Mouth Ulcers

This symptom may often make a GP feel baffled – largely because it tends to be overlooked, or dealt with only briefly, during medical training. In fact common causes are simple to detect and treat, and it is clearly important to spot the occasional serious problem at an early stage. Examination could hardly be simpler, and a dentist may well have a clearer idea if referral is necessary in more obscure cases.

Published: 2nd August 2022 | Updated: 18th August 2022

Differential diagnosis

Common Diagnoses

  • Trauma
  • Recurrent Aphthous Ulceration (RAU)
  • Acute Necrotising Ulcerative Gingivitis (ANUG)
  • Thrush
  • Deficiency States (Iron, B12 and Folate)

Occasional Diagnoses

  • Coxsackie Virus: Herpangina, Hand, Foot and Mouth
  • Inflammatory Bowel Disease: Ulcerative Colitis and Crohn’s Disease
  • Coeliac Disease
  • Herpes Simplex and Zoster
  • Glandular Fever (EBV): Infectious Mononucleosis
  • Erosive Lichen Planus

Rare Diagnoses

  • Carcinoma: Squamous Cell, Salivary Gland
  • Autoimmune: behçet’s Syndrome, Pemphigoid, Pemphigus, Bullous Erythema Multiforme
  • Syphilitic Chancre or Gumma
  • Leukaemia, Agranulocytosis (May be Iatrogenic)
  • Tuberculosis
  • HIV Infection

Ready reckoner

Key distinguishing features of the most common diagnoses

TraumaRAUANUGThrushDeficiency States
Usually in CropsNoYesPossibleYesYes
White Buccal PlaquesNoNoNoYesNo
Bleeding GumsNoNoYesNoNo
Mucosal PallorNoNoNoNoYes

Possible investigations

Likely: FBC, ferritin.

Possible: Urinalysis, vitamin B12 and folate, coeliac screen.

Small Print: Swab, autoantibody screen, syphilis and HIV serology, biopsy.

  • FBC: Essential basic investigation for anaemia and rarer blood dyscrasias. Ferritin for iron deficiency.
  • Urinalysis: Check for glycosuria. Underlying diabetes may predispose to infective causes (especially Candida).
  • Vitamin B12 and folate: To establish underlying vitamin deficiency (especially if MCV raised).
  • Coeliac screen: Anti-endomysial and anti-gliadin antibodies suggest coeliac disease if positive.
  • Swab: May help confirm doubtful diagnosis of ANUG – confirms presence of Vincent’s organisms.
  • Autoantibody screens and HLA tests may be useful if autoimmune causes are suspected.
  • Syphilis or HIV serology: If syphilis or HIV are suspected.
  • Biopsy: Required in persistent ulcer of uncertain aetiology (secondary care investigation).

Top Tips

  • Consider vitamin or iron deficiency, especially if the patient has glossitis and angular cheilitis as well as oral ulceration.
  • The patient with sore, ulcerated gums and foul halitosis has ANUG; the smell is sometimes apparent as soon as the patient walks in.
  • Patients with RAU often believe they are suffering from a vitamin deficiency; in fact, this is rarely the case, but be sure to broach this with them and consider a blood test as this may reinforce your reassurance.
  • Enquire about skin problems elsewhere in an obscure case – this may give a clue to the precise diagnosis.
  • Faucial ulceration and petechial haemorrhages of the soft palate and pharynx are likely to be caused by glandular fever.

Red Flags

  • A solitary, persistent and often painless ulcer could be malignant – especially in smokers. Refer urgently to the oral surgeon for biopsy.
  • Ask about bowel function – diarrhoea, abdominal pain and bloodstained stools with mucus suggest associated inflammatory bowel disease.
  • Don’t forget to enquire about medication – blood dyscrasias are a rare but significant side effect of some treatments (e.g. carbimazole), and oral ulceration may be the first sign.
  • Oral candidiasis is common in the debilitated and those with dentures, but much less so in the otherwise apparently fit. In the latter cases consider underlying problems such as immunosuppression or diabetes.
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Website disclaimer

Pulse Reference is based on the best-selling book Symptom Sorter.

The experts behind Pulse Reference are Dr Keith Hopcroft who is the co-author of Symptom Sorter, a GP in Essex and Pulse’s editorial advisor and Dr Poppy Freeman, a GP in Camden and also a clinical advisor to Pulse.

This website is for clinical guidance only and cannot give definitive diagnostic information. Practitioners should work within the limits of their individual professional practice, seek guidance when necessary and refer appropriately.