Cellulitis: Everything You Need to Know

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Cellulitis is a common infection of the skin, almost always caused by bacteria. The infection can come on suddenly and usually spreads from the skin surface (epidermis) and then goes deeper into the dermis and the subcutaneous fat layers.1

Cellulitis can cause redness, skin swelling, pain, heat at the site, and possibly fever. It is not contagious and typically affects only one site in the body at a time (for example, just one leg). Antibiotics are used to treat cellulitis but it's common for an infection to relapse (recur).2

cellulitis

Illustration by Alexandra Gordon for Verywell Health

Symptoms

Cellulitis symptoms include redness, swelling, and pain in the skin. It can also cause the skin to blister and peel. While cellulitis can occur anywhere on the body, it is most common on: 

  • Feet3
  • Lower legs (about 70% to 80% of cases)4
  • Arms (cellulitis is often associated with breast cancer treatment)5

Sometimes, red streaks extend from the original site of the infection. Additional symptoms also include:6

  • Warm or hot skin
  • Bruising
  • Blisters
  • Fever
  • Headache
  • Chills
  • Weakness

Cellulitis is a serious bacterial infection of the skin. If left untreated, cellulitis can spread and cause complications. If you have symptoms of cellulitis, see your healthcare provider. 

Pictures of What Cellulitis Looks Like

The following pictures of cellulitis on legs and feet offer a sense of how affected skin may look in both early stages and further on.

This photo contains content that some people may find graphic or disturbing.

cellulitis on a leg

DR P. MARAZZI / SCIENCE PHOTO LIBRARY / Getty Images

Cellulitis on a leg

Wendy Townrow / Getty Images

This photo contains content that some people may find graphic or disturbing.

A leg with cellulitis

Reproduced with permission from © DermNet New Zealand www.dermnetnz.org 2023.

Cellulitis on a foot

Wendy Townrow / Getty Images

This photo contains content that some people may find graphic or disturbing.

Cellulitis on an ankle

LagunaticPhoto / Getty Images

Causes

Cellulitis occurs when bacteria enter a break in the skin, most often in the legs and feet. This could be a nick, cut, or tear caused by an injury, surgery, bug bite, or needle.7 It could also be a breakdown of the skin's integrity due to a skin condition like eczema or athlete’s foot, often with itching.

It can affect those who have swelling in their legs due to venous stasis, or lymphedema after surgery for breast cancer.5 People with vein grafts used during surgery, or who have varicose veins and treatments for them, may not clear bacterial infection as quickly and tend to have more cases of cellulitis.8

Cellulitis is more common in older adults but can happen in any age group and either gender.7 A 2017 study also found that when cellulitis occurs, it is more likely to be severe in older people.4

Who's at Risk for Cellulitis?

Certain conditions can increase the risk of cellulitis. Diabetes, for example, makes both infection and cellulitis complications more likely.9 Other factors and conditions that increase risk include:10

  • Age
  • Obesity
  • Varicose veins (or certain surgical treatments for them)
  • Chickenpox or shingles7
  • Chronic leg edema (swelling), as with heart failure
  • Alcohol misuse and liver cirrhosis11
  • Immune system compromise
  • Breast cancer treatment (leading to lymphedema)

Types of Cellulitis

Cellulitis infections are often caused by the bacteria Staphylococcus aureus (including methicillin-resistant Staphylococcus aureus known as MRSA) and Group A Streptococcus.2 Many cases of Staph aureus are now resistant to the antibiotics that once worked.

There are a few rare causes of less common types of cellulitis. Some of these can be dangerous in those at risk—such as those who are immunosuppressed, have diabetes, lack a spleen, or have liver problems. They can include:

  • Cat and other animal bites, which can be deep and more dangerous than commonly realized. They can introduce Pasteurella multocida, leading to serious infections of the skin and deeper structures.12
  • Dog bites can in rare cases lead to a serious Capnocytophaga infection, including symptoms of facial cellulitis.13
  • Exposure to marine environments, such as fishing or walking by the sea, can lead to Vibrio parahaemolyticus. This is a bacterial infection that can be fatal if not quickly treated.14 There are about a dozen vibrio types, including V. vulnificus infections caused by eating seafood.15
  • Freshwater exposure can be associated with Aeromonas hydrophila infections.16 Children sometimes have infections with Haemophilus influenza.17

Surgery can lead to cellulitis, even rare types like mycobacterial infections. Those who are immunocompromised can be prone to a wide range of infections, like Pseudomonas, Proteus, Fusarium, and Serratia. Those at risk may require different antibiotics upfront, even though most cellulitis cases are caused by either Staph or Strep infections.18

Diagnosis

Cellulitis is usually diagnosed based on its appearance, but certain tests may be used to confirm a diagnosis, inform decisions about treatment, or evaluate how treatments have worked. This includes:6

  • Blood testing: Sometimes healthcare providers will check a person’s blood count to see if the white blood cells are elevated due to the immune system is fighting infection. In people who are very ill, blood cultures may be used to see if the bacteria has spread into the bloodstream.19
  • Aspiration: Injecting sterile fluid into the infected tissue and then drawing fluid out may be used to identify any captured bacteria.20 This is usually done only in extreme cases since aspirations may return inconclusive results.
  • Skin biopsy culture: A small sample of the affected skin is removed and placed in a petri dish to see if bacteria grow.21 This may be performed if the diagnosis is uncertain and/or to rule out conditions that can mimic cellulitis, like a drug reaction or vasculitis.

