Canker Sore On The Throat


Have you ever felt a painful burning sensation at the back of your throat when you swallow? That sensation could be due to a canker sore. A canker sore, also known as a mouth ulcer or aphthous ulcer, is a small reddish-white bump that arises in the inner lining of the mouth. These sores develop on the inside of cheeks or lips, although at times can affect the throat and tonsils

These start as small white or yellowish bumps with a reddish border, measuring up to 1-2 millimetres and are not contagious. Canker sores are painful and cause discomfort during eating and drinking.1

Read on to find out more about the types of canker sores, their causes, symptoms, and treatments, and when to reach out to a healthcare provider.

Types of canker sore

Canker sores are often mistaken for mouth ulcers and only be correctly identified upon physical examination.  

There are several types of canker sores:2,3

  • Minor canker sores: These are the most common type of canker sore and are usually <1 mm in size, and round or oval in shape. They typically appear on the inside of the cheeks, lips, or tongue.
  • Major canker sores: These are larger and deeper than minor canker sores and are very painful. In rare cases, they may not heal at all or may leave scarring once it does heal.
  • Herpetiform canker sores: These are numerous small, deep ulcers that frequently consolidate into larger, irregularly shaped ulcers. They are less common and typically appear in older adults.
  • Recurrent Aphthous Stomatitis (RAS): The most prevalent condition affecting the mouth is known as RAS. It is characterised by recurrent ulcerations of the mouth. They can be minor, major or herpetiform. RAS is responsible for 40% of recurrent ulcers in children and 25% of recurrent ulcers in adults.

It's important to note that canker sores are not the same as cold sores, which are caused by the herpes virus, and typically appear on the lip or around the mouth. If you are not sure about the type of sore you have, it is best to consult a GP for proper diagnosis and treatment.

Symptoms of a canker sore in the throat

Our throat has a soft layer called the mucous membrane protecting it. The ulcer forms within this layer making the throat and tonsils inflamed and painful. 

Common symptoms of a canker sore in the throat are:1,2

  • Pain that increases when chewing, swallowing, or talking, or having eaten spicy or acidic food
  • Burning and tingling sensation in the affected area
  • A one-sided throat pain. This tends to occur if the canker sore is present on the tonsils and is often mistaken for tonsillitis

You might be able to see the sore if you take a look towards the back of your throat, depending on where exactly it is. It will usually present as a small, singular sore, but in some cases, there may be multiple sores. 

Symptoms of severe canker sores in the throat are as follows:2

  • Swollen lymph nodes
  • An unusually large canker sore
  • Fever
  • Overall body fatigue

If these symptoms persist for weeks, you are most likely suffering from a severe case of canker sores and it is advised to reach out to your GP.

Causes of a canker sore in the throat

The exact cause of canker sores in the throat is not fully understood, but several factors are believed to contribute to their development. Some people may be more prone to developing canker sores due to a genetic factor, but they can also be brought on by an injury or due to dental work. However, they often seem to have no determinable cause. 

Canker sores may potentially result from various factors, such as:1,2,4

  • Hormonal changes and stress: Canker sores can become more common during times of hormonal changes, such as during menstruation in women. High levels of stress or emotional upset can also trigger canker sores in some people.
  • Nutritional deficiencies: A lack of certain vitamins and minerals, such as iron, vitamin B12, or folic acid, can increase the risk of canker sores.
  • Eating spicy or acidic foods: These foods are slightly irritating, and can trigger canker sores in some people.

How long do they last?

Canker sores typically last for one to two weeks. Minor canker sores will usually heal within 7 to 10 days, while major canker sores and herpetiform canker sores can take up to 6 weeks to heal. In some individuals, canker sores may recur periodically, and in rare cases, canker sores can become chronic.

Treatments and home remedies

Home remedies and over-the-counter medication can aid with pain relief and swelling reduction, which helps the healing of a canker sore.

