Canker sores, also called aphthous ulcers, are small painful sores inside the mouth. The lesions are oval shaped ulcers with a yellow-gray center that a red ring surrounds. Canker sores typically last 1–2 weeks.
Canker sores can make eating, drinking, and talking painful. They usually go away without treatment within 2 weeks. Several over-the-counter (OTC) treatments are available to help speed up healing.
Canker sores are one of the most common medical conditions that affect the mucous membranes of the mouth. Most people get their first canker sore during their teenage years.
The exact cause of canker sores is unclear. However, they may have links to hormone changes, mouth injuries, and nutritional deficiencies.
In this article, we examine how long canker sores last. We also look at their healing timeline and the available treatments.
Canker sores are a common oral condition that affects about 20% of the population.
Although canker sores can occur on any mucous membrane in the body, the mouth is the most common site.
Canker sores typically form on the soft areas of the mouth. These areas include the:
- inside of the lip or cheek
- floor of the mouth
- soft palate
- back of the throat
A canker sore usually progresses from a sore spot into an ulcer over 1–3 days. The ulcer then enlarges to its final size over the next 3–4 days and stabilizes before it begins to heal.
In most individuals, canker sores resolve in 7–14 days.
The duration of a canker sore depends on its type. The different types are:
- Minor canker sores: These are the most common type of canker sores. They are up to 5 millimeters (mm) in diameter and last 7–14 days.
- Major canker sores: These are larger than 10 mm, and can extend to 3 centimeters. Major canker sores typically last for several weeks.
- Herpetiform canker sores: These are a much less common type of canker sore. They are the size of a pinpoint and often develop in clusters, which may join to form one large ulcer. Herpetiform canker sores can last for 1–2 weeks.
Canker sores usually heal without any treatment within a 2-week time frame.
The first stage of healing is the prodromal, or beginning stage, which is the period before the ulcer forms. An individual might feel a burning or prickling sensation that precedes a painful, raised reddened area on the mucous membrane.
In the next stage, the typical yellow-gray ulcer forms, with redness surrounding the ulcer like a halo. During this period, the pain may increase.
Finally, the healing stage begins, and healthy tissue starts closing over the sore. The pain goes away as the ulcer gets smaller.
The exact duration of each stage will vary among individuals, but the following timeline provides a guide of what to expect.
The prodromal stage, before the canker sore appears, lasts 1–3 days.
The ulcer has usually fully formed by about the third day. This stage tends to last 3–6 days, but in some cases, it can be longer.
The healing time frame of a canker sore depends on the type of lesion.
- Mild canker sores last between 7–14 days and should heal without scarring.
- Major canker sores can last for several weeks and be painful for longer. They often leave a scar in the mucous membrane.
- Herpetiform canker sores can last for 10–14 days and typically heal without scarring.
There is no cure for canker sores. Treatments and strategies that may lessen the pain and promote healing include:
- applying topical OTC protective gels or patches to form a barrier around the ulcer
- applying an OTC benzocaine pain liquid
- gargling with a homemade mouth rinse comprising 1 teaspoon of salt or baking soda in 1 cup of warm water
- using a cotton tipped swab to apply a small amount of sesame oil to the ulcer four times a day for 5 days
- taking ibuprofen to reduce inflammation and ease pain
- avoiding common canker sore irritants, such as hard, spicy, or citrus foods that could irritate the ulcer
- drinking cold fluids with a straw, eating Popsicles, or applying a small piece of ice to the sore for a short time to help numb the pain
- avoiding chewing gum
- keeping the mouth clean by brushing at least twice daily with a soft toothbrush
- correcting any vitamin deficiencies, such as folate and vitamin B-12 deficiencies
- practicing stress management techniques
A person should see a doctor or dentist if the canker sore:
- is unusually large or painful
- has not healed after 2 weeks
- occurs with other symptoms
- affects the ability to eat or drink
A doctor may suggest treatments such as:
- applying a prescription corticosteroid directly to the sore
- taking oral corticosteroids
- using a mouthwash three or four times a day that comprises equal parts lidocaine, diphenhydramine, and a liquid antacid to help reduce pain
- using chlorhexidine or corticosteroid mouth rinses
- applying OTC topical products containing benzocaine (e.g., Anbusol or Orajel)
Certain underlying medical problems can sometimes be associated with recurring canker sores. These include:
- Crohn’s disease
- celiac disease
- Behcet’s disease
A doctor may order additional tests if a person with canker sores has additional symptoms, such as a rash, stomach pain, or swollen lymph glands.
They may recommend a biopsy for oral ulcers lasting longer than 3–4 weeks.
Canker sores are a common type of mouth ulcer that typically lasts 1–2 weeks. They usually occur for the first time during a person’s teenage years.
People can treat canker sores with OTC pain-relieving gels, saltwater rinses, and prescription medications.
Although they are painful, canker sores are rarely severe, and they tend to go away on their own.
A person should see a doctor for canker sores that last longer than 2 weeks or are unusually large and painful.