Cellulitis
Cellulitis is a common skin infection caused by bacteria. It affects the middle layer of the skin (dermis) and the tissues below. Sometimes, muscle below the skin can be affected.
Skin layers
The skin is the largest organ of the body. The skin and its derivatives (hair, nails, sweat and oil glands) make up the integumentary system. One of the main functions of the skin is protection. It protects the body from external factors such as bacteria, chemicals, and temperature. The skin contains secretions that can kill bacteria and the pigment melanin provides a chemical pigment defense against ultraviolet light that can damage skin cells. Another important function of the skin is body temperature regulation. When the skin is exposed to a cold temperature, the blood vessels in the dermis constrict. This allows the blood which is warm, to bypass the skin. The skin then becomes the temperature of the cold it is exposed to. Body heat is conserved since the blood vessels are not diverting heat to the skin anymore. Among its many functions the skin is an incredible organ always protecting the body from external agents.
Causes
Staphylococcus and streptococcus bacteria are the most common causes of cellulitis.
Normal skin has many types of bacteria living on it. When there is a break in the skin, these bacteria can cause a skin infection.
Risk factors for cellulitis include:
- Cracks or peeling skin between the toes
- History of peripheral vascular disease
Peripheral vascular disease
Peripheral artery disease (PAD) is a condition of the blood vessels that supply the legs and feet. It occurs due to narrowing of the arteries in the...
Read Article Now Book Mark Article - Injury or trauma with a break in the skin (skin wounds)
- Insect bites and stings, animal bites, or human bites
Insect bites and stings
Insect bites and stings can cause an immediate skin reaction. The bite from fire ants and the sting from bees, wasps, and hornets are most often pai...
Read Article Now Book Mark Article - Ulcers from certain diseases, including diabetes and vascular disease
Ulcers
An ulcer is a crater-like sore on the skin or mucous membrane. Ulcers form when the top layers of skin or tissue have been removed. They can occur ...
Read Article Now Book Mark Article - Use of corticosteroid medicines or other medicines that suppress the immune system
- Wound from a recent surgery
Symptoms
Symptoms of cellulitis include:
- Fever with chills and sweating
Fever
Fever is the temporary increase in the body's temperature in response to a disease or illness. A child has a fever when the temperature is at or abov...
Read Article Now Book Mark ArticleChills
Chills refers to feeling cold after being in a cold environment. The word can also refer to an episode of shivering along with paleness and feeling ...
Read Article Now Book Mark ArticleSweating
Sweating is the release of liquid from the body's sweat glands. This liquid contains salt. This process is also called perspiration. Sweating helps...
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Fatigue
Fatigue is a feeling of weariness, tiredness, or lack of energy.
Read Article Now Book Mark Article - Pain or tenderness in the affected area
- Skin redness or inflammation that gets bigger as the infection spreads
Skin redness or inflammation
Rashes involve changes in the color, feeling or texture of your skin.
Read Article Now Book Mark Article - Skin sore or rash that starts suddenly, and grows quickly in the first 24 hours
Rash
Rashes involve changes in the color, feeling or texture of your skin.
Read Article Now Book Mark Article - Tight, glossy, stretched appearance of the skin
- Warm skin in the area of redness
- Muscle aches and joint stiffness from swelling of the tissue over the joint
Muscle aches
Muscle aches and pains are common and can involve more than one muscle. Muscle pain also can involve ligaments, tendons, and fascia. Fascias are th...
Read Article Now Book Mark Article - Nausea and vomiting
Nausea and vomiting
Nausea is feeling an urge to vomit. It is often called "being sick to your stomach. "Vomiting or throwing-up forces the contents of the stomach up t...
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Exams and Tests
Your health care provider will perform a physical exam. This may reveal:
- Redness, warmth, tenderness, and swelling of the skin
- Possible drainage, if there is a buildup of pus (abscess) with the skin infection
- Swollen glands (lymph nodes) near the affected area
Swollen glands
Lymph nodes are present throughout your body. They are an important part of your immune system. Lymph nodes help your body recognize and fight germ...
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Your provider may mark the edges of the redness with a pen, to see if the redness goes past the marked border over the next several days.
Tests that may be ordered include:
- Blood culture
Blood culture
A blood culture is a laboratory test to check for bacteria or other germs in a blood sample.
