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Updated on May 19, 2023
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Can You Pop a Canker Sore?

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Canker sores are otherwise known as aphthous ulcers. They are painful, exposed, shallow, open wounds that develop in the mouth.

You should never try to pop a canker sore. 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. 

What Causes Canker Sores?

While anyone can develop a canker sore, women are more susceptible than men. Aphthous ulcers may also run in families.

It’s possible to have more than one canker sore at a time. They may grow larger or spread in the mouth. Canker sores usually develop on the inside of the cheeks and lips, and tongue.

Canker sores are not cancerous and aren’t the same as cold sores or fever blisters.

Mouth sores develop for various reasons. These include:

  • Genetics
  • Damage to the lining inside the mouth, such as accidentally biting your cheek or tongue
  • Stress and anxiety
  • Hormonal changes
  • Eating spicy foods
  • Eating acidic foods and drinks, such as orange juice and citrus fruits
  • Stopping smoking
  • Having certain medical conditions, such as Behçet’s disease and viral infections
  • Taking specific medications
  • A weakened or overactive immune system


Canker sores are open, painful sores in the mouth caused by various genetic factors. They appear as circular lesions and often cause a tingling or burning sensation in the mouth. If you have canker sores that make you feel sluggish, along with a fever and swollen lymph nodes, seek medical attention immediately.

What's Inside a Canker Sore?

Sometimes canker sores are confused with boils.

While the two can sometimes appear similar, they are different.

Boils develop from infections that form in the oil glands or hair follicles on the skin. Often boils start as a sensitive area of the skin that eventually firms. A boil usually contains a pus-filled center that oozes. 

A canker sore is a flat ulcer that has lost the outer coating of tissue. It is not a fluid-filled lump or bump. It may be white, yellow, or gray with a red border. In some cases, a canker sore may ooze with pus. If this happens, the canker sore is likely infected.

When canker sores develop, your mouth may tingle before they appear. Shortly after, a small red bump forms. After a day or so, the bump bursts. A shallow white or yellow open wound is left with a red border.


Canker sores differ from boils because boils are filled with pus, while canker sores are not. Boils appear as bumps, and canker sores look flat.

Are Canker Sores Contagious?

Canker sores aren't contagious. Unlike cold sores, you don't get canker sores from kissing someone who has them. 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

Best Ways to Heal a Canker Sore

Several prescription treatments and home remedies speed up the healing process of mouth sores. However, it’s unlikely that any remedy or medication will cure a canker sore overnight.

Prescription treatments and home remedies for canker sores include:

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.

Topical Products

Topical over-the-counter and prescription items may help reduce pain and speed healing when applied to individual canker sores. Topical products for mouth sores often include ingredients like benzocaine, fluocinonide, or hydrogen peroxide.

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.

Some popular home remedies are:

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.


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. Remember to use unfiltered honey since it's less processed.

Warm Salt Water Rinse

Although they can be 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 around 30 seconds, then spit it out.

Hydrogen Peroxide and Water Rinse

Hydrogen peroxide can help reduce the bacteria present in a canker sore. To make this remedy at home, mix equal parts of hydrogen peroxide and water. Dab the solution onto the canker sore using a cotton swab.

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.

Many home remedies to treat canker sores aren’t well-researched or studied, so approach them cautiously. 

Do I Need to Visit the Doctor for a Canker Sore?

Most canker sores aren’t severe or a cause for concern. Mouth sores rarely prompt any side effects. However, some canker sores may require advice or attention from a doctor.

Speak to your doctor or a healthcare professional if you experience any of the following:

  • Pus drainage
  • Crusting
  • Increased redness
  • Swelling
  • Warmth
  • A sore bigger than usual
  • Multiple mouth ulcers
  • New sores developing before old ones heal
  • Canker sores that don’t heal after two weeks
  • Mouth ulcers that spread to the lips
  • Significantly painful sores
  • Difficulty eating or drinking
  • Fever


There is no overnight cure for canker sores. However, there are home remedies and OTC treatments for them. Canker sores usually resolve after a few days with proper treatment. If you're experiencing symptoms that are out of the ordinary, get in touch with your doctor.

Last updated on May 19, 2023
6 Sources Cited
Last updated on May 19, 2023
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. Canker sore: Care instructions,” My Health Alberta, 2019.
  2. Mouth sores,” MedlinePlus, 2020.
  3. Canker sore,” MedlinePlus, 2020.
  4. Mouth ulcers,” Nidirect Government Services. 
  5. Cold and Canker Sores,” University of Michigan.
  6. Fever Blisters & Canker Sores,” National Institute of Dental and Craniofacial Research.
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