Cellulitis is a potentially serious bacterial infection that develops in the deep layers of the skin, below the epidermis. It can get worse quickly, so if you develop signs or symptoms of cellulitis, you should see a doctor right away.
Signs and symptoms of cellulitis include swelling, redness, pain, and tenderness in the affected area. Some people also develop blisters, chills, fevers, and nausea. (1)
Cellulitis is treatable with antibiotics. But if it goes untreated, the infection can get into the bloodstream and become life-threatening.
Even though cellulitis isn’t always preventable, understanding its causes and risk factors may lower your risk of this infection.
Common Causes of Cellulitis
The two types of bacteria that cause most cases of cellulitis are Staphylococcus (staph) and Streptococcus (strep). Both can live harmlessly on intact skin, but when the skin is broken, the result can be a bacterial infection of the top or deeper layers of the skin. (2)
The strep bacterium is the same one that causes strep throat, and in rare cases, cellulitis occurs as a complication of strep throat, according to an article published in the journal American Family Physician. (3)
More commonly, cellulitis starts with a minor scratch, cut, abrasion, bug bite, or another skin injury. Taking care of these injuries promptly can prevent infection and the development of cellulitis. (4)
“Wounds should be cleaned with soap and water, covered with a thin layer of an antibiotic ointment, and then covered with a bandage,” says Amesh A. Adalja, MD, a board-certified infectious disease physician in Pittsburgh and a senior scholar and assistant professor at the Johns Hopkins University Center for Health Security in Baltimore.
“People with wounds should avoid exposure to fresh water, dirt, and the like, and wounds should be inspected daily to check for signs of infection, which could include redness, drainage, and swelling,” Dr. Adalja adds.
Most skin injuries heal best when they are covered with gauze or an adhesive bandage that keeps the wound surface moist, but not wet. (5) Change the bandage daily after examining the wound for signs of infection — or more frequently if the bandage gets dirty.
While many wounds can be treated at home, see a doctor for deeper injuries, particularly those that won’t stop bleeding, or if you believe you might need stitches.
People with diabetes, in particular, should see a doctor if they don’t see signs of wound healing within a day or two.
Risk Factors for Cellulitis
Most people will have many minor skin injuries over their lifetimes and never develop a skin infection. Yet others may develop repeated skin infections after equally minor injuries. Why is this?
Certain conditions raise the risk of developing cellulitis and other skin infections. Those conditions include having a weakened immune system, having a history of cellulitis or other skin problems (such as psoriasis or eczema), being obese or overweight, lymphedema, and use of illicit injectable drugs.
Weak Immune System
Some people develop infections easily because their immune systems aren’t strong enough to protect them from bacteria and other germs.
“A weakened immune system makes the task of invading bacteria easier, as it has less of a burden to contend with when it invades tissues,” explains Adalja.
Children and the elderly typically have weaker immune systems and thus are at greater risk of cellulitis than young and middle-aged adults.
A number of medical conditions also weaken the immune system. These include diabetes, cancer, HIV, and AIDS. You may also have a weaker immune system if you have kidney or liver disease or if you’ve recently had surgery. (2)
An autoimmune disease — such as lupus or rheumatoid arthritis — can also weaken the immune system. This not only makes you vulnerable to cellulitis, but also to other infections, such colds and the flu.
Taking an immunosuppressant drug to treat an autoimmune disease or any other disease also lowers your body’s ability to fight off invaders. (2) Corticosteroid drugs can have a similar effect.
History of Skin Problems
Cellulitis can occur as a complication of impetigo, a bacterial skin infection of the top layer of skin.
Impetigo is also commonly caused by the staph or strep bacteria. People with impetigo typically develop small bumps or blisters that rupture and form crusty scabs. Treatment for impetigo involves taking antibiotics. (6)
You can also get cellulitis when another skin condition causes a break in your skin. Such conditions include athlete’s foot, contact dermatitis, atopic dermatitis, shingles, and chickenpox.
