Cellulitis; Causes, Symptoms and Treatment

Written by Timothy Okooboh

What is Cellulitis?

  • Cellulitis is a bacteria skin infection.
  •  It is an infection of the lower part of the dermis (inner layer of the skin) and subcutaneous tissues unlike impetigo that is an infection of the epidermis.
  • Cellulitis is characterized by the cardinal symptoms of inflammation which are, redness, hotness or warmth, pain and swelling of the affected skin area.
  • It affects various parts of the body. But cellulitis of the leg is more common.
Cellulitis of the leg

Cellulitis cannot be explained without mentioning a similar skin condition known as Erysipelas. While cellulitis affects the lower part of the dermis, erysipelas affects the upper part of the dermis (but not the epidermis). In other words, erysipelas is a superficial cellulitis. Their symptoms are similar that is, redness, pain, warmth and swelling. However, because erysipelas affects the upper part of the dermis, swelling of the affected skin area is higher compared to cellulitis. Therefore erysipelas is said to be associated with a markedly raised skin area or a defined raised skin border separate from the unaffected skin area.

Erysipelas characterized by a swollen inflamed butterfly appearing rash

Symptoms of Cellulitis

Cellulitis on the upper arm

Cellulitis is an inflammatory skin infection of the lower part of the dermis and subcutaneous tissues. The main symptoms are:

  • Redness (erythema)
  • Hotness or warmth
  • Pain
  • Swelling
  • Rash on the red skin area
  • In addition to the above symptoms, there can be pus, blisters or abscess depending on whether the cellulitis is purulent or non-purulent. Oh yes!, cellulitis occurs in either of two forms: purulent cellulitis (producing pus) or non-purulent cellulitis (no pus or blisters).

NB: Erysipelas is non-purulent

  • Systemic symptoms include fever, chills and malaise.

For more information about various skin lesions, see skin lesions.

Causes of Cellulitis

Cellulitis is a bacteria skin infection mainly caused by Beta-hemolytic streptococci (especially Streptococcus pyogenes) and Staphylococcus aureus. On rare occasions, it can be caused by other kinds of bacteria such as Pseudomonas and Clostridium.

NB: Purulent cellulitis is mainly caused by Staphylococcus aureus (especially MRSA). Non-purulent cellulitis and erysipelas (usually non-purulent in nature) are mainly caused by Streptococcus bacteria. 

Risk Factors for Cellulitis

Risk factors for developing cellulitis include:

  • History of cellulitis.
  • Skin trauma or a cut on the skin.
  • Tinea pedis, dermatitis, Impetigo.
  • Obesity
  • Venous insufficiency (poor blood supply to the tissues can decrease ability to fight infections).
  • Conditions associated with immune suppression such as Diabetes and HIV.

Complications of Cellulitis

Cellulitis can be life threatening as it is an infection of the deeper parts of the skin. Complications include:

  • Osteomyelitis (infection of the bone).
  • Sepsis or bacteremia (Infection of the blood)
  • Glomerulonephritis (inflammation of the glomerulus of the kidney).
Orbital Cellulitis; a severe form of cellulitis


Cellulitis is mainly diagnosed clinically by observation of the symptoms. However certain investigations can be carried out such as:

  • Blood culture if sepsis or bacteremia is suspected.
  • X-ray or MRI (magnetic resonance imaging) if osteomyelitis is suspected.

NB: Certain skin infections are similar to cellulitis. They include, erysipelas, lyme disease and necrotizing fascitis. Hence Cellulitis should not be diagnosed personally without conducting a medical professional.

Treatment of Cellulitis

Unlike impetigo, cellulitis is an infection of the deeper parts of the skin (the lower dermis and subcutaneous tissues). Therefore, it is not usually treated with topical antibiotics. Cellulitis is mainly treated with oral or injectable antibiotics.

NB: We live in an era of widespread antibiotic resistance. Therefore, we @Health Hub promote the use of appropriate antimicrobial sensitivity tests (as much as possible) before recommending antibiotics.

For severe cellulitis, the patient will usually be hospitalized and administered injectable antibiotics such as Vancomycin.

NB: Apart from the characteristic symptoms on the skin, severity is determined by body temperature >38°c, heart rate>90, respiratory rate>24, WBC>12000 cells/ul.

  • For non-severe cellulitis, choice of antibiotics may depend on whether or not it is purulent. If it is purulent, choice of antibiotics will be targeted at MRSA (methicillin resistant staph aureus). These antibiotics include clindamycin, doxycycline sulphamethoxazole-trimethoprim etc. Choice of antibiotics for non-purulent cellulitis will be targeted at Streptococcus pyogenes. These antibiotics include cephalexin, clindamycin, dicloxacillin, flucloxacillin etc., depending on antibiotic sensitivity test.

Home Remedies

Certain home remedies that can help to relieve the symptoms of cellulitis include:

  • Apply a heating pad or warm packs to the affected area for 15 minutes at least three times a day.

NB: If you have diabetes, don’t use a heating pad on your feet. This can increase the risk of diabetic foot problems. See some diabetic foot care tips.

  • Callendula contains antiinflammatory and antiseptic flavonoids that help with healing. Boil water containing callendula flowers, allow the mixture to cool and apply on the affected part.
Callendula flowers
  • Rest and raise the affected area, especially the legs and arms.


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Up next on skin health: Acne



2 thoughts on “Cellulitis; Causes, Symptoms and Treatment

  1. Pingback: Cellulitis – Health Hub

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