Gangrene is death of body tissue due to a lack of blood flow or a serious bacterial infection. Gangrene commonly affects the arms and legs, including the toes and fingers, but it can also occur in the muscles and in organs inside the body, such as the gallbladder.

Your risk of gangrene is higher if you have an underlying condition that can damage your blood vessels and affect blood flow, such as diabetes or hardened arteries (atherosclerosis).

Treatments for gangrene include surgery to restore blood flow and remove dead tissue, antibiotics if there is an infection, and hyperbaric oxygen therapy. The earlier gangrene is identified and treated, the better your chances for recovery.

When gangrene affects your skin, signs and symptoms may include:

• Skin discoloration — ranging from pale to blue, purple, black, bronze or red, depending on the type of gangrene you have
• Swelling
• Blisters
• Sudden, severe pain followed by a feeling of numbness
• A foul-smelling discharge leaking from a sore
• Thin, shiny skin, or skin without hair
• Skin that feels cool or cold to the touch

If you have a type of gangrene that affects tissues beneath the surface of your skin, such as gas gangrene or internal gangrene, you may also have a low-grade fever and generally feel unwell.

If the germs that caused the gangrene spread through your body, septic shock can occur. Signs and symptoms of septic shock include:

• Low blood pressure
• Fever, although some people may have a body temperature lower than the normal 98.6 F (37 C)
• Rapid heart rate
• Lightheadedness
• Shortness of breath
• Confusion

When to see a doctor

Gangrene is a serious condition and needs emergency treatment. Call your doctor right away if you have persistent, unexplained pain in any area of your body along with one or more of the following signs and symptoms:

• Persistent fever
• Skin changes — including discoloration, warmth, swelling, blisters or lesions — that won't go away
• A foul-smelling discharge leaking from a sore
• Sudden pain at the site of a recent surgery or trauma
• Skin that's pale, hard, cold and numb

Causes of gangrene include:

• Lack of blood supply. Your blood provides oxygen and nutrients to your body. It also provides your immune system with antibodies to ward off infections. Without a proper blood supply, your cells can't survive, and your tissue decays.
• Infection. An untreated bacterial infection can cause gangrene.
• Traumatic injury. Gunshot wounds or crushing injuries from car crashes can cause open wounds that let bacteria into the body. If the bacteria infect tissues and remain untreated, gangrene can occur.

Types of gangrene

• Dry gangrene. This type of gangrene involves dry and shriveled skin that looks brown to purplish blue or black. Dry gangrene may develop slowly. It occurs most commonly in people who have diabetes or blood vessel disease, such as atherosclerosis.

• Wet gangrene. Gangrene is referred to as wet if there's a bacterial infection in the affected tissue. Swelling, blistering and a wet appearance are common features of wet gangrene.

  Wet gangrene may develop after a severe burn, frostbite or injury. It often occurs in people with diabetes who unknowingly injure a toe or foot. Wet gangrene needs to be treated immediately because it spreads quickly and can be deadly.

• Gas gangrene. Gas gangrene typically affects deep muscle tissue. If you have gas gangrene, the surface of your skin may look normal at first.

  As the condition worsens, your skin may become pale and then turn gray or purplish red. The skin may look bubbly and may make a crackling sound when you press on it because of the gas within the tissue.

  Gas gangrene is most commonly caused by infection with a bacterium called Clostridium perfringens. Bacteria gather in an injury or surgical wound that has no blood supply. The bacterial infection produces toxins that release gas and cause tissue death. Like wet gangrene, gas gangrene is a life-threatening condition.

• Internal gangrene. Gangrene that affects one or more of your organs, such as your intestines, gallbladder or appendix, is called internal gangrene. This type of gangrene occurs when blood flow to an internal organ is blocked — for example, when your intestines bulge through a weakened area of muscle in your stomach area (hernia) and become twisted.

  Left untreated, internal gangrene can be deadly.

• Fournier's gangrene. Fournier's gangrene involves the genital organs. Men are more often affected, but women also can develop this type of gangrene. An infection in the genital area or urinary tract causes this type of gangrene.
• Meleney's gangrene. This rare type of gangrene — also called progressive bacterial synergistic gangrene — is usually a complication of surgery. People with Meleney's gangrene develop painful skin lesions one to two weeks after their operations.

Several factors increase your risk of developing gangrene. These include:

• Diabetes. If you have diabetes, your body doesn't produce enough of the hormone insulin (which helps your cells take up blood sugar) or is resistant to the effects of insulin. High blood sugar levels can eventually damage blood vessels, decreasing or interrupting blood flow to a part of your body.
• Blood vessel disease. Hardened and narrowed arteries (atherosclerosis) and blood clots also can block blood flow to an area of your body.
• Severe injury or surgery. Any process that causes trauma to your skin and underlying tissue, including an injury or frostbite, increases your risk of developing gangrene, especially if you have an underlying condition that affects blood flow to the injured area.
• Smoking. People who smoke have a higher risk of gangrene.
• Obesity. Obesity often accompanies diabetes and vascular disease, but the stress of extra weight alone can also compress arteries, leading to reduced blood flow and increasing your risk of infection and poor wound healing.
• Immunosuppression. If you have an infection with the human immunodeficiency virus (HIV) or if you're undergoing chemotherapy or radiation therapy, your body's ability to fight off an infection is impaired.
• Medications or drugs that are injected. In rare instances, certain medications and illegal drugs that are injected have been shown to cause infection with bacteria that cause gangrene.
• Complications of COVID-19. There have been a few reports of people getting dry gangrene in their fingers and toes after having COVID-19-related blood clotting problems (coagulopathy). More research is needed to confirm this association.

Gangrene can lead to serious complications if it's not immediately treated. Bacteria can spread quickly to other tissues and organs. You may need to have a body part removed (amputated) to save your life.