Some home remedies for canker sores in the throat are:5

  • A salt water rinse: Mix 1 teaspoon of salt in 1 cup of warm water and use it as a mouthwash to gargle with twice a day. 
  • Hydrogen peroxide: Mixing hydrogen peroxide with water in equal parts and using it as a mouthwash can help get rid of the bacteria in the sore and promote healing.
  • Honey: You can use honey to soothe your throat and treat canker sores. Try adding it to a calming tea, like chamomile, and consuming several cups throughout the day. 
  • Vitamin supplements: Taking vitamin B12 or folic acid supplements may help prevent canker sores or reduce their frequency.

Several medical treatments for canker sores in the throat include:1,2,6

  • Medicated/anti-bacterial mouthwash: Reaching a throat canker sore can be challenging. A more efficient technique to lessen discomfort, bruising, and the danger of infection is using an antibacterial mouthwash.
  • Painkillers: Paracetamols such as ibuprofen are over-the-counter medicine you can take to relieve the pain and swelling caused due to canker sores. The ulcer can be treated directly using gels and lotions that contain a painkiller. Some gels cover the canker sore to create a barrier of protection that prevents additional irritation.
  • Prescription creams, gels, and medication: Your doctor may prescribe a cream or gel that contains a higher concentration of benzocaine or lidocaine to numb the sore and reduce pain. Doctors may prescribe steroids to quicken the healing of sores and antibiotics if an infection is also present. 

Your GP can suggest certain vitamins or supplements if you have canker sores that are the result of nutritional deficiencies. In case of severe canker sores in the throat, your doctor could recommend cauterization (burning the affected tissue using a laser) as it can sanitise the region, lessen discomfort, and help towards a speedy recovery.

When to seek medical attention

You should seek medical attention if you have a fever, swollen lymph nodes, or if the sore starts to spread or does not heal after 2 weeks. Additionally, you should see a doctor if you have a large canker sore, multiple canker sores, or if the sore is causing discomfort when eating, swallowing or talking. Your doctor can examine the sore, rule out any other conditions, and recommend the best treatment plan for you.1,2


Canker sores in the throat are small, painful ulcers that can cause discomfort when swallowing and may last for one to two weeks. They can be caused by injury, stress, certain foods, and other factors. Home remedies and over-the-counter medications may help relieve the symptoms. In severe cases, or if the sore does not heal after two weeks, it is best to seek medical attention. Your GP can examine the sore and recommend the best treatment plan for you based on the type and severity of your canker sore.


  1. Canker sores (Mouth ulcers): Overview [Internet]. Institute for Quality and Efficiency in Health Care (IQWiG); 2019. Available from: 
  1. Canker sore (Aphthous ulcer): what it is, causes & treatment [Internet]. Cleveland Clinic. Available from: 
  2. Edgar NR, Saleh D, Miller RA. Recurrent aphthous stomatitis: a review. The Journal of clinical and aesthetic dermatology. 2017 Mar;10(3):26. 
  3. Everything you ever wanted to know about canker sores [Internet]. Cedars-Sinai. Available from: 
  4. Canker sore remedies that actually work [Internet]. Verywell Health. Available from: 
  5. Plewa MC, Chatterjee K. Aphthous stomatitis. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022. Available from: 
This content is purely informational and isn’t medical guidance. It shouldn’t replace professional medical counsel. Always consult your physician regarding treatment risks and benefits. See our editorial standards for more details.

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Jeffy Joseph Vinohar

MSc. Oncology, University of Nottingham, England

Jeffy is an aspiring academic scientist with a bachelors in Biomedical sciences, Biotechnology with a keen interest in cancer studies. During her masters she aimed to learn more about making healthcare accessible and solutions to reduce healthcare inequalities in the field of oncology.
She currently interested in paediatric neuro-oncology and developing less invasive therapeutics for it by obtaining a PhD in coming years, while being involved with simplifying scientific research into health awareness articles.

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