Canker sores typically heal on their own with time. But over-the-counter products, including mouth rinses and topical gels, may relieve pain and help them go away faster.

This article takes a look at how long canker sores last, what’s the best (and fastest) way to heal them, and when to seek medical help.

Canker sores (aphthous ulcers) occur inside your mouth or on your gums. Although they can be painful and make it difficult to talk or eat, they usually don’t cause lasting damage. Most canker sores heal on their own within a couple of weeks.

Several home remedies or over-the-counter (OTC) products can help speed the healing process, but it’s unlikely any remedy will cure a canker sore overnight.

Many home remedies for canker sores aren’t well-studied, so use them cautiously. You can also contact a doctor or dentist’s office if you have questions.

Several OTC treatments may help heal canker sores. These include:

If you are pregnant or breastfeeding, consider talking with a doctor to see if these options are safe for you before using them.

Mouth rinses for canker sores

A regular mouthwash containing chlorhexidine can help prevent germs from spreading and worsening the canker sore. It can also help avoid further inflammation. However, you’ll want to avoid mouthwash that contains alcohol because it can irritate the sore.

OTC mouthwashes intended for mouth sores typically contain lidocaine, an ingredient that can help relieve canker sore pain. A doctor may also prescribe a prescription mouthwash containing dexamethasone or lidocaine.

In addition to mouth rinses and OTC and prescription products, some home remedies may help relieve canker sores.

1. Alum powder

Alum powder is made from potassium aluminum sulfate. It’s often used to preserve food and to pickle vegetables. Alum has astringent properties that may help shrink tissues and dry out canker sores, according to older research from 2016.

To use:

  1. Create a paste by mixing a tiny amount of alum powder with a drop of water.
  2. Dab the paste onto a canker sore.
  3. Leave it on for at least 1 minute.
  4. Rinse your mouth thoroughly.
  5. Repeat daily until your canker sore is gone.

2. Saltwater rinse

Rinsing your mouth with salt water is a go-to home remedy, although painful, for mouth sores of any kind. It may help dry out canker sores.

To use:

  1. Dissolve 1 teaspoon (tsp.) salt in 1/2 cup of warm water.
  2. Swirl this solution in your mouth for 15 to 30 seconds, then spit it out.
  3. Repeat every few hours as needed.

3. Baking soda rinse

Some people believe baking soda can restore pH balance and reduce inflammation. It may help heal canker sores.

To use:

  1. Dissolve 1 tsp. baking soda in 1/2 cup of water.
  2. Swirl this solution in your mouth for 15 to 30 seconds, then spit it out.
  3. Repeat every few hours as needed.

Baking soda won’t harm you if you swallow it, but it’s super salty, so try to avoid doing so.

4. Yogurt

The exact cause of canker sores is unknown. Some may be caused by Helicobacter pylori (H. pylori) bacteria, which causes stomach ulcers, or inflammatory bowel disease (IBD).

A 2020 study on mice showed that live probiotic cultures, such as Lactobacillus, may help eradicate H. pylori. In theory, if either of those conditions caused your canker sores, eating yogurt that contains live probiotic cultures may help. But more research on humans is needed.

To help prevent or treat a canker sore, eat at least 1 cup of yogurt daily.

5. Honey

Honey is known for its antibacterial and anti-inflammatory abilities. Research suggests that honey is effective in wound healing, which may include reducing canker sore pain, size, and redness. It also may help prevent secondary infection.

To use, apply honey to the sore four times daily.

Most honey found at a grocery store is pasteurized at high heat, which destroys most nutrients. Unpasteurized, unfiltered honey, like Manuka honey, is less processed and retains healing properties.

Do not give honey to infants under 12 months of age, as it can potentially cause infant botulism.

6. Coconut oil

Research from 2019 suggests that coconut oil has antimicrobial properties due to its high amount of lauric acid. It may help treat canker sores caused by bacteria and prevent them from spreading. Coconut oil is also a natural anti-inflammatory and may help reduce redness and pain.

To use, generously apply coconut oil to the sore. Reapply several times per day until your canker sore is gone.

7. Hydrogen peroxide

Hydrogen peroxide promotes the healing of a canker sore by cleaning the sore and reducing bacteria in your mouth.

To use:

  1. Dilute a 3 percent solution of hydrogen peroxide with equal parts water.
  2. Dip a cotton ball or cotton swab into the mixture.
  3. Apply the mixture directly to your canker sore a few times daily.

You can also use diluted hydrogen peroxide as a mouth rinse. Swish the rinse around your mouth for about a minute, then spit it out.

8. Milk of magnesia

Milk of magnesia contains magnesium hydroxide. It’s an acid neutralizer and laxative. When used orally, it may change the pH in your mouth, so the sore cannot thrive. It may also coat the sore to help prevent irritation and relieve pain.

There isn’t much research on the use of milk of magnesia for canker sores, but some people swear by it.

To use:

  1. Apply a small amount of milk of magnesia to your canker sore.
  2. Let it sit for several seconds, then rinse.
  3. Repeat up to three times daily.

9. Chamomile compress

Chamomile is used as a natural remedy to heal wounds and ease pain. German chamomile contains two compounds with anti-inflammatory and antiseptic abilities: azulene and levomenol. A chamomile tea bag can serve as a compress to soothe canker sores.

To use, apply a wet chamomile tea bag to your canker sore and leave it on for a few minutes. Make sure the tea bag isn’t too hot before using it. You can also rinse your mouth with freshly brewed and slightly cooled chamomile tea. Repeat three to four times daily.