Removal of infected tissue can lead to scarring or the need for reconstructive surgery.

Here are a few suggestions to help you reduce your risk of developing gangrene:

• Care for your diabetes. If you have diabetes, make sure you examine your hands and feet daily for cuts, sores, and signs of infection, such as redness, swelling or drainage. Ask your doctor to examine your hands and feet at least once a year, and try to maintain control over your blood sugar levels.
• Lose weight. Excess pounds not only put you at risk of diabetes but also place pressure on your arteries, constricting blood flow and putting you at risk of infection and slow wound healing.
• Don't use tobacco. The chronic use of tobacco products can damage your blood vessels.
• Help prevent infections. Wash any open wounds with a mild soap and water and try to keep them clean and dry until they heal.
• Watch out when the temperature drops. Frostbitten skin can lead to gangrene because frostbite reduces blood circulation in an affected area. If you notice that any area of your skin has become pale, hard, cold and numb after prolonged exposure to cold temperatures, call your doctor.

Tests used to help make a diagnosis of gangrene include:

• Blood tests. An abnormally high white blood cell count is usually a sign of infection. Your doctor might also order blood tests to look for the presence of specific bacteria or other germs.
• Fluid or tissue culture. Tests of the fluid from a blister on your skin may be examined for bacteria that can cause gangrene. Your doctor may look at a tissue sample under a microscope for signs of cell death.
• Imaging tests. X-rays, computerized tomography (CT) scans and magnetic resonance imaging (MRI) scans can show your organs, blood vessels and bones. Your doctor can use the results of these tests to determine how far the gangrene has spread throughout your body.
• Surgery. Surgery may be done to get a better look inside the body and learn how much tissue is infected.

Tissue that has been damaged by gangrene can't be saved, but steps can be taken to prevent gangrene from getting worse. The faster you get treatment, the better your chance for recovery.

Treatment for gangrene may involve medication, surgery or hyperbaric oxygen therapy — or a combination of these therapies — depending on the severity of your condition.

Medications

Medications to treat a bacterial infection (antibiotics) are given through an IV or taken by mouth.

Pain medications may be given to relieve your discomfort.

Surgery or other procedures

Depending on the type of gangrene you have and its severity, you may need more than one surgery. Surgery for gangrene includes:

• Debridement. This type of surgery is done to remove the infected tissue and stop the infection from spreading. Your doctor may also perform surgery to repair any damaged or diseased blood vessels to restore blood flow to the infected area. Your doctor may prescribe certain antibiotics until the infection is cleared.
• Amputation. In severe cases of gangrene, the infected body part — such as a toe, finger, arm or leg — may need to be surgically removed (amputated). You may later be fitted with an artificial limb (prosthesis).
• Skin grafting (reconstructive surgery). Sometimes, surgery is needed to repair damaged skin or to improve the appearance of gangrene-related scars. Such surgery may be done using a skin graft. During a skin graft, your doctor removes healthy skin from another part of your body — usually a place hidden by your clothing — and carefully spreads it over an affected area. The healthy skin may be held in place by a dressing or by a couple of small stitches. A skin graft can be done only if there is enough blood supply to the area.

Hyperbaric oxygen therapy

Hyperbaric oxygen therapy is done inside a chamber pressurized with pure oxygen. You usually lie on a padded table that slides into a clear plastic tube. The pressure inside the chamber will slowly rise to about 2.5 times normal atmospheric pressure.

When you're safely exposed to increased pressure and oxygen, your blood can carry more oxygen. Oxygen-rich blood slows the growth of bacteria that live in tissue lacking oxygen and helps infected wounds heal more easily.

The treatment for gangrene generally lasts about 90 minutes. You may need two to three treatments every day until the infection clears.

Call your doctor right away if you have symptoms of gangrene. Depending on the severity of your symptoms, you may be told to go to the emergency room or to call 911 or your local emergency number for medical help.

If you have time before you leave home or on the way to the hospital, use the information below to get ready for your medical evaluation.

What you can do

• Write down any symptoms you've been experiencing and for how long. It will help your doctor to have as many details as possible about when your symptoms first appeared and how they may have worsened or spread over time.
• Write down any recent injury or trauma to your skin, including cuts, bites, injections, surgery or possible frostbite. If you have recently used injectable recreational drugs, this is critical information to share with your doctor.
• Write down your key medical information, including any other conditions with which you've been diagnosed. Also write down all medications, vitamins or supplements that you're taking.
• Take a family member or friend along. Gangrene is a medical emergency. Take someone with you to help you remember all the information your doctor provides. You'll also want someone who can stay with you if you need immediate treatment.
• Write down questions to ask your doctor.

For gangrene, some basic questions to ask your doctor include:

• What's the most likely cause of my symptoms or condition?
• What kinds of tests do I need?
• Do I need to be hospitalized?
• What treatments do I need?
• How soon do you expect my symptoms to improve with treatment?
• Will I have a full recovery? If so, how long will recovery take?
• Am I at risk of long-term complications?

Don't hesitate to ask your doctor any additional questions you have.

What to expect from your doctor

Your doctor is likely to ask you several questions to help determine the next steps in making your diagnosis and starting care. Your doctor may ask:

• What are your symptoms?
• When did you first begin experiencing symptoms?
• How painful is the affected area?
• Do your symptoms seem to be spreading or getting worse?
• Have you had any recent injuries or trauma to your skin, such as cuts, wounds, bites or surgery?
• Have you recently had any prolonged exposure to extreme cold that made your skin change color or turn numb?
• Do you use injectable drugs, including recreational drugs?
• Have you been diagnosed with any other medical conditions?
• What medications are you taking or have recently taken, including prescription drugs, over-the-counter medications, herbs and supplements?