How long do canker sores last?

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 up the healing process, but they’re not a magical cure. It’s unlikely any remedy will cure a canker sore overnight.

Many remedies for canker sores aren’t well-studied, so use with caution. You can also call your doctor’s office if you have questions.

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 a mouthwash that contains alcohol because it can irritate the sore.

You can find an OTC mouthwash intended for mouth sores that has a mixture containing lidocaine, an ingredient that can help alleviate canker sore pain. A doctor may also prescribe you a prescription mouthwash containing dexamethasone or lidocaine.

Aside from mouthwashes, there are several other treatments for canker sores that you can buy over the counter. These include anesthetics in gel or cream form that contain lidocaine to help with pain and inflammation.

A corticosteroid can also be purchased. This type of product may help with pain and healing.

Nonsteroidal anti-inflammatory drugs (NSAIDs) that contain diclofenac are another helpful anti-inflammatory option for pain relief.

People who are pregnant or breastfeeding should exercise caution before trying an OTC treatment. Be sure to check with a doctor to see if these options are safe for you.

In addition to mouth rinses and OTC and prescription products, canker sores can be addressed with various home remedies.

Here are 16 homemade remedies to consider.

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.

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 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 a painful one, for mouth sores of any kind. It may help dry out canker sores.

To use:

  1. Dissolve 1 teaspoon (tsp.) of 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

Baking soda is thought to restore pH balance and reduce inflammation, which may help heal canker sores.

To use:

  1. Dissolve 1 tsp. of 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 or inflammatory bowel disease (IBD).

A 2020 study done 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. More research on humans is needed.

To aid in preventing or treating a canker sore, eat at least 1 cup of yogurt each day.

5. Honey

Honey is known for its antibacterial and anti-inflammatory abilities. According to a 2014 study, honey is effective in reducing canker sore pain, size, and redness. It also may help prevent secondary infection.

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

All honey isn’t created equal. 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 its healing properties.

6. Coconut oil

Research has shown 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. It tastes great too!

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, and then spit it out.

8. Milk of magnesia

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

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 applying it. You can also rinse your mouth with freshly brewed chamomile tea. Repeat the treatment 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. of 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 also be beneficial. Repeat either treatment up to three times daily.

11. Sage

Sage tea has traditionally been used 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 is made from deglycyrrhizinated licorice (DGL), an herbal licorice extract. It’s thought to have anti-inflammatory abilities and is considered a natural remedy for stomach ulcers. DGL is available in supplement form, which you can use to make a 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. If you think the patch is a good option for you, talk with a doctor or dentist about where to purchase it.

13. Apple cider vinegar mouthwash

Apple cider vinegar (ACV) is touted as a cure for almost everything, including canker sores. It’s thought that the acid in ACV helps kill bacteria that irritate the sore. The treatment is controversial, however, because acidic foods can cause or worsen canker sores in some people. Use it with caution.

To use:

  1. Combine 1 tsp. of 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 weak, canker sores may thrive. Zinc is a mineral that boosts your immunity. Taking zinc lozenges may help your immune system fight off bacteria that cause canker sores. It may also speed up healing time if you have a sore.

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.

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 with a doctor before use.

16. Watermelon frost

Watermelon frost has been considered an effective remedy for canker sores in traditional Chinese medicine. Studies have shown its effectiveness in treating canker sores.

It’s sold 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 try making 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.

Talk with a doctor 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.

You should contact a doctor or dentist if your canker sore is caused by a jagged or sharp tooth or a dental hygiene tool.