What Is Necrotizing Fasciitis?

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Necrotizing fasciitis is a rapidly progressing infection of soft tissue. The name can be broken down into two different definitions:

  • Necrotizing: The death of tissue.
  • Fasciitis: Inflammation of the fascia, which is a thin casing of connective tissue that surrounds and holds every organ, blood vessel, bone, nerve fiber, and muscle in place.

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A person with necrotizing faciitis on their leg

Reproduced with permission from © DermNet New Zealand and © Waikato District Health Board www.dermnetnz.org 2023.

Several different types of bacteria can be responsible for causing necrotizing fasciitis, and there are a few different types of the disorder, including type I, II, and III. Other names commonly used for necrotizing fasciitis include:

  • Flesh-eating bacteria
  • Flesh-eating disease
  • Streptococcal gangrene
  • Suppurative fasciitis

The condition is rare, but it progresses very quickly and if left untreated it could become severe enough to cause death. Therefore, it’s vital to seek immediate medical treatment any time symptoms of necrotizing fasciitis are present, particularly after an injury or a surgical procedure.

Types of Necrotizing Fasciitis

There are several types of necrotizing fasciitis—these include:

  • Type I: This polymicrobial type of necrotizing fasciitis involves more than one type of bacteria and often occurs in those with diabetes and other health disorders, as well as in the elderly population.
  • Type II: This type of necrotizing fasciitis—known as hemolytic streptococcal gangrene—is characterized by isolation of S. pyogenes with or without other bacterial species. Staphylococcus aureus is the most common species found in coinfection cases. Type II necrotizing fasciitis may occur in any age group, including young, healthy people, as well as older folks and those with health conditions. Type II necrotizing fasciitis is often referred to as a type of “flesh-eating bacteria.”
  • Type III: This type of necrotizing fasciitis is caused by clostridium and is referred to as gas gangrene. It usually occurs after a person has surgery or has undergone a significant injury with deep wounds. It results in gas under the skin, which makes a crackling sound that has been medically coined “crepitus.” Heroin users, injecting a specific type of the drug called “black tar heroin,’’ are prone to becoming infected with this type of necrotizing fasciitis.

Necrotizing Fasciitis Symptoms

Early Symptoms

The early symptoms of necrotizing fasciitis may easily be mistaken for the common flu because the symptoms—such as general body aches, sore throat, nausea, diarrhea, and chills—are very similar. But with necrotizing fasciitis, there may be erythema (redness), pain, and tenderness at the site of infection on the skin.

People with necrotizing fasciitis are often in pain out of proportion to how their skin looks.

Often the infection starts at:

  • A surgical site
  • A cut or scratch
  • A bruise or boil
  • An injection site
  • A small injury

Quickly Spreading Infection

The infection spreads rapidly. Often, an infected area of the skin can spread as fast as an inch every hour.

Early symptoms of the condition include:

  • An area of the skin that is warm
  • Erythema (a reddened area of the skin)
  • Pain (the pain often radiates [spreads] beyond the area of the skin that is reddened)
  • Swelling
  • Fever

If you have early symptoms of necrotizing fasciitis, particularly if you have recently undergone surgery, experienced an injury, or have any type of illness, it’s imperative to seek immediate medical attention. 

Late Symptoms

When necrotizing fasciitis progresses to the late or advanced symptoms, a very high fever is usually involved (over 104 degrees Fahrenheit) or hypothermia (low body temperature) may occur. Dehydration can occur with constant piercing pain, and the infected skin may appear shiny, swollen, or feel hard to the touch (induration) due to swelling.

As the condition progresses, necrotizing fasciitis can cause severe symptoms, these may include:

  • Black spots on the skin
  • Skin ulcers
  • A change in skin color (including red, bronze, or violet-colored skin)
  • Oozing pus from the skin ulcer
  • The presence of large, fluid-filled blisters (a sign that the tissue may be necrotizing or dying)
  • Dizziness, confusion
  • Fatigue and weakness
  • Diarrhea
  • Nausea
  • Low blood pressure
  • Rapid heart rate

When the pain suddenly ceases—after which it has been severe—this can be a very late sign that may indicate the nerves have begun to die in the area.

At this point, severe symptoms such as confusion, weakness, and delirium may occur. A person may lose consciousness and the infected area often swells significantly and may increase several times its normal size.

The affected area may even split open, oozing large amounts of fluid. Large blisters called bullae, which are filled with bloody or yellowish fluid or blackened necrotic lesions, may appear.

Toxic Shock Syndrome

If left untreated, necrotizing fasciitis can cause toxic shock syndrome, which causes the body’s vital organs to shut down. Without treatment, the outcome is death.


While several specific underlying causes of necrotizing fasciitis have been identified, some people are much more prone to the condition, including those with a compromised immune system.

Disorders that cause immunosuppression (a compromised immune system) include:

Necrotizing fasciitis can occur in children with chickenpox, but this happens rarely.

