How to make a canker sore stop hurting

Canker Sore (Aphthous Ulcer)

Written by WebMD Editorial Contributors

Medically Reviewed by Sabrina Felson, MD on May 12, 2021

In this Article

  • What Is a Canker Sore?
  • Canker Sore Causes and Risk Factors
  • Canker Sore vs. Cold Sore
  • Canker Sore Symptoms
  • Canker Sore Diagnosis
  • Canker Sore Treatment
  • Canker Sore Home Remedies
  • Canker Sore Prevention

What Is a Canker Sore?

A canker sore is a small, shallow open wound (or ulcer) in your mouth that can make eating and talking uncomfortable. They’re also known as aphthous ulcers. There are a few types of canker sores:

  • Minor canker sores. These may show up three or four times a year. They typically happen in people ages 10 to 20. They’re less than 1 centimeter across and heal in about a week with no scarring.
  • Major canker sores. These are less common. The ulcers are bigger and can last more than 2 weeks. They often heal with scarring.
  • Herpetiform canker sores. These are rare and show up as clusters of tiny ulcers. They usually heal in about a week.

 

Canker Sore Causes and Risk Factors

Doctors don’t know what exactly causes most canker sores. 

Things that might cause minor sores include:

  • Stress 
  • Tissue injury, like from a sharp tooth or a dental appliance
  • Certain foods, including citrus or acidic fruits and vegetables (such as lemons, oranges, pineapples, apples, figs, tomatoes, and strawberries)
  • Nonsteroidal anti-inflammatory drugs like ibuprofen
  • An allergy to something in your food or in your toothpaste or mouthwash
  • Helicobacter pylori, the bacteria that can cause peptic ulcers

Things that might cause complex canker sores include:

  • An underlying health condition like a weakened immune system, HIV/AIDS, lupus, or Behcet’s disease
  • Nutritional problems like too little vitamin B12, zinc, folic acid, or iron
  • Gastrointestinal diseases like celiac or Crohn’s

About 1 in 5 people gets canker sores regularly. They’re more common in women, possibly because of hormonal differences. They may also run in families.

Canker Sore vs. Cold Sore

Canker and cold sores aren’t the same. 

Cold sores, also called fever blisters or herpes simplex type 1, are groups of painful, fluid-filled blisters. Unlike canker sores, a virus causes cold sores, and they’re highly contagious. Also, cold sores typically appear outside your mouth -- usually under your nose, around your lips, or under your chin -- but canker sores show up inside your mouth.

Canker Sore Symptoms

You may have a canker sore if you have:

  • A tingling or burning sensation, often 6 to 24 hours before a canker sore
  • Small sores in your mouth that are round or oval, white, gray, or pale yellow with a red edge or border
  • A painful sore or sores that appear alone or in clusters inside your mouth: on your tongue, at the base of the gums, on your soft palate (the back portion of the roof of your mouth), or inside your cheeks

Severe canker sore attacks may also cause:

  • Fever
  • Fatigue
  • Swollen lymph nodes

Canker Sore Diagnosis

 

Canker sores usually aren’t serious. Call your dentist if you have:

  • Unusually large sores
  • Sores that spread
  • Sores that last 3 weeks or longer
  • Extreme pain despite avoiding trigger foods and taking over-the-counter pain medication
  • Trouble drinking enough fluids
  • A high fever with canker sores
  • Frequent or lasting mouth sores, which may be a sign of an underlying problem, such as a serious skin disorder called pemphigus, celiac disease, inflammatory bowel disease, Behcet's disease, autoimmune disease, anemia, HIV, or, in rare cases, oral cancer or leukemia

They can usually make a diagnosis based on a physical exam and your medical history. They might want to test your blood to see whether a vitamin deficiency or another health condition is causing the sores.

Canker Sore Treatment

Pain from a canker sore tends to get better in a few days, and the sores usually heal without treatment in about a week or two. Treatment for large, long-lasting, or unusually painful sores might include:

  • Mouthwashes. Your doctor can prescribe a rinse that has a steroid or a painkiller.
  • Topical medications. Your doctor may prescribe a topical medication containing a steroid for the inflammation, and a topical analgesic like lidocaine to relieve pain. Aphthasol, a prescription ointment described as an "oral paste," may reduce pain and healing time.
  • Oral medications. The ulcer drug sucralfate (Carafate) and the gout drug colchicine (Mitigare) can also treat canker sores. Or your doctor might give you steroid pills.
  • Nutritional supplements. You might need these if a nutrient deficiency is causing your canker sores.   
  • Cautery. Dental lasers can help you feel better right away. Your doctor can also cauterize sores with chemicals like debacterol or silver nitrate.

Canker Sore Home Remedies

Home treatments to speed healing and help you feel better include:

  • Topical products. Medicated gels, creams, pastes, and liquids go on the sore.
  • Mouth rinses. Mix salt or baking soda in warm water, and swish it around your mouth.
  • Milk of magnesia. Put a bit on a cotton swab, and dab it on the sore.

Canker Sore Prevention

There’s no cure for canker sores, and they often come back. But you might get them less often if you:

What kills canker sores fast?

Get Rid of Canker Sores Quickly.
DIY mouth rinse. If you can reduce the acidity levels in your mouth, you can speed up healing time. ... .
2 Milk of magnesia. Milk of magnesia works just like salt to eliminate acids in the mouth. ... .
Ice. ... .
Medicated mouthwash. ... .
Aloe vera. ... .
Hydrogen peroxide. ... .
Topical products..

Why is my canker sore so painful?

It can make you wonder, why do canker sores hurt at all? A canker sore is essentially an injury to the tissue inside your mouth. The digestive enzymes and acids in your mouth then constantly flow over this open wound, causing the pain you feel. It's similar to spilling salt into a paper cut, but over and over.

How long does it take for a canker sore to stop hurting?

The pain from your canker sore should decrease in 7 to 10 days, and it should heal completely in 1 to 3 weeks. In most cases, a canker sore will go away by itself. Home treatment can ease pain and discomfort.

How do you numb a canker sore?

Topical numbing medications: Benzocaine and lidocaine are numbing medications that come as a gel or liquid. You can apply them directly to your canker sore and they will numb the area and provide pain relief. Both of these medications are available OTC at pharmacies.