What causes mouth ulcers?

In many cases, the reason for mouth ulcers is unclear. Most single mouth ulcers are caused by damage to the lining inside of themouth. For example:

  • accidentally biting the inside of your cheek or a sharp tooth
  • poorly fitting dentures
  • hard food
  • a defective filling

Its not always clear what causes mouth ulcers that keep returning, but triggers are thought to include:

  • stress and anxiety
  • hormonal changes some women develop mouth ulcers during their monthly period
  • eating certain foods such as chocolate, spicy foods, coffee, peanuts, almonds, strawberries, cheese, tomatoes and wheat flour
  • toothpaste containing sodium lauryl sulphate
  • stopping smoking when you first stop smoking, you may develop mouth ulcers

Your genes are also thought to have a rolearound 40% of people who keep gettingmouth ulcers report that it runs in their family.

Medical conditions

Mouth ulcers can sometimes be caused by certain medical conditions, such as:

  • viral infections including the cold sore virus , chickenpox , and hand, foot and mouth disease
  • vitamin B12 or iron deficiency
  • Crohn's disease a long-term condition that causes inflammation of the lining of the digestive system
  • coeliac disease a common digestive condition where a person has an adverse reaction to gluten
  • reactive arthritis a condition that causes inflammation in various places in the body, usually as a reaction to an infection
  • weakened immune system for example, due to HIV or lupus
  • Behets disease a rare and poorly understood condition that alsocauses swelling of the blood vessels

Medications and treatments

Mouth ulcers can sometimes be caused by certain medications or treatments, such as:

  • non-steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen
  • nicorandil a medication sometimes used to treat angina
  • beta-blockers used to treat conditions such as angina, high blood pressure and abnormal heart rhythms
  • a side effect of chemotherapy or radiotherapy this is known as mucositis
Content supplied by the NHS Website

Medically Reviewed by a doctor on 21 Dec 2018