Read Article Now Book Mark Article - Complete blood count (CBC)
Complete blood count (CBC)
A complete blood count (CBC) test measures the following:The number of white blood cells (WBC count)The number of red blood cells (RBC count)The numb...
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- A biopsy may be done if other conditions are suspected
Biopsy
A skin lesion biopsy is when a small amount of skin is removed so it can be examined under a microscope. The skin is tested to look for skin conditi...
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Treatment
You will likely be prescribed antibiotics to be taken by mouth. You may be given pain medicine as well, if needed.
At home, raise the infected area higher than your heart to reduce swelling and speed up healing. Rest until your symptoms improve.
You may need to stay in a hospital if:
- You are very sick (for example, you have a very high temperature, low blood pressure, or nausea and vomiting that does not go away)
- You have been on antibiotics and the infection is getting worse (spreading beyond the original pen marking)
- Your immune system is not working well (due to cancer, HIV, or other medical condition)
- You have an infection around your eyes
- You require antibiotics through a vein (IV)
Outlook (Prognosis)
Cellulitis usually goes away after taking antibiotics for 7 to 10 days. Longer treatment may be needed if cellulitis is more severe. This may occur if you have a chronic disease or your immune system is not working properly.
People with fungal infections of the feet may have cellulitis that keeps coming back, especially if you have diabetes. Cracks in the skin from the fungal infection allow the bacteria to get into the skin.
Diabetes
Diabetes is a long-term (chronic) disease in which the body cannot regulate the amount of sugar in the blood.
Read Article Now Book Mark ArticlePossible Complications
The following may result if cellulitis isn't treated or treatment doesn't work:
- Blood infection (sepsis)
Sepsis
Sepsis is an illness in which the body has a severe, inflammatory response to bacteria or other germs.
Read Article Now Book Mark Article - Bone infection (osteomyelitis)
Osteomyelitis
Osteomyelitis is a bone infection. It is caused by bacteria or other germs.
Read Article Now Book Mark Article - Inflammation of the lymph vessels (lymphangitis)
- Inflammation of the heart (endocarditis)
Endocarditis
Endocarditis is inflammation of the inside lining of the heart chambers and heart valves (endocardium). It is caused by a bacterial or, rarely, a fu...
Read Article Now Book Mark Article - Infection of the membranes covering the brain and spinal cord (meningitis)
Meningitis
Meningitis is an infection of the membranes covering the brain and spinal cord. This covering is called the meninges.
Read Article Now Book Mark Article - Shock
Shock
Shock is a life-threatening condition that occurs when the body is not getting enough blood flow. Lack of blood flow means the cells and organs do n...
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When to Contact a Medical Professional
Call your provider right away if:
- You have symptoms of cellulitis
- You are being treated for cellulitis and you develop new symptoms, such as persistent fever, drowsiness, lethargy, blistering over the cellulitis, or red streaks that spread
Lethargy
Fatigue is a feeling of weariness, tiredness, or lack of energy.
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Prevention
Protect your skin by:
- Keeping your skin moist with lotions or ointments to prevent cracking
- Wearing shoes that fit well and provide enough room for your feet
- Learning how to trim your nails to avoid harming the skin around them
- Wearing appropriate protective equipment when participating in work or sports
Whenever you have a break in the skin:
- Clean the break carefully with soap and water. Apply petroleum jelly every day.
- Cover with a bandage and change it every day.
- Watch for redness, pain, drainage, or other signs of infection.
Reviewed By
Ramin Fathi, MD, FAAD, Director, Phoenix Surgical Dermatology Group, Phoenix, AZ. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.
Dinulos JGH. Bacterial infections. In: Dinulos JGH, ed. Habif's Clinical Dermatology. 7th ed. Philadelphia, PA: Elsevier; 2021:chap 9.
Gabel C, Ko L, Kroshinsky D. Cellulitis and erysipelas. In: Lebwohl MG, Heymann WR, Coulson IH, Murrell DF, eds. Treatment of Skin Disease: Comprehensive Therapeutic Strategies. 6th ed. Philadelphia, PA: Elsevier; 2022:chap 39.
Pasternack MS, Swartz MN. Cellulitis, necrotizing fasciitis, and subcutaneous tissue infections. In: Bennett JE, Dolin R, Blaser MJ, eds. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases. 9th ed. Philadelphia, PA: Elsevier; 2020:chap 93.