Necrotizing Fasciitis (Flesh-Eating Bacteria)

Medically Reviewed by Zilpah Sheikh, MD on November 16, 2023
5 min read

Necrotizing fasciitis, also known as flesh-eating bacteria or flesh-eating disease, is a rare infection of the skin and tissues below it. "Necrotizing" means causing tissue death, and "fasciitis" refers to fascia inflammation, which is tissue under the skin. 

Necrotizing fasciitis is a form of necrotizing soft tissue infection (NSTI). These life-threatening infections affect the skin, muscles, and soft tissue and cause patches of tissue to die. It spreads quickly and aggressively in an infected person, causes tissue death at the infection site, and can be deadly if not treated right away.

Every year, between 700 and 1,150 cases are diagnosed in the U.S. Up to 1 in 5 cases of necrotizing fasciitis result in death. It rarely happens in children.

Necrotizing fasciitis includes two types:

Type I, or polymicrobial. This type happens when more than one bacteria, usually a mix of aerobic and anaerobic bacteria, cause the infection.

Type II, or monomicrobial. The monomicrobial form is typically caused by one bacteria, group A streptococcus or Staphylococcus aureus bacteria.

Necrotizing fasciitis is commonly caused by group A streptococcus (GAS) bacteria. That's the same type of bacteria that causes strep throat. But, several types of bacteria, including Vibrio vulnificus (bacteria that live in water), staphylococcus, and others, have also been linked to the disease.

Necrotizing fasciitis happens when these types of bacteria infect the superficial fascia, a layer of connective tissue below the skin.

Flesh-eating bacteria transmission

The bacteria that cause necrotizing fasciitis can enter the body through:

  • Surgical wounds
  • Puncture wounds or an injury that doesn't break the skin
  • Burns
  • Minor cuts and scrapes
  • Insect bites
  • Abrasions

In some cases, it is unknown how the infection began. Once it takes hold, the infection rapidly destroys muscle, skin, and fat tissue.



Having a weakened immune system and certain diseases may make you more likely to get necrotizing fasciitis. Health conditions that may raise your risk include:

  • Alcohol abuse
  • Cancer
  • Chickenpox in childhood
  • Cirrhosis (permanent liver damage)
  • Diabetes
  • Heart disease affecting the heart valves
  • Chronic kidney disease
  • Lung disease, including tuberculosis
  • Peripheral vascular disease
  • Steroid use
  • Use of injectable or IV drugs

In very rare cases, dental, tonsil, salivary gland, and sinus issues can cause facial necrotizing fasciitis.

The early symptoms of an infection with flesh-eating bacteria usually appear within the first 24 hours of infection. Symptoms are similar to those of other conditions like the flu or a less serious skin infection. The early symptoms are also similar to common post-surgical complaints, such as:

  • Serious pain, including areas other than the skin that look swollen or red 
  • Inflammation
  • Fever
  • Nausea

Symptoms often include a combination of the following:

  • Increasing pain in the general area of a minor cut, abrasion, or other skin opening
  • Pain that is worse than would be expected from the appearance of the cut or abrasion
  • Redness and warmth around the wound, though symptoms can begin at other areas of the body
  • Flu-like symptoms such as diarrhea, nausea, fever, dizziness, weakness, and general malaise
  • Intense thirst due to dehydration

More advanced symptoms happen around the painful infection site within 3 to 4 days of infection. They include:

  • Swelling, possibly along with a purplish rash
  • Large, violet-colored marks that turn into blisters filled with dark, foul-smelling fluid
  • Discoloration, peeling, and flakiness as tissue death (gangrene) happens
  • Dizziness, fatigue, or nausea

Critical symptoms, which often happen within 4 to 5 days of infection, include:

Flesh-eating bacteria (necrotizing fasciitis) affects the body quickly, making early diagnosis important to survival.

The doctor will examine you and review your symptoms. Having flesh-eating bacteria is a medical emergency, and if a doctor suspects you may have it, you’ll likely be admitted to a hospital and get tested there.

Tests to diagnose flesh-eating bacteria (necrotizing fasciitis) include:

Blood tests. People with flesh-eating bacteria have high levels of white blood cells.

Tissue biopsy. You may need exploratory surgery to remove some of the tissue from the infected area. The tissue is sent to a lab to identify the particular bacteria that’s causing the infection. But you’ll be given some medicine to treat the infection before test results are back.

CT scan. A CT scan can show your doctor where fluid and pus are collecting in the body. It also shows the presence of gas bubbles under the skin, which helps confirm the diagnosis.

Household members and others who have had close contact with someone with necrotizing fasciitis should be tested for the disease if they have symptoms of an infection.

If you're infected with flesh-eating bacteria, you will get several types of treatment. The extent of treatment depends on the stage of the disease when treatment is started but can include:

  • Intravenous (IV) antibiotic therapy
  • Surgery to remove damaged or dead tissue in order to stop the spread of infection
  • Medications to raise blood pressure
  • Amputations of affected limbs, in some cases
  • Hyperbaric oxygen therapy to preserve healthy tissue
  • Cardiac monitoring and breathing aids
  • Blood transfusions
  • Intravenous immunoglobulin, which helps the body fight infection

Serious complications are common and may include:

  • Sepsis
  • Shock
  • Organ failure
  • Loss of an arm or leg due to amputation
  • Severe scarring
  • Death


Washing your hands with soap and water or using an alcohol-based hand sanitizer is one of the best steps you can take to prevent flesh-eating bacteria and other skin infections.

You can also prevent skin infections by taking these steps:

  • After cleaning, cover an oozing, draining, or open wound with a clean, dry bandage.
  • Get treated by a doctor if you have a serious or deep wound, such as a puncture or gunshot.
  • Don’t go swimming or use a hot tub if you have an open wound or skin infection.

There’s no vaccine available to prevent flesh-eating bacteria infection.

Early diagnosis and immediate, aggressive treatment are critical when it comes to fighting this rare skin infection. Many people need more than one procedure to remove damaged, infected tissue. If you have red, swollen skin and it’s not going away, make an appointment with your doctor.