An ultrasound or magnetic resonance imaging (MRI), may be used to distinguish cellulitis from another diagnosis, like a deep venous thrombosis (DVT) or osteomyelitis, a bone infection.

Conditions that can be mistaken for cellulitis include:22

  • Irritant dermatitis
  • Lipodermatosclerosis
  • Lymphedema
  • Venous eczema

Treatment

Treatment for cellulitis usually consists of oral antibiotics. Most people get better quickly and do not require hospitalization.18

Antibiotics may be selected by the healthcare provider to cover the most likely types of bacteria, depending on what specific risks the patient has or the likelihood of antibiotic resistance.23

A healthcare provider may mark the borders of the infection to monitor its growth. They also may elevate a body part to help with drainage while expecting the infection to recede in a day or two. However, if someone becomes more ill or febrile (feverish), or the infection is not diminishing, they may need to be hospitalized and may need IV antibiotics.

Cellulitis often occurs due to another underlying condition. Treatment for cellulitis also includes treatment of the underlying condition.7

Complications

Several complications may arise as a result of cellulitis. They include:

  • Abscess: An abscess can form from severe infections. An abscess is a pocket of infection that can be difficult to clear. It may need drainage and not just antibiotics.18
  • Orbital cellulitis: This occurs when bacteria spread to the areas around the eye, often in children. It is a serious infection which can lead to loss of sight and even the spread of bacteria to the meninges or brain.24
  • Necrotizing fasciitis: This rare infection of deep skin layers can cause extreme pain and spread very quickly. It can quickly lead to the death of the tissues in these layers (subcutaneous and fascia) and prove fatal without rapid treatment. Surgery may be needed.25
  • Sepsis: Sepsis can occur when the bacteria from the skin reach deeper and spread through the blood, seeding other parts of the body. This can be very serious, requiring hospitalization and IV antibiotics.

Prevention

The best prevention of cellulitis is to take care of any break in the skin, which includes:

  • Washing the wound daily with soap and water
  • Applying a topical antibiotic to the wound
  • Keeping the wound covered with a bandage
  • Changing the bandage daily (or more often if it gets dirty or wet)

Avoiding insect bites by using repellent, or wearing flip-flops to avoid athlete's foot at the pool, may help to prevent infection. Keep in mind that certain lifestyle choices and behaviors, including intravenous drug use and body piercings or tattoos, can increase the risk of cellulitis.7

Talk with your healthcare provider about any underlying health condition that increases your risk for developing cellulitis, such as poorly controlled diabetes. Foot checks are important in those with diabetic neuropathy to make sure you don’t have any skin breakdown, ulcers, or wounds.

When to Seek Urgent Care

Cellulitis can be an urgent medical concern. Seek immediate medical attention for cellulitis if the red area of the skin expands quickly or you experience fever or chills.3 Other symptoms of severe cellulitis, or related complications such as sepsis, can include:26

  • Dehydration
  • Low blood pressure
  • Confusion
  • Shortness of breath

You should contact your healthcare provider if cellulitis treatments haven't worked. If skin tissue appears like it's dying (necrosis) or organs aren't functioning well (like the kidneys), seek care.

Keep in mind that older people may be more at risk for infection. Underlying health conditions also can contribute to the need for urgent care.7

Summary

Cellulitis is a skin infection that comes on quickly and can turn serious. While some bacteria live on the skin at all times and are generally harmless, if they enter the skin, they can cause infection.

If you notice any swelling, redness, pain, or heat at a site where you’ve had a cut, bite, or burn on your body, contact your healthcare provider. Seek medical care immediately if you experience shortness of breath, low blood pressure, or other more severe symptoms.

A Word From Verywell

Cellulitis is a common and potentially dangerous skin infection. A break in the protective skin barrier, no matter how small, can be the portal through which bacteria can enter. All cuts, abrasions, and bug bites should be cleaned and dressed with a band-aid and antibiotic ointment. If swelling, redness, warmth to the touch, or pain occurs, seek medical evaluation. When recognized early, treatment can be successful with oral antibiotics.

26 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Megan Coffee, MD
Megan Coffee, MD, PhD, is a clinician specializing in infectious disease research and an attending clinical assistant professor of medicine.