People with obesity have a higher risk of a rare but life-threatening bacterial skin infection called necrotizing fasciitis. As the body’s largest organ, your skin is influenced by your overall health. Obesity can cause skin conditions and other health problems that may increase the likelihood of getting necrotizing fasciitis. This article looks at how obesity and skin folds can affect that risk.

What Is Necrotizing Fasciitis?

Necrotizing fasciitis is a fast-moving infection that damages the skin and the soft tissues underneath. The name explains the condition: “Necrotizing” refers to tissue death, and “fasciitis” refers to inflammation of the fascia — the connective tissue that supports muscles and organs.

Necrotizing fasciitis usually starts in the layer of fascia under the skin, called the subcutaneous fascia. You might hear necrotizing fasciitis called a flesh-eating disease because of the way it kills the infected tissue.

Causes of Necrotizing Fasciitis

Necrotizing fasciitis happens when bacteria (germs) infect the skin and fascia. In most cases, the bacteria enter through a break in the skin. Less commonly, a trauma that doesn’t cause an open sore or cut can lead to necrotizing fasciitis. As the infection spreads, it blocks off blood vessels that supply the skin with nutrients and oxygen, and the affected tissue begins to die.

Necrotizing fasciitis can be monomicrobial (caused by a single type of bacteria, most commonly Group A streptococcus or Staphylococcus aureus) or polymicrobial (involving a mix of types). A fungal infection can also cause necrotizing fasciitis, especially in people who have trauma wounds and a weakened immune system.

Symptoms of Necrotizing Fasciitis

Necrotizing fasciitis moves quickly. Symptoms often get worse over just a few days and can become serious fast.

Initial Symptoms

Most people notice symptoms within 24 hours of an injury. The first symptom is typically severe pain that gets worse with time. Some people also develop flu-like symptoms, such as:

• Fever
• Chills
• Diarrhea
• Nausea
• Dizziness
• Body aches
• Dehydration

Skin Changes

Because the infection starts deep, the skin surface may look normal at first. However, after three to four days, changes usually appear in the area. These symptoms include:

• Erythema (red or purple discoloration)
• Blisters filled with dark or yellow fluid
• Blackened areas around the wound
• A crackling sensation under the skin from gas bubbles
• Swelling

Later Symptoms

By about the fifth day, necrotizing fasciitis can cause serious illness, including:

• Sepsis (a dangerous immune response that can lead to organ failure)
• A bloodstream infection
• Low blood pressure

Obesity’s Effect on the Risk of Necrotizing Fasciitis

Necrotizing fasciitis can happen to anyone — young, otherwise healthy people make up about half of all cases. However, people with obesity have an increased risk because they may be more likely to have risk factors such as certain comorbidities (coexisting conditions) and skin changes.

Diabetes

People with overweight or obesity are more likely to have type 2 diabetes, which is a major risk factor for necrotizing fasciitis — especially the polymicrobial kind. Studies have shown that about 45 percent to 72 percent of people with necrotizing fasciitis also have diabetes.

Leg and foot ulcers (open sores) are a common complication of diabetes. These ulcers may heal slowly, providing an entry point for bacteria that cause necrotizing fasciitis. Diabetes can also weaken the immune system, making it harder to fight off infections. People with diabetes may also face worse outcomes from necrotizing fasciitis compared to those without diabetes and are more likely to need amputation (surgical removal of a limb).

Some people with diabetes take a newer group of medications called SGLT2 inhibitors, which help the body get rid of extra sugar through urine. Although these drugs help protect the heart and kidneys, a rare and serious side effect is Fournier’s gangrene — a type of necrotizing fasciitis that affects the genitals or perineum (the area between the genitals and anus). The risk of this life-threatening condition is higher in older men with poorly controlled diabetes.

Liver Problems

Cirrhosis (late-stage liver disease) can raise the risk of necrotizing fasciitis. Obesity is a risk factor for metabolic dysfunction-associated steatotic liver disease (MASLD), a liver disease that can lead to cirrhosis. People with liver disease may also be more likely to get necrotizing fasciitis if they eat raw seafood, which can carry harmful bacteria.

Skin Folds

Increased body weight can create larger skin folds in areas such as:

• The neck
• Armpits
• The groin
• Under the breasts

Friction from the skin rubbing together and increased sweating in skin folds can cause an inflammatory skin condition called intertrigo. The warm, dark, and moist conditions in skin folds are ideal for bacterial growth. If the skin is inflamed or damaged due to intertrigo, a bacterial skin infection can turn into necrotizing fasciitis.

Lymphedema

Lymphedema is swelling caused by problems with the lymphatic system. Obesity can lead to lymphedema if adipose (fat) tissue blocks normal drainage of fluid in tissues. People with lymphedema are more likely to get infections like cellulitis — a bacterial infection that affects the skin and subcutaneous tissues (the layer beneath the skin). Although rare, necrotizing fasciitis has also been reported.

Chronic Venous Insufficiency

Chronic venous insufficiency occurs when damaged veins in the legs don’t return blood properly. This condition is common in people with obesity and can lead to ulcers on the lower legs and ankles. These sores can provide an entrance for bacteria that cause necrotizing fasciitis.

Pressure Ulcers

Also called bedsores, pressure ulcers are open wounds that form when you stay in the same position for a long time, which places pressure on one area of the skin. Pressure ulcers usually develop in bony areas such as the hips, ankles, and base of the spine. People with obesity who have trouble moving regularly may be at risk. If untreated, pressure sores may become infected and lead to necrotizing fasciitis.

Other Risk Factors

Some risk factors for necrotizing fasciitis aren’t directly related to obesity. These include:

• Older age
• Alcohol use disorder
• Pregnancy
• Immune system dysfunction
• Poor blood circulation
• Cancer
• Injection drug use
• Injuries from marine animals
• Consumption of raw seafood

Treatment of Necrotizing Fasciitis

The main treatment for necrotizing fasciitis involves surgery to remove the infected and dead tissue. Some cases require more than one surgery to completely resolve the infection. Your doctor may also prescribe antibiotics to help fight bacteria and prevent new infections.

Prevention of Necrotizing Fasciitis

It may not always be possible to prevent necrotizing fasciitis and other skin infections. Necrotizing fasciitis develops quickly. If you notice any signs of infection, it’s important to seek medical care right away.

Managing chronic (long-term) health conditions, such as diabetes and liver disease, can help lower your risk of necrotizing fasciitis. If you have diabetes, talk to your healthcare providers about how to manage your blood glucose (sugar) levels to avoid ulcers and other complications.

Proper skin care may also help prevent problems that can lead to ulcers. These tips can help you keep your skin dry, reduce friction, and avoid serious complications:

• Gently pat skin dry — don’t rub — with a clean towel.
• Use a fan or hair dryer on the cool setting to dry between skin folds.
• Avoid tight clothing.
• Apply a barrier cream in areas with skin folds.

You can also ask your healthcare provider whether weight loss may help improve skin health and reduce the risk of infections linked to obesity.

Talk With Others Who Understand

MyObesityTeam is the social network for people with obesity and their loved ones. On MyObesityTeam, more than 57,000 members come together to ask questions, give advice, and share their stories with others who understand life with obesity.

Have you had necrotizing fasciitis or other skin problems related to obesity or skin folds? Have you discussed your risk of skin problems with your healthcare provider? Share your comments below, start a conversation by posting on your Activities page, or connect with like-minded members in Groups.