Let’s Talk About Cellulitis Causes

This bacterial skin infection can be dangerous. Here’s how it happens and how to avoid it.

by Denise Mann Health Writer

Your doctor just told you that the red circle on your lower leg is called cellulitis—and it is likely the reason you have been feeling under the weather lately. You’ve started taking an antibiotic and your doc says you’ll be back to normal in no time. But how did you get here? You don’t remember getting cut or injured, so why did you wind up with a serious bacterial infection? Here, we break down the causes of cellulitis.

Cellulitis Causes

Our Pro Panel

We went to some of the nation’s top cellulitis experts to bring you the most scientific and up-to-date information possible.

Gina A. Suh, M.D. headshot.

Gina A. Suh, M.D.

Infectious Diseases Specialist

Mayo Clinic

Rochester, MN

Jun Kevin Kang, M.D. headshot.

Jun Kevin Kang, M.D.

Assistant Professor of Dermatology

Johns Hopkins Medicine

Baltimore, MD

Ohara Aivaz, M.D. headshot.

Ohara Aivaz, M.D.


Cedars-Sinai Dermatology

Los Angeles, CA

Cellulitis Causes
Frequently Asked Questions
Can diabetes cause cellulitis?

While diabetes doesn’t cause cellulitis per se, it can increase your chances of developing it. Nerve damage that results from diabetes can make it difficult to feel your feet, and this means you may miss a cut that then gets infected.

How does lymphedema cause cellulitis?

Your lymph system transports infection-fighting white blood cells through your bloodstream so they can get where they are needed. When they are blocked by lymphedema, these cells can’t do their job and, as a result, you are at higher risk for infections like cellulitis.

What type of skin injuries cause cellulitis?

Name a skin injury, and chances are it can cause cellulitis if you are vulnerable. Common culprits include shaving nicks, animal bites, bug bites, IV drug use, tattoos, and body piercing. Anything that leads to a break in your skin can potentially allow bacteria to enter.

How is cellulitis treated?

The good news is that cellulitis is highly treated, usually with a course of antibiotics. When caught early, you can take these orally, but if your infection has spread, you may need to receive antibiotics intravenously in the hospital.

Remind Me, What Is Cellulitis?

Cellulitis is a common bacterial skin infection that affects the deeper layers of your skin. Symptoms include redness, swelling, and pain in the affected area, most typically on a lower leg or foot. Streptococcus (strep) and Staphylococcus (staph) are the usual culprits, but MRSA (methicillin-resistant Staph aureus) and other bacteria may also cause cellulitis.

Cellulitis can bring on bouts of fever, nausea, and other systemic symptoms. Things start to get dicey if and when the infection starts to spread to other parts of your body or bloodstream, where it can wreak havoc on your blood, joints, bone, and/or the lining of the chambers of your heart and heart valves (an infection known as endocarditis).

It can also cause your veins themselves to swell if the infection leads to blood clots that form close to the skin. In rare cases, cellulitis also may lead to necrotizing fasciitis, or flesh-eating disease. This is a medical emergency, but fortunately the odds of this occurring are super slim, especially if you start treatment for cellulitis right away.

Antibiotics can usually knock out the infection, especially when started early. But despite the success in treating cellulitis, it’s important to know what caused it in the first place. Let’s dive into that now.

Get the Basics (and So Much More) About Cellulitis

What Causes Cellulitis?

The list of potential causes of cellulitis is long and has a lot to do with your overall health and well-being. In a nutshell, cellulitis develops when bacteria enter your skin via an open cut or wound. Here’s how that might happen:

  • Microscopic nick: Even cuts that you don’t remember getting or you thought were inconsequential (slicing your finger while making a salad) can leave a wound through which bacteria enter.

  • Bodywork: Getting a tattoo or body piercing, especially if the operation was less than hygienic despite its 4-star reviews, can introduce bacteria.

  • IV drug use: Dirty needles can provide another portal of entry for bacteria, as can bug or animal bites.

  • Blisters: Sores from chickenpox and shingles can become infected and result in cellulitis.

Risk Factors of Cellulitis

Not everyone will develop cellulitis from a cut or wound, as your immune system often attacks the bacteria before it can do any harm. So, why you? Good question. There are many potential answers, ranging from pre-existing health conditions that make you more vulnerable to infection to life-saving surgery and even lifestyle habits. Here are the most important causes to be aware of so that you can better protect yourself.

Compromised Immune System

When your immune system is weakened, it doesn’t have the power to prevent bacteria from entering your body through cuts. Your immune system may become compromised for a host of reasons, including underlying conditions like HIV/AIDS, medications such as chemotherapy to treat cancer, or drugs that prevent your body from rejecting transplanted organs. Drinking too much alcohol can also lower your body’s ability to fight off infection.

No matter how small, clean all wounds well using soap and water, apply antibacterial ointment, and keep them covered with a bandage until they heal. Avoid hot tubs, pools, rivers, lakes, and other bodies of water when you have an open cut, as these can be breeding grounds for bacteria. If you’re managing a condition that affects your immune system, check in with your medical team to see what other proactive steps you should be taking.


This is a biggie when it comes to potential cellulitis causes. When you have diabetes, you can develop nerve damage that prevents you from actually feeling cuts and wounds, especially those on your feet. And if you can’t feel them, it’s hard to clean them and stave off infection. What’s more, high blood sugar levels associated with the condition feed bacteria and allow them to multiply. It’s really the perfect storm for cellulitis.

