the soft tissue
• Choose an SLS-free toothpaste if you are prone to ulcers
• Manage stress and protect your sleep, since fatigue is a common trigger
• Identify and limit your personal food triggers
• Eat a balanced diet and talk to your doctor about testing for B12, iron, folate, or zinc deficiency if sores are frequent
• Fix rough teeth, sharp fillings, or poorly fitting appliances that keep injuring the same spot

Good daily oral care has a bonus benefit beyond fewer sores: a cleaner, healthier mouth. If you struggle with related issues, our article on what causes bad breath covers habits that support overall mouth health.

When to See a Dentist or Doctor

Most canker sores are a nuisance rather than a medical problem, but a few situations deserve professional attention. Make an appointment if a sore is:

• Larger than about a centimeter across
• Still present after roughly three weeks
• Recurring very frequently, or appearing in clusters that never fully clear
• Accompanied by a fever, difficulty swallowing, or feeling generally unwell
• Unusually placed, spreading, or not healing the way past sores did

A sore that does not follow the usual pattern should be examined so a dentist or doctor can rule out other conditions. The vast majority of the time, though, a canker sore is simply your mouth’s way of reacting to a small insult, and a mix of gentle rinses, protective gels, and trigger avoidance will carry you comfortably through to healing. Be patient with it, keep it clean, and it will almost always take care of itself.

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