What Is Cellulitis?

Cellulitis is a common bacterial skin infection. It typically presents as an inflamed area with associated pain and swelling. This article explores the causes, types, treatment options, and prevention tips related to cellulitis.

Cellulitis is a common but potentially severe bacterial infection that primarily affects the skin and skin tissues. Most people who experience cellulitis and treat the condition early with antibiotic therapy fully recover without much disruption to their life.

However, without treatment, cellulitis may lead to hospitalization. In addition, cellulitis is typically more challenging to resolve if you have a compromised immune system or a chronic medical condition.  

Several types of bacteria can cause cellulitis. However, the most common cause of cellulitis is group A strep bacteria. According to the Centers for Disease Control and Prevention (CDC), one 2017 study found that 45% of people who experienced cellulitis did so from group A strep bacteria.

Learn about bacterial diseases.

The symptoms of cellulitis will typically vary depending on the area of the body the infection affects.

Common symptoms of cellulitis include:

• inflamed skin, which may be more difficult to see on dark skin tones
• painful skin
• tenderness
• swelling
• skin in the affected area that is warm to the touch
• discoloration and inflammation that expands from the affected area

Other symptoms people may experience include:

• fever
• chills
• nausea
• blisters or ulcers
• red spots
• dimpling of the skin
• clear or yellow pus
• enlarged glands, such as your lymph nodes
• a general feeling of being unwell

Seek immediate medical care if you experience any of the following:

• The area affected is on your face.
• You have an animal or human bite.
• The discoloration is spreading quickly or is very painful.
• You have a chronic condition, such as diabetes, or a weakened immune system.

If you are experiencing any symptoms of cellulitis, it is important to contact a doctor. Without treatment, cellulitis can spread and become a more serious condition.

The appearance of cellulitis can differ depending on the area of the body it affects.

Cellulitis is a bacterial infection that affects the skin and skin tissues. Multiple strains of bacteria can be responsible for cellulitis, including:

• Staphylococcus pyrogens
• Staphylococcus aureus
• Streptococcus pneumoniae
• beta-hemolytic streptococci

Cellulitis is typically not transmissible from person to person. Bacteria entering the body through a break in the skin is what causes cellulitis. Such means of entry include:

• an injury
• an insect bite
• cracked skin
• peeling skin

Anyone can be susceptible to cellulitis. However, certain issues and conditions can increase your risk of developing cellulitis. These risk factors include:

• cuts, ulcers, and puncture wounds
• bites
• chronic skin conditions, such as eczema and athlete’s foot
• chickenpox and shingles
• chronic edema
• overweight or obesity
• chemotherapy
• HIV or AIDS
• long-term kidney disease or liver disease

Once you get cellulitis, you are not immune from getting it again. Keeping your skin moisturized and practicing good wound care are generally effective ways to help prevent cellulitis.

Proper wound care includes the following:

• Clean all minor cuts and scrapes immediately with soap and water.
• Clean and cover all open wounds with a sterile, dry bandage.
• Visit your doctor for all punctures and deep wounds.
• If you have an open wound, avoid pools, hot tubs, and natural bodies of water.
• Wash your hands often with soap and water.
• Keep your skin moisturized to prevent dry, cracked skin.
• If you use a personal protection pad or a diaper, change it often to keep your skin dry.
• If you have diabetes, protect your feet and check them daily.
• Check and treat athlete’s foot promptly, as it can lead to breaks in the skin.

Cellulitis is a common infection of the skin’s deep dermis and subcutaneous tissue. There are several conditions that may appear similar to cellulitis, including the following.

Erysipelas is often considered a form of cellulitis. However, it is a superficial infection affecting the upper dermis and superficial lymphatic system. This infection results from the exotoxins released from group A strep. Erysipelas manifests as a bright red color with well-defined boundaries, whereas cellulitis has undefined borders.

Chronic venous stasis dermatitis is a long-standing, bilateral, inflammatory infection that appears on the lower extremities. Its main features are flushed skin with scaling, peripheral edema, and hyperpigmentation. Treatment will focus on treating the underlying chronic venous insufficiency.

Necrotizing fasciitis is a rare skin infection that leads to the “death” of the subcutaneous tissue. Its classic presentation includes a fever, flushed skin, swelling, and pain. It is a medical emergency and requires immediate surgical intervention.

Septic arthritis, or an infected joint, can affect any joint but typically involves the knee joint. People typically present with joint swelling, pain, warmth, and decreased joint mobility. Joint aspiration and antibiotics are the typical treatments for this condition.

Deep vein thrombosis (DVT) generally presents on one side of the body only. It causes tenderness, skin flushing, warmth, and swelling. It often affects the lower extremities.

Learn if DVT is an emergency.

Doctors typically diagnose cellulitis by performing a physical exam. Generally, they are able to base their diagnosis on the appearance of the infection.

Diagnosis of cellulitis does not typically require laboratory tests or imaging.

In the case of cellulitis, the earlier your doctor initiates treatment, the more effective the treatment is. Your doctor will typically use medications or surgery to treat cellulitis. However, if the infection becomes very severe, you may require hospitalization for IV antibiotics.

Your doctor will typically prescribe oral antibiotics to target the bacteria that caused the infection. 

For non-purulent cellulitis, which means that the symptoms do not include pus, your doctor will most likely choose an antibiotic that will cover both S. aureus and group A strep.

Beta-lactam antibiotics are effective against group A strep bacteria. 

Your doctor can treat mild cellulitis with oral antibiotics that include:

• penicillin
• cephalosporins
• dicloxacillin
• clindamycin

In severe cellulitis where a systemic infection is present, IV antibiotics may be considered. These may include:

• penicillin
• ceftriaxone
• cefazolin
• clindamycin

The CDC recommends 5 days of antibiotic treatment for most cellulitis cases. In addition, treating predisposing factors — such as edema and underlying skin disorders — is recommended to reduce recurrent cellulitis infections.

If the infection spreads to deeper tissues, you may require surgery as well as antibiotics.

Some ways you can help manage your cellulitis and improve your healing at home include:

• applying a clean cloth to the affected area as often as you need
• elevating the affected area
• regularly moving the joint near the affected area to avoid stiffness
• drinking plenty of fluids to prevent dehydration
• not wearing compression socks until you have fully healed

Early treatment of cellulitis is critical to avoid more serious complications. These complications include potentially serious infections in areas such as the:

• blood
• joints
• bone
• lining of the chambers of your heart and heart valves

Cellulitis can also cause swelling in your veins if blood clots form close to the surface of the skin. Necrotizing fasciitis is the most severe, yet rare, complication that requires immediate medical attention.

Here are some more questions that people ask about cellulitis.

No. You cannot catch cellulitis from another person.

Cellulitis is generally the result of bacteria that get in through openings and cracks in the skin. This can often happen from the bacteria being under your fingernails. Proper handwashing and body hygiene can help prevent the bacteria that cause cellulitis from entering your body.

Cellulitis is a bacterial infection of the skin that can occur anywhere on the body in both children and adults. Typical symptoms include pain, flushed or discolored skin, swelling, and tenderness.

The best prevention is good wound and skin care. If you are at risk of cellulitis and have cuts, puncture wounds, or bites, keep a close eye on them for symptoms of infection. These symptoms may include fever, pus, and the skin being warm to the touch.

If you develop any symptoms of infection or cellulitis, contact your doctor right away, as untreated cellulitis can lead to serious complications.