A canker sore in the throat can be painful. However, home remedies, such as sucking an ice cube or using a saltwater gargle, may provide relief.

Also known as mouth ulcers or aphthous ulcers, canker sores are small lesions that develop in the mouth or throat. They can appear on the inside of the cheeks or lips, but they can sometimes affect the back of the throat and tonsils.

Read on to learn about what can cause a canker sore in the throat. This article also looks at treatment options, how doctors diagnose canker sores, and more.

View the slideshow below for photos of canker sores in the throat.

Canker sores affect the mucous membrane, the soft protective layer lining the throat and mouth. They may look like a small gray or white spot with a red border. They may appear slightly sunken, with raised edges.

Most canker sores are only a few millimeters wide.

Pain is the main symptom of a canker sore. A person may feel a tingling or burning sensation in the affected area.

Eating spicy or acidic foods can worsen the pain, and it may also hurt to move the mouth to speak or chew food.

A canker sore can appear on a tonsil. In these cases, a person may have a sore throat that only affects one side of the throat, which they may mistake for tonsillitis.

There are three types of canker sores:

  • minor
  • major
  • herpetiform

Minor canker sores are a few millimeters in size. They are the most common type, accounting for 80% to 85% of all canker sores.

Major canker sores are 1 to 3 centimeters wide. Major canker sores can take up to 4 weeks to heal and may cause scarring. They cause more pain than a minor canker sore and can make it difficult to eat or drink without discomfort.

Herpetiform canker sores are multiple tiny canker sores, each about the size of a pinhead.

Herpetiform canker sores can join up to form a larger area, which can leave a scar.

It is not clear why some people are more likely than others to develop canker sores. However, there could be a genetic link, as canker sores tend to run in families in about 40% of cases.

Some potential risk factors for canker sores include:

If a person frequently gets canker sores, their doctor can help determine the underlying cause.

Doctors can typically diagnose canker sores based on the appearance of the sore and a person’s symptoms.

If canker sores keep coming back, a doctor may order tests to help identify the underlying cause. These can include blood tests and taking a swab of the affected area for laboratory analysis.

Canker sores usually heal without treatment. However, some remedies and medication can help ease pain.

Home remedies

People can make a saltwater rinse by dissolving half a teaspoon of salt in a glass of warm water. They can swill the rinse around the throat.

Drinking cold water or sucking on ice cubes may numb the pain a little. Eating soft frozen yogurt or ice cream could also help. It is best not to eat anything with sharp edges to avoid irritating canker sores further.

If a person has recurring canker sores, the following lifestyle changes may help:

Medical treatments

Medication can ease pain and reduce swelling, which can help encourage a canker sore to heal more quickly.

People can look for over-the-counter (OTC) gels and creams that contain an anti-inflammatory or pain relief agent and apply these directly to the ulcer. Some gels coat the canker sore to form a protective barrier that stops further irritation.

It can be difficult to reach a canker sore in the throat. Mouthwash can be a more effective way of reducing pain, swelling, and the risk of infection. A medicated or antimicrobial mouthwash may help, though alcohol-based mouthwash may sting.

A person can speak with a pharmacist or doctor before purchasing OTC medication to treat canker sores.

A person may need prescription medication for a severe canker sore. A doctor may recommend corticosteroids and immunosuppressants.

Laser therapy at a low level may help in cases of severe or recurrent canker sores. Although it is not a cure, it can speed up healing by drying out and disinfecting a canker sore. Silver nitrate cautery may also help with a major sore.

After a canker sore appears, the pain should start to ease within a few days. A minor canker sore should heal and disappear completely within 1 week.

It can take up to 4 weeks for major canker sores to heal, and they may leave a scar.

Some people are prone to canker sores and may get them multiple times. It is common for a person to get a canker sore between 3 and 6 times per year.

A person should contact a doctor if any of the following apply:

  • The sore lasts for more than 2 weeks.
  • The sore is very painful.
  • The sore causes difficulty eating or drinking.

Sometimes, teeth or gum problems can increase the risk of canker sores. A dentist can examine the mouth and suggest possible treatments.

Learn more about how long canker sores last.

Both canker sores and cold sores are small, painful lesions that cause a burning or tingling sensation.

However, canker sores appear inside the mouth or on the throat, while cold sores appear outside the mouth, usually around the lips.

The herpes simplex virus causes cold sores. They are contagious and spread through close contact, such as kissing or sharing a drink. Canker sores are not contagious.

A canker sore in the throat can be painful but it will usually heal on its own within around one week. Major canker sores may take longer to resolve.

A medicated mouthwash may help if it is hard to apply a cream or gel directly onto the ulcer. Drinking cold drinks and avoiding spicy foods may also help.

People who are prone to canker sores may find that they appear repeatedly. Avoiding foods that can irritate the throat and trying to reduce stress can help limit the frequency.

It is advisable to contact a doctor if a canker sore does not clear up within 2 weeks, or if the canker sore keeps returning.