What is Cellulitis? Causes, Definition, Symptoms and Treatment

Cellulitis is a disease in its own rights, but is mostly described as a skin condition. Two main strains of bacteria usually cause the disease, although a variety of bacteria strains can also cause it. The disease usually develops in the layers of the skin beneath the epidermis. These are known as the soft tissues, mostly consisting of the dermis and the subcutaneous layer. However, it can also occur on the upper skin layer. Without treatment, this bacterial infection can spread to the circulatory and lymphatic system. Cellulitis is considered dangerous in a such case.

The bacteria that cause cellulitis live harmlessly on the skin. When a fault such as an ulcer develops, the bacteria gain entry into the skin and this results in infection. The infection causes the affected areas to become red, warm, painful and swollen. In most cases, the lower legs are affected although any part of the skin can become infected.

Bacterial infections are usually not hard to treat, especially when caught early. However reassuring this may sound, this type of infections is potentially very dangerous when left without treatment or when misdiagnosed. Cellulitis, for example, can spread to vital organs in a matter of days. The good thing is that various forms of treatment are available, mostly the use of antibiotics.

What is cellulitis and its medical definition

So what is cellulitis? The simple cellulitis definition is that it is a bacterial infection that develops in the skin, and a potentially dangerous one. Medical definition usually includes the two bacteria that mostly cause the disease. These are staph and strep bacteria. Once the disease is past incubation stage, any “purulent” definition may include the fact that pus discharge is a potential sign.

It is very common to sustain a form of injury that will leave a part of the skin open. Common skin injuries include burns, cuts and ulcerations. Injuries can also come from being scratched by a pet or being bitten by an animal. If the injury has been sustained while working outdoors, such as on a farm, there are more chances of developing cellulitis.

First signs can appear around the injured area or somewhere different. It is however important to note that a number of other skin conditions can mimic cellulitis. For example, poor blood circulation in the lower legs causes swelling, pain and reddening.

The main difference is that cellulitis doesn’t cause scaling. It is also necessary that an opening be present somewhere on the skin for cellulitis to develop. The opening will act as an entry point for causal bacteria. Since the incubation period is usually not long, early signs will appear shortly after an injury.

Unlike most infections, cellulitis is rarely passed from one person to another. This is because causal bacteria are under the epidermis.

What does it mean to have cellulitis?

The difference between viruses and bacteria is that the latter can be permanently eradicated from the body after positive diagnosis. Once you have been diagnosed with cellulitis, it mostly indicates an urgent need to get antibiotics and keep more bacteria from entering the skin.

At times, cellulitis can arise as if from nowhere. This may be a sign that the patient is suffering from a chronic condition such as lymphedema or compromised immunity.

What causes cellulitis and how do you get it?

So far, cellulitis has been identified as a common infection caused by bacteria. But how do you get it? Bacteria are one of the most prolific living things. They live just about everywhere and in everything. Surprisingly, only a very small percent is actually harmful.

The skin among other things acts as a protective cover which keeps internal organs from harmful agents such as bacteria. Once the barrier is broken, cellulitis bacteria can freely invade the soft tissues of the skin and rapidly spread. Soft tissues are warm, rich with nutrients and moist, conditions that make it very convenient for bacteria to multiply quickly. While anyone can get cellulitis, there are several risk factors that may heighten the possibility of getting the infection. They include:

  • Skin injuries – broken skin regions are the leading causes of cellulitis. It is not always necessary that an injury be serious enough as to bleed or be an open wound. It can be something as seemingly not harmful as a cat scratch or an insect bite. You can for example get cellulitis from bee sting.
  • Some skin conditions – conditions such as athlete’s foot and eczema – cause tiny breaks in the skin. Such may allow bacteria to enter the skin. This is especially when the conditions are left without treatment. The disadvantage is that patients may mistake cellulitis signs with effects of the primary condition.
  • Weak immunity – the body naturally recognizes harmful bacteria and fights them off. In people with conditions or taking medications which may compromise the immune system, it will be hard for this natural defense mechanism to be effective. Immune-compromising conditions include HIV, diabetes and cancer. Some medications such as corticosteroids and drugs used in chemotherapy may also compromise the immune system.
  • Vascular defects – blood vessels and lymphatic vessels are responsible for efficient circulation of fluids in the body. When there are defects in these systems, the extremities are usually affected. Such defects result in swelling in lower legs which may also cause pain and reddening. Being obese is a major contributing factor. Sometimes, a chronic condition known as lymphedema develops. It is caused by poor drainage of lymphatic fluid in lower legs. Excess swelling in affected legs may lead to cracking and hence entry points for bacteria. Lymphedema cellulitis is a bit harder to treat.
  • Drug abuse – use of drugs that require injections is an efficient method of introducing bacteria into the skin. This is especially when needles are shared.
  • Previous cellulitis infection – previous infections, mostly ones occurring on lower legs heighten the chances of a recurring infection.
  • UV radiation – light skinned people are prone to sunburns and other forms of skin damage caused by UV radiation. Bacteria can take advantage of the resulting damage as entry points into the skin.