Having one bout of cellulitis increases your chances of another infection. (1) In fact, some people deal with multiple infections in a year. In some cases, a doctor may recommend a continuous, low-dose antibiotic to prevent recurrent episodes of cellulitis. (7)
Frequent skin injuries — because of occupational, recreational, or other types of activities — also raise the risk for cellulitis. (2)
Being Obese or Overweight
Excess weight puts you at risk for cellulitis, because being overweight can make it harder for the body to fight infections. (8)
Being obese or overweight also increase the risk of developing lymphedema, another cellulitis risk factor, after cancer or cancer treatment, or from other causes. (9)
Fluid buildup in the arms and legs, called lymphedema, increases the risk for cellulitis. A common cause of lymphedema in the arms is the removal of lymph nodes between the breast and underarm during treatment for breast cancer.
Lymphedema in the legs can also occur as a result of cancer treatment, injury to the lymph nodes or lymph vessels in the legs, or certain infections.
Injection Drug Use
Previous research indicates that skin infections, including cellulitis, are common among injection drug users, particularly when users inject directly into skin or muscle tissue, rather than into a vein. (10) Use of unsterilized needles and inadequate skin cleansing before injection also raise the risk of infection, according to an article in the journal Archives of Clinical Microbiology. (11)
Of course, self-injecting drugs to get high has many other negative health and social effects besides skin infections. Getting treatment for a drug addiction is generally necessary to stop using drugs, stay off them, and pursue more productive life activities.
Cellulitis Prevention Tips
There are several steps you can take to prevent cellulitis from occurring in the first place or to prevent recurrent infections:
Protect Your Skin From Injury
Take precautions to avoid or prevent even minor skin injuries by doing the following:
- Apply sunscreen and insect repellent when spending time outdoors.
- Don’t pick at or scratch your skin.
- Keep your fingernails trimmed to help prevent scratching.
- Follow your doctor’s orders for treating eczema and other rashes or skin conditions.
- Learn to use knives and other sharp tools properly.
- Avoid burns when cooking by using hot pads to handle hot pots and pans and by wearing gloves when washing dishes.
- For construction or DIY projects or when using hazardous chemicals, wear protective gloves, boots, and safety goggles.
- When playing sports, wear appropriate protective gear.
- Don’t walk around barefoot, especially outdoors, and especially if you have diabetes.
- Don’t attempt “bathroom surgery” on calluses or corns.
Treat Wounds Promptly and Properly
If you do sustain a skin injury, clean it thoroughly with soap and water to rinse out any dirt, debris, or bacteria before an infection takes hold. Cover cuts, scrapes, burns, and broken blisters with gauze or an adhesive bandage.
Keep injuries covered until they heal, changing the bandage daily.
Monitor wounds and look for any signs of infection. If your symptoms get worse rather than better, progress quickly, or become severe, go to the emergency department, warns Tsippora Shainhouse, MD, a board-certified dermatologist at SkinSafe Dermatology and Skin Care in Beverly Hills, California, and a clinical instructor at the University of Southern California.
“Regular reassessment of the skin by a healthcare provider is critical for appropriate management,” Dr. Shainhouse notes.
Wash Your Hands Regularly
Regularly washing your hands can also stop the spread of some bacterial infections. You should wash hands for at least 20 seconds, which is the length of singing the “Happy Birthday” song twice. (12)
Dry your hands with a clean cloth, and apply moisturizer to your hands and skin on a regular basis. This can prevent skin dryness and cracking.
Make Healthy Lifestyle Changes
Since being obese or overweight can increase the risk for cellulitis, take steps toward losing some weight by limiting your intake of sugar and fast food, eating plenty of unprocessed fruits and vegetables, and increasing your daily physical activity.
You should also stop smoking if you smoke, and limit your intake of alcohol to no more than one drink per day for women and no more than two drinks per day for men. Both smoking and heavy drinking can increase the risk of cellulitis.