Mouth ulcers – causes, symptoms, types and other complications

Mouth ulcers

Mouth ulcers are types of sores which appear in the mouth and they are often on the inside of the cheeks. They are also known as canker sores or aphthous ulcers. They can be painful when you are drinking, eating or when you brush your teeth. When you have occasional mouth ulcers, then they are usually harmless and they clear up on their own. But if your mouth ulcers last longer than three weeks or they keep coming back, then you should seek medical help. You should know that the mouth ulcers cannot be caught from someone else. It is known fact that up to one in five people get recurrent mouth ulcers. They are very common and they can be usually managed at home without seeing your doctor or dentist. They are usually oval or round sores which commonly appear inside the mouth on the tongue, cheeks and lips. Mouth ulcers can be grey, yellow, red or white in color and swollen. Also it is possible to have more than one ulcer at a time and they can grow or spread. You should not confuse the mouth ulcers with cold sores. Cold sores are small blisters which develop around the mouth or on the lips. Also the cold sores begin with a burning, itching or tingling sensation around the mouth.

Mouth ulcers symptoms

You may have a mouth ulcer if you have:

  • Sores in your mouth that are round, grey or white in color, with a red border or edge
  • A painful sore or sores which are inside your mouth, soft palate (the back portion of the roof of your mouth), on the tongue or inside your cheeks

When someone has severe mouth ulcers, then they can experience:

  • Swollen lymph nodes
  • Physical sluggishness
  • Fever

Mouth ulcers

Mouth ulcers causes

There are many cases when the cause for mouth ulcers is not known. The most single ulcers are caused by damage which is done to the lining inside of the mouth. Here are some examples of damages:

  • A defective filling
  • Hard food
  • Poorly fitting dentures
  • Accidentally biting the inside of your cheek or a sharp tooth

It is not always known what is causing mouth ulcers to keep returning. Here are some triggers:

  • Stopping smoking – when you first stop smoking, you may develop mouth ulcers [1]
  • Toothpaste containing sodium lauryl sulphate [2]
  • Eating certain foods – such as wheat flour, tomatoes, cheese, strawberries, almonds, peanuts, coffee, spicy foods and chocolate
  • Hormonal changes – some women develop mouth ulcers during their monthly period [3]
  • Stress and anxiety [4]

Also it is thought that genes can play a role in it. There are some studies in which are said that around 40% of people who are getting mouth ulcers have reported that their families also had mouth ulcers.

Also there are some cases when ulcers can be caused by medical conditions such as:

  • Behcet’s disease: This type of diseases is a rare and poorly understood condition which is causing swelling of the blood vessels [5]
  • Weakened immune system: Lupus or HIV can weaken your immune system [6]
  • Reactive arthritis: This is a condition which is causing inflammation in many places in the body, usually as a reaction to an infection
  • Coeliac disease: This is a common digestive condition where a person has an adverse reaction to gluten [7]
  • Viral infections: In which are included hand, foot and mouth disease, chickenpox and cold sore virus
  • Crohn’s disease: This is a long – term condition which is causing inflammation of the lining of the digestive system [8]
  • Vitamin B12 or iron deficiency

In some cases mouth ulcers can be caused by some medications or treatments such as

  • Nicorandil
  • NSAIDs
  • Beta – blockers
  • A side effect of radiotherapy or chemotherapy

Types of mouth ulcers: Here are the main types of mouth ulcers:

  • Minor ulcers: These ulcers are around 2 – 8 mm in diameter and they usually clear up in ten days to two weeks.
  • Major ulcers: Major ulcers are deeper and bigger and they are often with an irregular or raised border. Major ulcers can take several weeks to heal and they can leave a scar in the mouth.
  • Herpetiform ulcers: If you have this type of mouth ulcers, then you have a cluster of dozens of small sores the size of pinheads.


[1] McRobbie H, Hajek P, Gillison F. The relationship between smoking cessation and mouth ulcers. Nicotine & Tobacco Research. 2004;6(4):655-9.

[2] Yang Y, Zhang T, Dong Z, et al. Short-term efficacy of pudilan keyanning toothpaste in treatment of minor recurrent aphthous ulcers. Evidence-Based Complementary and Alternative Medicine. 2016;2016:9125327.

[3] Maheswaran T, Yamunadevi A, Ilayaraja V, et al. Correlation between the menstrual cycle and the onset of recurrent aphthous stomatitis. Journal of Indian Academy of Dental Specialist Researchers. 2015;2(1):25.

[4] Gallo CdB, Mimura MAM, Sugaya NN. Psychological stress and recurrent aphthous stomatitis. Clinics (Sao Paulo). 2009;64(7):645–8.

[5] Taylor J, Glenny AM, Walsh T, et al. Interventions for managing oral ulcers in Behçet’s disease. Cochrane Database of Systematic Reviews. 2014;2014(9):CD011018.

[6] University of Gothenburg. New research comes to terms with old ideas about canker sores. Science Daily. 2017.

[7] Beyond Celiac. Kids, cancer sores and celiac disease. 2020. Retrieved from

[8] Woo VL. Oral manifestations of Crohn’s disease: A case report and review of the literature. Case Reports in Dentistry. 2015;2015:830472.


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