If you have diabetes, check your feet daily, examining them closely with the help of a hand mirror if needed. Schedule a yearly (or more often if recommended) podiatrist visit and be sure to keep the appointment. If you find a cut, clean it well to prevent infection.

Also, keep your blood sugar as tightly controlled as possible. This will help reduce the risk of cellulitis as well as other potential consequences of diabetes, including heart disease, kidney disease, and vision problems. Your endocrinologist can help if testing is a challenge for you or your numbers fluctuate.


Lymphedema is a chronic condition that is also common cause of cellulitis. It occurs when your lymph system, which normally transports infection-fighting white blood cells throughout your body, has a blockage. Suddenly, traffic comes to a standstill and causes a painful buildup of lymph fluid in an arm or leg. As your body begins to swell, your skin barrier is compromised and your risk of cellulitis rises.

You may develop lymphedema after cancer surgery to remove lymph nodes, after radiation, or as a result of some genetic conditions. In truth, anything that causes your arms and legs to swell may cause cellulitis.

If you have lymphedema, take extra care of your skin to prevent injuries. Shave with an electric razor rather than a manual one to lower your chances of nicks, and wear gloves when cooking, cleaning, or working in your garden. Always have blood drawn in your unaffected arm; the same goes for shots, including vaccines. Compression hose or leg and arm wrappings can also reduce swelling, so ask your doctor for recommendations for products and guidelines on when to wear them. Keeping the affected limb elevated also helps with any pain and swelling, and less swelling allows for better transportation of white blood cells.

Athlete’s Foot

Surprised? This nuisance of a condition can be a contributor to cellulitis because the flaky, itchy skin on the soles of your feet and in between your toes can tear. If bacteria find their way in, you may find yourself back at the doctor’s office for another course of antibiotics for cellulitis.

To prevent cellulitis, treat your athlete’s foot thoroughly. Medications are available to kill the fungus that causes this condition. Once it’s gone, keep it from coming back by making sure your feet remain clean and dry and that your toenails are short. Always wear flip-flops or shoes when walking around pools, gyms, showers, or locker rooms—common sites of transmission—so that you don’t pick it up again.


With this chronic disease, your skin is unable to form as robust a barrier against bacteria. Plus dryness, a hallmark of eczema, can lead to cracks. To make matters worse, the itch of eczema can be nearly intolerable and anytime you scratch your itch, bacteria from under your nail will make its move, targeting openings in your skin and setting the stage for cellulitis.

Avoiding eczema flares is your best bet for preventing cellulitis, and you can do that by moisturizing daily and minimizing exposure to your triggers. There are also medications to help keep your eczema under better control. Fewer flares mean less itching and scratching, which closes the window of opportunity for bacteria to enter.

Weight Issues

Being overweight or obese sets you up for a host of diseases and conditions, including cellulitis. It leads to poor circulation in your arms, legs, hands, or feet, which can cause swelling and skin stretching, leading to cracks or tears that allow bacteria to enter the deeper layers of your skin. Obesity is also a major risk factor for diabetes, and that is yet another risk for developing cellulitis.

Losing weight and keeping it off can help lower your chances of developing cellulitis and set you on a healthier path from head to toe. Talk to your doctor or a registered dietitian about the best ways to lose weight—and keep in mind that the most effective diets are the ones you can stick with indefinitely.

Heart Surgery

If you have had the type of heart surgery known as coronary artery bypass grafting, you are now at higher risk of cellulitis. This technique involves the removal of a vein from your leg and its use as the connector to your coronary artery. It’s designed to boost blood flow to your heart, but while it can be lifesaving, the surgery may also cause leg swelling, thus raising your risk of getting cellulitis.

Let’s face it: If you need heart surgery, you need heart surgery—not much you can do there. Your best cellulitis prevention tip is to take extra-good care of your skin to prevent infection. Take steps to clean any cuts, even minor ones, with soap and water and apply an antibiotic ointment daily. Keep the surgical area covered with a bandage until your leg heals. Stay out of pools, hot tubs, or other waterways if you have an open cut, as these are places that bacteria tend to lurk.

Tattoo or Piercing

Pretty much anything that causes a tear in your skin can let bacteria in, and tattoos or piercings, especially if they are done in less-than-hygienic settings, are potential culprits.
Do your best to choose a clean and reputable salon for your body work. Make sure any jewelry used in the piercing is sterilized first. It’s also critical that the operator thoroughly cleans your skin before the procedure and that you carefully follow your aftercare instructions.

The bottom line: If your immune system isn’t working as well as it should be and you get a cut or tear in your skin, you could develop cellulitis. Once you have had cellulitis, you are more likely to get it again. The best way to prevent repeat bouts is to understand why you got it in the first place and take steps to minimize any risks.

Denise Mann
Meet Our Writer
Denise Mann

Denise Mann, MS is a veteran freelance health writer in New York. Her work has appeared on HealthDay, among other outlets. She was awarded the 2004 and 2011 journalistic Achievement Award from the American Society for Aesthetic Plastic Surgery. She was also named the 2011 National Newsmaker of the Year by the Community Anti-Drug Coalitions of America. She's also been awarded the Arthritis Foundation's Northeast Region Prize for Online Journalism, the Excellence in Women's Health Research Journalism Award, the Gold Award for Best Service Journalism from the Magazine Association of the Southeast, a Bronze Award from The American Society of Healthcare Publication Editors, and an honorable mention in the International Osteoporosis Foundation Journalism Awards. She was part of the writing team awarded a 2008 Sigma Delta Chi award for her part in a WebMD series on autism. Mann has a graduate degree from the Medill School of Journalism at Northwestern University in Evanston, Ill.