How does a mouth ulcer form?

How does a mouth ulcer form?

One minute your mouth is clear, and the next, you accidentally bite your tongue or a sliver of almond jabs your gums, and there it is – a break in the skin that causes a mouth ulcer. Ulcers, also known as canker sores, are red, yellow or grey and usually disappear after a few days – but oh boy, do they hurt! 

Sometimes, they stick around and irritate a painful little ridge on the side of your mouth. They can also appear as a burning, red slash on your tongue.

Then, there are the ulcers that throb and cling to the mucous membrane a lot longer than they should.  Of course, having a painful mouth sore is cause for concern. 

The nature of ulcers

Mouth ulcers are usually on the tongue, inside the mouth, on the inner cheeks and lips and on the roof of the mouth. They are common and usually appear one at a time and disappear within a week to two weeks. 

The signs and symptoms of mouth ulcers are: fever, fatigue, swollen lymph nodes and severe pain in the mouth that makes eating difficult, says Oral Health Foundation. 

However, mouth ulcers are not contagious as they are not related to cold sores (caused by the herpes virus and appear on the lips or around the mouth). 

Ulcers happen from trauma, environmental factors, medication or systemic disease where the ulcers may be the only visible indicator of underlying conditions such as gastrointestinal diseases and cancer. 

The three common types of ulcers: 

  • Minor mouth ulcers are the most common and usually occur about thrice a year – smaller than a centimetre, they heal within a week with no scars.
  • Less common major mouth ulcers are larger than a centimetre and last up to two weeks or more. An ulcer that grows larger is painful, red and is close to the throat, requires a visit to the doctor. 
  • Rare and usually as a group of small ulcers, Herpetiform mouth ulcers should heal within a week. 

Herpetiform mouth ulcers are the fusion of multiple pinpoint lesions. Herpetiform ulcers become larger and very painful. They get their name from their striking similarity to herpes. But, herpetiform ulceration is not caused by the herpes simplex virus.

The causes of ulcers 

Some ulcers which fall within the trauma category can usually be avoided, says the NHS.

These occur when: you bite the inside of your mouth; have rough fillings, dentures or a sharp tooth; cuts or burns from eating hot or hard foods; you have food allergies or intolerance; damages from a toothbrush or toothpaste; smoking, alcohol and drug abuse; eating acidic fruits such as lime, oranges, pineapple and tomatoes; and the modern-day malaise of stress, anxiety and exhaustion. 

Ulcers can be allergic reactions to medications and treatments such as painkillers and antibiotics; chemotherapy and radiation used in cancer therapy; and nutritional deficits, including vitamin B12, zinc, folic acid, or iron. 

Recurring ulcers that are larger and last longer are:

  • Usually a result of hormonal imbalance.
  • Acid reflux and peptic ulcer disease.
  • Weakened immune systems from HIV / AIDS and diabetes.
  • Autoimmune disorders such as systemic lupus erythematosus and Bechet’s disease.
  • Gastrointestinal conditions like celiac and Crohn’s disease.
  • Infectious diseases like the herpes simplex virus.
  • Hand, foot and mouth disease and mononucleosis. 

Infected mouth ulcers need antibiotics.

Sometimes your mouth ulcer can become secondarily infected. This happens when we don’t keep them clean, or they get injured, and bacteria enters. The site becomes more tender, and pain increases. Watch out for redness, or a general feeling of unwellness, with a high temperature. Secondary bacterial infections are uncommon but possible and but may need antibiotic treatment.

Is it mouth cancer?

In a few cases, long-lasting mouth ulcers have been linked to cases of mouth cancer. These types of mouth ulcers usually present on top of or underneath the tongue, although you can get them in other areas of the mouth.

Risk factors for mouth cancer, according to NHS, include:

  • smoking of using tobacco-based products.
  • Drinking alcohol. Heavy drinkers who also use tobacco have a much higher risk compared to the population at large.
  • Infection with the human papillomavirus (HPV) – the virus that causes genital warts.

It’s essential to detect mouth cancer as early as possible, but your mouth ulcer most likely isn’t cancerous. Regular dental check-ups are the best way to see the early signs. Early detection is the number 1 lifesaver. 


You can heal most ulcers with simple home remedies such as saltwater or bicarbonate of soda gargles, coconut oil pulling, applying a cool teabag or an ice cube or a dab of milk of magnesia on the sore. The doctor may prescribe medicated mouthwashes. 

To speed up healing, experts say:

  • Use a soft-bristled charcoal brush.
  • Use a straw for drinks.
  • Eat softer foods.
  • Eat a diet rich in vitamins A, C and E. 

While you should avoid the following: 

  • Acidic fruits and vegetables
  • Fizzy drinks, fruit juices, very hot or acidic drinks, coffee, smoking, alcohol and drugs
  • Very spicy and salty foods 
  • Rough, crunchy food such as toast and crisps
  • Chewing gum containing sodium lauryl sulphate
  •  using toothpaste containing sodium lauryl sulphate. 

Long-term prevention remains the best, including regular visits to the dentist, keeping the mouth as clean and healthy as possible with at least two brushings and one flossing a day. 

Coupled with eating whole foods with lots of green vegetables, staying well hydrated, breathing in the fresh air out in nature and practising stress management, all contribute to a healthier lifestyle. 


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