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Southern Cross Medical Library

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Cellulitis - symptoms, diagnosis, treatment

Cellulitis is a bacterial infection of the skin and underlying tissues. Symptoms include redness and swelling of the affected area, often accompanied by a feeling of being generally unwell. The skin of the face, neck, arms and legs is most often involved; however it can occur anywhere on the body. Treatment is with antibiotics. Cellulitis is not directly contagious.


Cellulitis is usually caused by streptococcal or staphylococcal bacteria that may be present on your skin, or external sources like in water, soil or animals that you come in contact with. Cellulitis is often, but not always, preceded by a skin problem such as a scrape, cut, puncture wound, insect bite, ulceration, or surgical wound; or another skin condition such as eczema, psoriasis or scabies.    Other factors than can increase the chances of developing cellulitis include:

  • Problems with circulation in the limbs
  • Diabetes 
  • Alcoholism
  • Obesity
  • Swelling of the legs
  • Pregnancy.
Orbital cellulitis affects the tissues around the eye. This form of cellulitis can be caused by bacteria that have spread from the nose, throat or sinuses.

Signs and symptoms

The onset of cellulitis is often sudden. A clearly defined area of skin becomes red and tender. It rapidly turns bright red, shiny, swollen and hot. During the initial stages of the rash there is often accompanying fever, chills, headache, nausea and a feeling of being generally unwell. The lymph nodes near the affected area may become swollen and tender.


Cellulitis can usually be diagnosed from its characteristic appearance. Blood tests and tissue cultures may be used to confirm the presence of bacterial infection.  In cases of orbital cellulitis, a CT scan (computerised tomography) may be recommended in order to precisely identify the extent of the infection.


It is important to seek prompt medical advice if cellulitis is suspected so that an accurate diagnosis can be made and effective treatment given. The condition is treated with antibiotics, usually penicillin-based. In most cases treatment with oral antibiotics is all that will be required to adequately treat the condition. Oral antibiotics are usually given for 5–10 days. In many cases improvement in symptoms occurs within 48 hours of starting treatment.
In cases where the cellulitis is severe, or where oral antibiotics do not prove effective, hospitalisation and treatment with intravenous antibiotics may be required.
If orbital cellulitis is suspected, assessment and treatment from an eye specialist (ophthalmologist) may be required as the potential side-effects of the condition include loss of vision and meningitis.
In all cases elevation of the affected area (where possible) and bed rest is important. Measures such as cold packs and pain relieving medication may be used to reduce pain and discomfort.
In rare cases the bacteria that caused the cellulitis can spread to the bloodstream and travel throughout the body. This is known as sepsis and it can be life-threatening. Aggressive hospital treatment with antibiotics will be required.
It is possible for cellulitis to recur. This is particularly true of patients who have an underlying medical condition such as diabetes, postphlebitic syndrome or HIV infection. In selected patients where recurrence is a serious problem, on-going preventative treatment with antibiotics may be recommended.


Leversha, Dr A and Anson, Dr K (2012) Cellulitis/Skin conditions. Starship Children’s Health Clinical Guideline. Starship Children’s Hospital. Auckland.
Stanway, Dr A. (2013) Cellulitis. New Zealand Dermatological Society Incorporated.
Rowland, B. M. (2001) Cellulitis. Gale Encyclopaedia of Medicine. Gale Group Health and Wellness Resource Centre. Farmington Hills. MI.
Last Reviewed – 16 April 2013 


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