10. Echinacea

Echinacea’s wound-healing and immune-boosting properties may help heal canker sores or prevent them from forming.

To use:

  1. Add about 1 tsp. liquid echinacea to equal parts warm water.
  2. Swish the solution around your mouth for about 2 minutes.
  3. Spit out or swallow the mixture.

Rinsing your mouth with echinacea tea may have similar effects. Repeat either treatment up to three times daily.

11. Sage

People have traditionally used sage tea to remedy mouth inflammation. Sage mouthwash works as a general mouth rinse for many oral problems. It has antibacterial, anti-inflammatory, antiseptic, and astringent properties. It may also help relieve pain.

You can find sage mouthwash in most pharmacies and use it as directed. Or, you can make your own sage rinse:

  1. Add boiling water to 1 to 2 tsp. of fresh sage leaves.
  2. Steep for at least 5 minutes.
  3. Strain and let the solution cool.
  4. Swish the rinse around your mouth for a couple of minutes.
  5. Swallow the rinse or spit it out.

12. DGL mouthwash

DGL mouthwash contains deglycyrrhizinated licorice (DGL), an herbal licorice extract. It may reduce pain and healing time in people with mouth ulcers, due to its anti-inflammatory abilities, according to 2022 research. Some people also use it as a natural remedy for stomach ulcers. DGL is available in supplement form, which you can use to make mouthwash.

To use:

  1. Mix the powder of one DGL capsule (200 milligrams) with 1 cup of warm water.
  2. Swish the solution around your mouth for about 3 minutes.
  3. Spit it out.

DGL is also available as a mouth patch to help shrink canker sores. You apply the patch to a sore and leave it in place for at least 30 minutes.

13. Apple cider vinegar mouthwash

Apple cider vinegar (ACV) is touted as a cure for almost everything, including canker sores. Because ACV has antibacterial properties, some people believe it may reduce bacteria in the mouth that may irritate the canker sore. But T]the treatment is controversial because acidic foods can cause or worsen canker sores in some people. Use it with caution.

To use:

  1. Combine 1 tsp. ACV and 1 cup of water.
  2. Swish this mixture around your mouth for 30 seconds to 1 minute.
  3. Spit it out, and rinse your mouth thoroughly.
  4. Repeat daily.

Many websites suggest applying ACV directly to the canker sore with a cotton swab. This approach may speed up healing time in some people, but for others, it could cause additional pain and irritation.

Either way, it’s important to rinse your mouth after using ACV to prevent damage to tooth enamel.

14. Zinc lozenges

If your immune system is weakened, canker sores may thrive. Zinc is a mineral that supports your immune function. Zinc lozenges may help your immune system fight off bacteria that cause canker sores. It may also speed up healing time.

Zinc lozenges are available online and at most pharmacies. They may contain other ingredients, such as echinacea. You usually dissolve one in your mouth. Check the manufacturer’s directions to see how often you should do so.

15. Vitamin B complex supplement

You may get canker sores more often if your diet is low in vitamin B12. It’s unclear exactly how vitamin B12 heals canker sores, however.

According to a 2009 study, participants taking 1,000 micrograms of vitamin B12 daily had fewer canker sore outbreaks, fewer sores overall, and less pain than those taking a placebo. More current research is still needed to validate this.

Other B vitamins may also help. A vitamin B complex supplement contains all eight B vitamins, including B12. Vitamin B complex supplements may cause side effects, so consult a doctor before use.

16. Watermelon frost

Traditional Chinese medicine suggests watermelon frost may treat canker sores. But more research on watermelon frost is still needed to determine if it is a safe and effective remedy.

You can find it as a:

  • powder
  • tablet
  • spray

Apply it directly to the sore for pain relief and quicker healing.

You can buy watermelon frost from an Asian herb store or online or make your own.

Most canker sores aren’t a cause for concern. They rarely leave behind lasting side effects. Still, some canker sores justify a call to a doctor or dentist.

Talk with a medical professional if you experience any of the following:

  • The sore is larger than 1-3 centimeters in size.
  • You have multiple sores.
  • New sores form before old ones have healed.
  • The sore doesn’t heal after 2 weeks.
  • The sore spreads to your lips.
  • The sore causes extreme pain.
  • The sore makes eating or drinking intolerable.
  • You also have a fever.

Consider contacting a doctor or dentist if your canker sore is caused by a jagged or sharp tooth or a dental hygiene tool.

How do you heal a canker sore fast overnight?

There is no overnight remedy for a canker sore. But using OTC treatments, including OTC products and home remedies like baking soda, may support healing and reduce pain.

What is a canker sore caused by?

You can develop canker sores from a mouth injury, like biting the inside of your cheek, a viral infection, stress, or another health condition, such as a food allergy. You may be more likely to develop them if you have certain vitamin deficiencies.

What is the best medicine for canker sores?

Canker sores can go away on their own, but OTC treatment options, including mouth rinses and lidocaine-containing gels may reduce pain and mouth bacteria and support recovery.

Does salt help canker sores?

Gargling with salt water may help dry out canker sores but is likely to cause pain. You can also gargle with an OTC mouthwash.

Canker sores usually go away on their own. But certain mouth rinses and topical gels may relieve pain and help them go away faster.

But if you have a large canker sore, multiple sores, sores that won’t go away, or are in extreme pain, it may be best to see a doctor.