The phrase “flesh-eating bacteria” refers to a rare but potentially life-threatening infection, which affects the skin and soft tissues down to the muscles. The medical term for a flesh-eating bacterial infection is necrotizing fasciitis (NF) 234. With this condition, the bacteria enter through a skin wound, which may be as innocuous as a minor cut or bug bite. The bacteria multiply rapidly and spread to the surrounding tissues. The hallmarks of NF are the death of the affected tissues, causing an expanding, deep, open wound, and the rapidly advancing spread of the infection. Recognizing the early signs of NF can lead to early diagnosis and treatment of this disfiguring and potentially deadly infection.

Is This an Emergency?

If you are experiencing serious medical symptoms, seek emergency treatment immediately.


Fever may be the first recognized sign of necrotizing fasciitis 24. In the early hours of the infection, a fierce battle between the invading bacteria and the body’s immune system rages under the skin surface of the affected area. During this phase of the infection, both the bacteria and the immune system produce substances that cause fever, often accompanied by chills.

Skin Redness and Heat

Early on, the area involved in NF is literally red hot--the skin is red in color and hot to the touch. The intensity of both the color and the temperature of the skin exceed what would normally be expected with an uncomplicated skin wound. In addition, the redness and heat advance outward from the original wound rapidly; noticeable changes from one hour to the next are the norm.

Excessive Pain

An important early warning sign of NF is pain that exceeds the apparent level of injury. The area affected by an evolving case of NF is usually painful without being touched and is exquisitely tender when touched.


An area of developing NF swells markedly and quickly. In addition, the swelling advances outwardly at a rapid rate. With intense swelling, the skin is taut and the area feels hard when touched.

Elevated White Blood Cell Count

An elevated white blood cell count is a common early sign of NF. As the body’s immune system responds to the bacterial invasion, it signals the bone marrow to release additional white blood cells to join the effort to overcome the advancing infection. This manifests with an elevated white blood cell count.


Tachycardia -- an abnormally high heart rate -- is a common early sign of NF. This sign may be related to the presence of fever or serve as an indicator of impending shock due to overwhelming infection.


People with early NF feel and appear unwell. Their degree of illness typically seems disproportionately severe relative to their physical signs and symptoms. This finding should raise suspicion for possible NF when a skin wound is present.


If you experience any signs or symptoms of necrotizing fasciitis, seek immediate medical attention 234. This potentially life-threatening infection progresses quickly. Early treatment is essential to surviving this condition and limiting the amount of tissue damage.