Underlying causes of necrotizing fasciitis include bacteria entering the skin secondarily to:

  • Cuts
  • Scrapes
  • Insect bites
  • Wounds
  • IV drug use
  • Injuries that do not break the skin (such as blunt trauma)

Necrotizing fasciitis is commonly caused by a group of organisms called group A Streptococcus (GAS) bacteria. Streptococcus bacteria is the same type of bacteria that can cause a common condition called strep throat. But, in necrotizing fasciitis, several types of bacteria, including Staphylococcus and others are associated with the disorder.


The type of bacteria that can cause necrotizing fasciitis may include:

  • A Streptococcus
  • Aeromonas hydrophila
  • Clostridium
  • E. coli
  • Klebsiella
  • Staphylococcus aureus


Diagnosing necrotizing fasciitis can be difficult when symptoms are nonspecific—such as fever, pain, or edema—but time is of the essence. Sometimes the early symptoms appear much like other common infections (such as the flu or strep throat).

Diagnostic measures may include a visual examination of the affected area, as well as:

  • A biopsy and tissue culture
  • A blood sample
  • A gram stain
  • Imaging tests (a CT scan, MRI, or ultrasound of the affected area)

Surgical Exploration

Exploratory surgery is commonly employed to diagnose necrotizing fasciitis. The surgeon looks for:

  • Foul-smelling discharge
  • Necrosis (death of tissue)
  • Lack of bleeding

Another finding includes the lack of resistance of the fascia. These signs are often definitive for a diagnosis. 

When necrotizing fasciitis is suspected, the diagnostician may not wait for the lab results before starting treatment; early diagnosis and intervention are imperative to improving the survival rate for people with necrotizing fasciitis.


The treatment of necrotizing fasciitis depends on the stage of the disease, complications (such as toxic shock), and more. Standard treatment of necrotizing fasciitis may include:

  • Surgical debridement: A surgical procedure to remove dead, damaged, infected tissue. Studies have shown that the timing and effectiveness of the initial debridement procedure have the biggest impact on survival rates.
  • Antibiotic medication administration: Using broad-spectrum antibiotics is very important in the treatment of necrotizing fasciitis.
  • Hyperbaric oxygen therapy: A treatment aimed at boosting the body’s natural healing processes, hyperbaric oxygen therapy is also thought to inhibit toxin production.
  • IV (intravenous) globulin (IVIg) therapy: A type of therapy that combines antibiotics with immune factors, immune globulins are proteins used by the immune system to fight bacteria and viruses.


Because there is no vaccine to prevent group A strep infections (including necrotizing fasciitis), and because the prognosis of necrotizing fasciitis is poor, prevention measures are very important.

Steps that you can take to prevent the condition include:

  • Performing effective wound care including washing minor cuts, abrasions, and other injuries with soap and water
  • Cleaning wounds, cover open or draining wounds with clean, dry bandages (use an antibiotic ointment as instructed by your healthcare provider, to prevent infection)
  • For deep, puncture wounds or serious injuries, consult with your healthcare provider, prophylactic (preventative) antibiotics may be prescribed
  • Performing good handwashing techniques
  • Using an alcohol-based hand cleanser when hand washing is not possible
  • Properly care for fungal infections (such as athlete’s foot) according to your healthcare provider’s instructions. 

In addition to performing good wound care and proper handwashing techniques, other preventative measures should be taken (particularly when you have open wounds) such as avoiding bodies of water.

What to Avoid

If you have an open wound avoid:

  • Hot tubs
  • Swimming pools
  • Swimming in lakes, rivers, or oceans


The mortality rate for a person who is diagnosed with necrotizing fasciitis ranges from 24% to 34%. When a person develops complications (such as toxic shock), the mortality rate increases to 60%.


It’s important to educate yourself on aspects of the disease such as treatment options. If you are unsure about your plan of treatment, get a second opinion.

Also, reach out for emotional support. This includes talking to close friends and family members as well as employing professional help when needed, such as participating in group or individual therapy and/or support groups).

Reaching out to others who are going through similar circumstances can make a huge difference in a person’s overall outlook and subsequently lend itself to recovery. Organizations such as the Necrotizing Fasciitis Foundation can point you in the right direction.

7 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Johns Hopkins Medicine. Muscle pain: it may actually be your fascia.

  2. Centers for Disease Control and Prevention. Type II necrotizing fasciitis.

  3. DermNet NZ. What is necrotizing fasciitis?

  4. National Organization of Rare Diseases (NORD). Necrotizing fasciitis.

  5. Centers for Disease Control and Prevention. Necrotizing fasciitis: all you need to know

  6. Wu L, Chung KC, Waljee JF, Momoh AO, Zhong L, Sears ED. A national study of the impact of initial débridement timing on outcomes for patients with deep sternal wound infection. Plastic and Reconstructive Surgery. 2016;137(2):414e-423e. doi:10.1097/01.prs.0000475785.14328.b2

  7. Centers for Disease Control and Prevention. Group A streptococcal (GAS) disease.

By Sherry Christiansen
Sherry Christiansen is a medical writer with a healthcare background. She has worked in the hospital setting and collaborated on Alzheimer's research.