Other risk factors include surgeries, presence of foreign materials or objects in the skin and chronic wounds or bone infections. Note that risk factors do not necessarily cause a disease. Having a risk factor does not guarantee that a disease will certainly occur. It only increases the chances of the disease occurring.

Cellulitis symptoms and early signs

Early cellulitis symptoms begin shortly after infection. Some bacteria strains produce early signs within 24 hours. The symptoms usually appear around the infected region but may also occur somewhere else on the skin. Apart of the skin may:

  • Become red and inflamed
  • Be painful and feel tender
  • Develop a rapidly spreading cellulitis rash
  • Feel warm
  • Become firm and appear swollen

Sometimes, other signs of infection will be present. Such include presence of red streaks, formation of pus which may ooze, inflammation of local lymph nodes and fever. These signs indicate a spreading cellulitis which is potentially dangerous. Medical attention is necessary in the advent of such signs. A doctor should also be consulted if the area feels numb, hardened or when signs such as vomiting and high fever set in.

What does it look like?

If you were to look at pictures of a skin condition known as stasis dermatitis, you will notice their resemblance with those of cellulitis. In fact, symptoms of cellulitis in leg can easily be taken for those of dermatitis.

The main difference is that cellulitis tends to spread fast, is painful, and doesn’t itch. Affected areas also don’t become scaly like in the case of dermatitis. Dermatitis is the same condition known as eczema. It is common in people with dry skins. First signs include itchiness, mild pain, slight inflammation and formation of red scaly patches on the skin. When it occurs in the lower legs, the ankles and shin are mostly affected. Dermatitis also not contagious and doesn’t spread.

There are many cellulitis infection pictures online that may help identify the condition. If doubts are to persist, you can always consult your doctor for a medical diagnosis.

How is cellulitis diagnosed?

Diagnosis is usually very important to rule out other conditions with almost identical first signs. Most doctors will recognize cellulitis after a physical examination. Available nursing diagnosis for cellulitis tests include:

Physical examination

The doctor will look for signs and symptoms such as a swollen red area. The patient will be required to provide details on the timeline of the symptoms and a brief medical history. It may therefore be helpful to come up with a list of the symptoms you have been experiencing when preparing for an appointment.

Blood test

It is through blood that most substances, including immune system cells, are transported. By checking the number of white blood cells in the blood, a doctor will be able to predict the presence of bacteria. More white blood cells mean that there are harmful microbes in the blood.

Culture test

Tissue cells and bacteria can be put in conditions that allow them to proceed normal growth outside the body. This is done under controlled conditions in the lab. In case of cellulitis, fluid is drawn from the affected area and cultured.

Imaging tests

A chronic wound or infection can be caused by an object that has accidentally been trapped under the skin. It is through imaging tests that such an object can be traced and marked for removal. X-rays are usually used.

Medical cellulitis treatment

Medical cellulitis treatment is almost wholly done with antibiotics. Your doctor may however include treatment measures meant to reduce pain or manage the primary cause of cellulitis such as diabetes. In rare cases, a form of surgical operation will be performed even for cellulitis eye treatment.

Use of antibiotics

Antibiotics are very powerful drugs when used against bacteria. In most cases, cellulitis will completely be gone in 10 day duration of taking antibiotics. This, however, depends on the severity of the infection. Some patients are required to take antibiotics for 3 weeks while others only have to take them for about 10 days. Most symptoms will be gone or will have improved in the first 3 days. If this happens, patients should continue taking the prescribed drugs as instructed. Symptoms that don’t respond to antibiotics in the first 3 days should be reported to a doctor. Penicillin and Cephalexin for cellulitis are examples of antibiotics that can be used.

Pain management

Doctors usually prescribe pain relievers as part of cellulitis treatment. Even when this is not the case, patients can always purchase pain medications over the counter. It is very important that pain medications not be taken as the only form of treatment for cellulitis.

Managing pre-existing conditions

Sometimes, cellulitis occurs as a complication of conditions such as obesity, diabetes and use of medications. This means that the primary cause must be addressed if the resulting cellulitis is to be effectively treated. The doctor will still treat the cellulitis however. Often, treatment will be done in the hospital under a doctor’s supervision.


