Noma usually begins as an ulcer on the gums and rapidly spreads into the jawbone, cheek, and facial soft tissues.

Noma is most common in impoverished environments with poor healthcare infrastructure; as a result, many cases go undiagnosed, untreated, and unreported.

[3] Initially, there may be a small ulcer in the mouth which progresses into necrotizing gingivitis – painful bleeding of the gums and inter-dental papillae.

This is followed by a rapid spread of the infection resulting in more general inflammation of the mouth and lips, facial edema, and foul breath.

If untreated, within a few days the necrotizing infection progresses into the facial muscles, the skin, and the upper and lower jaw resulting in tissue destruction and sloughing.

[6][7] Noma neonatorum is a severe infection affecting very young or newborn children in impoverished environments.

[8] The World Health Organization divides noma into five stages: Acute necrotizing gingivitis, edema, gangrenous, scarring, and sequelae.

A high-protein diet, Vitamin A supplements, and patient education on oral hygiene are also recommended to prevent noma from progressing to the acute stages.

If the patient is malnourished and has recently been sick with an infectious disease, such as measles or chickenpox, they are at more risk for developing noma.

Other symptoms at this stage include fever, drooling, fetid breath, lymphadenopathy (swollen lymph nodes), and difficulty eating.

The patient may experience trismus (difficulty moving/opening the jaw), scars will form, and any exposed teeth will set in place.

[9] As of December 2023[update], most people who acquire this disease are between the ages of two and six years old, living in the poorest countries of the world.

In 1998 The World Health Organization estimated that 140,000 new cases were occurring each year, with a 90% fatality rate, and a total of 770,000 surviving with scarring or disfigurement.

The prognosis is much better with treatment; if children have access to medical care, the mortality rate drops to under 10 percent.

[14][12][15] Predisposing factors include:[15][16][17] When noma is detected early, its progression can be rapidly halted through basic hygiene, antibiotics, and improved nutrition.

The World Health Organization recommends using amoxicillin and metronidazole in tandem to treat stage I noma (acute necrotizing gingivitis), along with the use of chlorhexidine and hydrogen peroxide to clean the mouth and gums.

Known in antiquity to such physicians as Hippocrates and Galen, noma was once reported around the world, including in Europe and the United States.

A European scientist, Gabriel Lund, attributed noma to poverty, cramped living conditions, and malnutrition in 1765.

[12] With improvements in hygiene and nutrition, Noma has disappeared from industrialized countries since the 20th century, except during World War II when it was endemic to the Auschwitz and Belsen concentration camps.

In a study of 7,185 noma sufferers across Nigeria, only 19% reported going to a hospital or medical center upon discovering a facial lesion.

In other countries, such as Ethiopia, international charities work in collaboration with the local health care system to provide complex reconstructive surgery which can give back facial functions such as eating, speaking, and smiling.

Teams of volunteer medics coming from abroad are often needed to support the local capacity to address the most severe cases, which can be extremely challenging even for senior maxillofacial surgeons.

[26] On 10 June 2010, the work of such volunteer surgeons was featured in a UK BBC Two documentary presented by Ben Fogle, Make Me a New Face: Hope for Africa's Hidden Children.