Mouth ulcers are common and should clear up on their own within a week or two. Rarely a sign of anything serious, they may be uncomfortable to live with. 

Most people will experience a mouth ulcer at some point in their life either caused by a minor injury or recurring ulcers.

While no one really knows what causes these small lesions in the mouth, triggers include hypersensitivity, infection, hormones, stress, and not getting enough of some vitamins. Mouth ulcers are incredibly common, with almost everyone having at least one in their life. Not only is it possible to have more than one mouth ulcer at a time, but they may in fact spread or grow. 

 There are essentially two types of mouth ulcers: 

  • Once off mouth ulcers are generally caused by a sensitivity or minor injury. 
  • Recurring mouth ulcers (aphthous stomatitis), which affect about one in five people, often first appearing during childhood or adolescence. 


Mouth ulcers are not contagious and should not be confused with cold sores. Mouth ulcers are usually round or oval and can be white, red, yellow, or grey in colour. They occur inside the lips, inside the cheeks, on the bottom of the mouth, or on the gums or tongue. Cold sores on the other hand are small blisters that develop on the lips or around the mouth and often begin with a tingling, itching, or burning sensation, the UK National Health Service (NHS) explained.  


According to Health Direct Australia, mouth ulcers can be caused or triggered by: 

  • Stress, anxiety, or hormonal changes 
  • Any injury or damage to the mouth, such as from sharp teeth, dentures, or braces 
  • A reaction to certain foods, drugs, or toothpastes 
  • Some infections and diseases, like coeliac disease 
  • Certain medications and medical treatments 
  • Vitamin deficiencies 

Herpes simplex often causes mouth ulcers in children and some adults. Other less common viral and bacterial infections may cause mouth ulcers, but this is rare. According to the Oral Health Foundation, mouth ulcers can also be caused by anaemia and occasionally by other blood disorders, and some skin or gastrointestinal diseases.  


While there’s no quick fix, mouth ulcers generally just need time to heal. That said, there are several things patients can do to speed up healing, prevent infection, or reduce pain. The UK National Health Service recommends avoiding things that will irritate a mouth ulcer: 

The focus of management is relieving pain and discomfort and helping the mouth ulcer heal more quickly. As pharmacist you can recommend several treatments: 

  • Antimicrobial mouthwash or spray 
  • A painkilling tablet, mouthwash, lozenge, gel, or spray 
  • Corticosteroid lozenges 
  • A salt (saline) mouthwash 

Although most mouth ulcers are harmless, a long-lasting mouth ulcer is sometimes a sign of mouth cancer. Advise patients to consult a doctor or dentist if their ulcer does not heal within three weeks.