Not often is surgery used for cellulitis removal. When used, it is mainly to get rid of the collected fluid or pus that may be causing symptoms such as warmth and pain. Surgery can also be done to remove surrounding tissue that has died due to infection.

When to see a doctor

Severe cellulitis can lead to death, however mild early signs may be. While a patient may get good results from over the counter medications or even some home remedies, medical attention is always the better choice. See your doctor if:

  • Symptoms don’t improve in the first 3 days of taking antibiotics
  • You are experiencing high fevers or increased blood pressure
  • Infection starts or spreads to the neck and head areas. Cellulitis lip infection can, for example, rapidly spread to the brain.
  • The cellulitis is possibly resulting from a pre-existing condition
  • Unexplained swelling starts in lower legs and doesn’t go away
  • You have sustained a deep injury, a severe bite or blistering in an existing wound
  • An open skin area comes into contact with dirt or sea water
  • An elderly person or a child has been infected
  • You have tonsillar cellulitis

Possible complications

In most cases, early signs of a disease are not ones posing the greatest risk. Cellulitis can for example lead to the following if not treated:


An abscess is a swollen body area that contains pus and usually very painful. It resembles a large boil. Abscesses are caused by bacterial accumulation.


This is an acronym for a bacterium that doesn’t respond to some antibiotics. Scientists are warning of potential global medical crisis, where most bacteria will become resistance to antibiotics. If this happens, common diseases such as TB will return to the top killing menaces they used to be. One way to stop this rising resistance is to avoid unnecessary use of antibiotics, and getting medical help for common infections such as cellulitis.

Blood poisoning

All living organisms produce waste products. When bacteria are inside the body, their waste products are emptied into the blood system of the host. This may lead to a condition known as septicemia, which usually drives patients to shock.

Flesh-eating disease

Its medical name is necrotizing fasciitis. It is a bacterial infection complication that causes death to soft tissues.

Like most infections, cellulitis can lead to death if not treated.

Cellulitis treatment at home and prevention

Cellulitis is one of the most common infections. It may be helpful to learn how to treat it at home or basically how to avoid the infection.

Home treatment

  • Elevation – fluids, especially blood, flow away from the heart with more pressure than when going back to the heart. When cellulitis occurs in lower legs for example, you can improve its symptoms by keeping the affected leg elevated above the heart. This allows for more blood flow away from the leg.
  • Hygiene – practicing good hygiene is both preventive and curative. By keeping an injured skin area clean, you will be ensuring that no bacteria enter the skin. The few that may enter will possibly be fought off by the immune cells. It is also helpful to bandage the injured area.
  • Use warm compress – warm compress is perhaps the most widely used home treatment for many skin conditions. It works by encouraging dilation in blood vessels, which in turn allows for more efficient blood flow. This reduces inflammation. Warm compressing is also known to draw pus towards the surface where it can drain. To use a warm compress, soak a thick wash cloth in warm water, squeeze it to get rid of running water and press it on the affected part for 5-15 minutes. Repeat this twice a day.
  • Try natural products – tea tree oil is a good example of natural products hailed for their abilities to reduce inflammation and fight off bacterial infections. Essential oils, on the other hand, excel in soothing irritated skin. When using tea tree oil for cellulitis, it is important that it be diluted with carrier oil such as coconut oil to avoid skin irritation. Take caution when using natural products before consulting a doctor. This is especially for periorbital cellulitis treatment.


Once you have sustained a form of injury that leaves the skin broken, there are a number of precautions you should consider taking:

  • Avoid direct contact – there are more bacteria on our skins than we can count. In fact, staph bacteria, the strain mostly responsible for cellulitis lives on human skin. Exposing an injured skin area to these bacteria is almost guaranteed to end up in an infection.
  • Avoid exposure – bacteria can only cause cellulitis once inside the skin. By keeping an injured area protected, you will largely keep the harmful microbes from entering. This is especially when preventing or dealing with cellulitis on finger, hands or feet.
  • Always remember to clean – the simple form of bacteria allows them to multiply in numbers in a very short duration. This makes it necessary to keep cleaning an injured skin area, preferably with an anti-bacterial soap or agent.
  • Keep from contaminated surfaces – overcrowded places are usually very contaminated. Not only can you pick different types of microbes from surfaces but also from direct skin to skin contact. When such places and surfaces cannot be avoided, other measures such as covering the injured area will help.

Other practices that may help include:

  • Keeping the affected organ active to keep it from getting stiff
  • Managing the pain with over the counter pain medications
  • Avoiding tight clothing
  • Keeping the skin well moisturized to avoid conditions such as eczema and psoriasis
  • Wearing gloves especially when working outdoors or indoors with harsh chemicals
  • Wearing socks and well-fitting footwear