Acute necrotising ulcerative gingivitis is an infection of the gingival tissues. This post will look at the signs and symptoms, diagnosis and management of cases of acute necrotising ulcerative gingivitis.

What is Acute Necrotising Ulcerative Gingivitis?

Acute Necrotising Ulcerative Gingivitis, or ANUG, is an example of a necrotising periodontal conditions. It is a relatively common, non-contagious infection of the gingival tissues. 

It is the mildest of the necrotising periodontal conditions, with necrotising ulcerative periodontitis and necrotising ulcerative stomatitis being the more severe conditions. Ultimately, this can lead to cancrum oris (noma) which is extensive infection and often fatal.

Causes of ANUG?

ANUG is cause by a mixed fusiform/spirochaete bacterial infection, primarily caused by Prevotella intermedia, Fusobacterium species and Treponema species. It is often described as an opportunistic infection that occurs when there is an impairment of the host immune response.

The mechanisms by which the damage occurs to gingival tissues is not completely clear, however four zones have been identified in the gingival tissues:

  • Bacterial zone (the only zone found in situations aside from ANUG)
  • Neutrophil-rich zone
  • Necrotic zone
  • Spirochaetal infiltration zone

Damage occurs through direct toxic effects and indirect effects. Predisposing factors are also important in leading to ANUG in patients.

Microbial causes of ANUG
Evidence of some of the microbes involved in causing ANUG (

Predisposing factors

There are multiple predisposing factors that are helpful to look out for in a patient who presents with potential ANUG:

  • Immune suppression – particularly patients with HIV infection (it may even be the first symptom presentation of someone with unknown HIV diagnosis)
  • Stress
  • Smoking
  • Poor diet or malnutrition
  • Pre-existing gingival conditions and poor oral hygiene

ANUG is more common in developing countries, often in children and where there is a high incidence of malnutrition or infections.

Signs and symptoms

There are a range of signs and symptoms that may be noted in ANUG to a varying degree. The first three must be present for diagnosis:

  • ‘Punched out’ interdental papillae where interdental papillae are ulcerated and have necrotic tissue
  • Severe gingival pain – often well localised to the gingival areas
  • Profused gingival bleeding, often with a lack of stimulus
  • Halitosis
  • A metallic taste

There is usually an absence of pyrexia, malaise and lymphadenopathy (unless there is another underlying condition that is predisposing the patient to ANUG).

Presentation of ANUG
An example of ANUG – there is evidence of ‘punching out’ of the interdental papillae.

Diagnosis and Necrotising Ulcerative Periodontitis/Stomatitis

Diagnosis is typically clinical and based on the presenting signs and symptoms.

Much like regular gingivitis, ANUG does not demonstrate attachment loss. If attachment loss has occurred, then the patient has progressed to necrotising ulcerative periodontitis (NUP). If the attachment loss and disease progresses beyond the mucogingival junction, then the patient has developed necrotising ulcerative stomatitis (NUS).


Management of the acute condition often involves but local and systemic measures:

  • Thorough irrigation and debridement of infected areas to remove and plaque and calculus that may be contributing to the condition.
  • Oral hygiene instruction should be given to ensure the patient is managing the areas at home. A chlorhexidine mouthwash may be prescribed to aid with plaque control.
  • A hydrogen peroxide mouthwash (up to 6%) to be used up to three times a day to target the microbes.
  • Metronidazole 400mg three times a day for 3 days (usually if systemic involvement or persistent infection)

Other predisposing factors should be considered:

  • Smoking cessation advice should be given if necessary
  • Referral for stress management
  • Dietary advice
  • In recurrent infection, a consideration should be given to causes of immunosuppression

Following settling of the acute phase, thorough scaling and root surface treatment should be carried out if necessary, along with regular oral hygiene instruction.


  • Acute necrotising ulcerative gingivitis (ANUG) is an opportunistic, non-infectious necrotising periodontal condition.
  • It is caused by a mixed microbial infection, primarily of PrevotellaFusobacterium and Treponema species.
  • There are many predisposing factors, including immunosuppression, stress and smoking.
  • Diagnosis is clinically determined.
  • ANUG can progress to necrotising ulcerative periodontitis or stomatitis.
  • Management involves local and potentially systemic methods, with long-term correction of predisposing factors.


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BDS (Hons.) MFDS RCPS (Glasg.) Cert Med Ed FHEA - Currently working as a Speciality Doctor in OMFS and as an Associate Dentist


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