Updated on February 22, 2024
5 min read

Can You Pop a Canker Sore?

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No, you should never try to pop a canker sore. It may cause more problems if you do.

Canker sores are aphthous ulcers. They are painful, shallow, open wounds that develop in the mouth. They are not blisters, boils, or pimples, so there is nothing to squeeze out. 

Although uncomfortable, canker sores are often harmless and clear up by themselves. They can usually be treated at home without visiting your dentist or doctor.

When to See a Doctor

Most canker sores aren’t severe or a cause for concern. They usually resolve on their own within 1 to 3 weeks.3

However, some canker sores may require advice or attention from a doctor. Speak to a healthcare professional if you experience any of the following:

  • Pus drainage
  • Increased redness and swelling
  • Significant pain
  • A sore bigger than usual
  • Multiple mouth ulcers
  • New sores develop before old ones heal
  • Canker sores that don’t heal after two weeks
  • Mouth ulcers that spread to the lips
  • Difficulty eating or drinking
  • Fever

Are Canker Sores Contagious?

No, canker sores aren’t contagious. Unlike cold sores, they don’t spread through kissing, sharing food, or saliva. 

Canker sores occur inside the mouth, while cold sores occur on the skin around the mouth. The herpes simplex virus (HSV) causes cold sores. HSV1 doesn’t cause canker sores.

However, canker sores can be painful and uncomfortable. You might want to avoid touching them or eating spicy food while they’re active.

Canker Sores

What Causes Canker Sores?

While their exact cause is unknown, canker sores may develop for various reasons, including stress, vitamin deficiencies, and lifestyle factors.1 They may also run in families.

Mouth sores have been associated with the following:

  • Genetics
  • Injury or damage to the inside of the mouth
  • Stress and anxiety
  • Hormonal changes
  • Eating spicy or acidic foods and beverages
  • Smoking or quitting smoking
  • Certain medical conditions, such as Behçet’s disease and viral infections
  • Specific medications
  • A weakened or overactive immune system
  • Deficiencies in folic acid, iron, or vitamin B12

Anyone can develop a canker sore, but women are more susceptible to them than men.2

What’s Inside a Canker Sore?

Unlike boils or cold sores, canker sores don’t contain any fluid. They first develop as a red bump that can burst after a day or so. After that, they appear as lesions with a white, yellow, or gray center and a red border. 

If you “pop” a canker sore, nothing will come out. Instead, you’re irritating an open wound and potentially worsening the situation.

In some cases, a canker sore may ooze with pus. If this happens, the canker sore is likely infected.

How to Prevent Canker Sores

If you’re prone to canker sores, you might develop them repeatedly. To prevent canker sores, try these tips:

  • Practice good oral hygiene – Brush twice and floss once daily, especially after meals. Use a soft brush, and don’t brush too hard.
  • Learn your triggers – Observe what may cause your canker sores, such as stressful situations or smoking. 
  • Monitor what you eat – Acidic or spicy foods may cause canker sores. If you experience this, avoid or cut back on trigger foods.
  • Manage stress – Learn stress reduction techniques if stress is a factor. 
7 ways to prevent canker sores

8 Best Ways to Heal a Canker Sore

You can’t cure a canker sore overnight; popping it won’t help it heal. However, some prescription treatments and home remedies can speed up the healing process of mouth sores:

1. Mouthwash Containing Dexamethasone

If you have several mouth sores, your doctor may prescribe a mouthwash containing the steroid dexamethasone. 

This mouth rinse helps reduce the pain and inflammation of mouth sores.

2. Topical Products

When applied to individual canker sores, over-the-counter and prescription topical items may help reduce pain and speed healing. 

Topical products for mouth sores often include ingredients like benzocaine, fluocinonide, or hydrogen peroxide.

3. Oral Medications

Oral medications may be prescribed when mouth ulcers are severe or do not respond to topical products. Ibuprofen may reduce pain from canker sores.

Oral steroid medications are also an option. However, they’re often prescribed as a last resort due to the possibility of severe side effects.

4. Chamomile Tea Compress

A chamomile tea compress can temporarily relieve discomfort associated with canker sores. 

Soak a tea bag in water and apply it to the painful areas. The tea will absorb into the canker sore and provide relief.

5. Honey

Honey is a natural sweetener that has anti-inflammatory properties. Applying honey to a canker sore can help to reduce the sore’s pain, size, and redness.

6. Warm Salt Water Rinse

Although painful, a warm salt water rinse can help dry a canker sore. 

Mix 1/2 cup of warm water with a teaspoon of salt. Dissolve the salt in the water, swish the mixture around your mouth for 30 seconds, then spit it out.

7. Hydrogen Peroxide and Water Rinse

Hydrogen peroxide can help reduce the bacteria present in a canker sore. 

Mix equal parts of hydrogen peroxide and water to make this remedy at home. Dab the solution onto the canker sore using a cotton swab.

8. Milk of Magnesia

Milk of magnesia neutralizes acid and coats the ulcer. This promotes healing and relieves burning sensations. 

You can dab some milk of magnesia onto a cotton swab and then apply it to the area. This method is recommended after a hydrogen peroxide and water rinse.


You should never pop a canker sore. Canker sources are ulcers that don’t contain fluid. Popping them could make it worse.

There is no overnight cure for canker sores. However, there are home remedies and OTC treatments for them. At home, you can soothe them with steroid mouthwashes, topical products, and saltwater rinses.

Canker sores usually resolve by themselves within a few days or weeks. If you’re experiencing symptoms that are out of the ordinary, contact your doctor.

Last updated on February 22, 2024
8 Sources Cited
Last updated on February 22, 2024
All NewMouth content is medically reviewed and fact-checked by a licensed dentist or orthodontist to ensure the information is factual, current, and relevant.

We have strict sourcing guidelines and only cite from current scientific research, such as scholarly articles, dentistry textbooks, government agencies, and medical journals. This also includes information provided by the American Dental Association (ADA), the American Association of Orthodontics (AAO), and the American Academy of Pediatrics (AAP).
  1. Fever Blisters & Canker Sores,” National Institute of Dental and Craniofacial Research, US Department of Health and Human Services, 2021.
  2. Canker sores (mouth ulcers): Overview.” InformedHealth.org, National Library of Medicine, 2019.
  3. Canker sore.” Mount Sinai, Icahn School of Medicine at Mount Sinai, 2023.
  4. Canker sore: Care instructions,” My Health Alberta, Government of Alberta, 2019.
  5. Mouth sores,” MedlinePlus, National Library of Medicine, 2020.
  6. Canker sore,” MedlinePlus, National Library of Medicine, 2020.
  7. Mouth ulcers,” Nidirect Government Services, 2023.
  8. Cold and Canker Sores,” University Health Service, University of Michigan, 2023.
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