Treatment algorithm

Please note that formulations/routes and doses may differ between drug names and brands, drug formularies, or locations. Treatment recommendations are specific to patient groups: see disclaimer

ACUTE

mild

1st line – oral antibiotic therapy

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ACUTE
|
mild
1st line – 

oral antibiotic therapy

Mild infection is characterized by typical cellulitis/erysipelas with no focus of purulence.

Most patients with mild cellulitis can be managed with outpatient therapy.[13] Hospitalization is only recommended if there is concern for a deeper or necrotizing infection, for patients with poor adherence to therapy, for infection in a severely immunocompromised patient, or if outpatient treatment is failing.[13]

Before starting treatment for cellulitis or erysipelas, UK guidelines from the National Institute for Health and Care Excellence (NICE) recommend considering drawing around the extent of the infection with a single-use surgical marker pen to monitor progress, but note that redness may be less apparent or appear more violaceous on darker skin tones.[23]

There is little high-quality evidence available to indicate the most appropriate antibiotic choice, route of administration, or duration.[66] Local antibiotic protocols should be consulted to determine the most appropriate choice of antibiotic based on local pathogen prevalence and antibiotic resistance patterns. The Infectious Diseases Society of America recommends penicillin V, a cephalosporin (e.g., cephalexin), dicloxacillin, or clindamycin.[13] The treatment of erysipelas should follow the same principles as that for cellulitis. In severe penicillin allergy in which there is type-I immediate hypersensitivity reaction, a non-beta-lactam antibiotic is indicated. Treatment can be narrowed to pathogen-targeted antibiotics in line with sensitivity results when they become available.

The recommended duration of antibiotic therapy depends on the severity and site of infection. IDSA recommends antibiotic therapy for 5 days in uncomplicated cellulitis. Treatment should be extended if it has not improved within this time period.[13] The World Society of Emergency Surgery (WSES) and the Surgical Infection Society Europe (SIS-E) recommend 7 to 14 days of antibiotic therapy for MRSA skin and soft-tissue infections. This should be individualized based on the patient’s clinical response.[61] The American College of Physicians recommends that patients with nonpurulent cellulitis should receive antibiotics for 5 to 6 days.[62]

Primary options

penicillin V potassium: 250-500 mg orally four times daily

OR

cephalexin: 250-500 mg orally four times daily

OR

dicloxacillin: 250 mg orally four times daily

OR

clindamycin: 300-450 mg orally four times daily

Consider – supportive management

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ACUTE
|
mild
Consider – 

supportive management

Treatment recommended for SOME patients in selected patient group

Supportive measures include the use of adequate pain relief, elevation of the affected area, and treatment of predisposing factors (such as edema or underlying cutaneous disorders).[13]

Adequate analgesia should be prescribed. Acetaminophen or a nonsteroidal anti-inflammatory drug (e.g., ibuprofen) are usually appropriate.

Primary options

acetaminophen: 325-1000 mg orally every 4-6 hours when required, maximum 4000 mg/day

OR

ibuprofen: 200-400 mg orally every 4-6 hours when required, maximum 2400 mg/day

moderate

1st line – intravenous antibiotic therapy

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ACUTE
|
moderate
1st line – 

intravenous antibiotic therapy

Sepsis should be suspected if there is acute deterioration in a patient in whom there is clinical evidence or strong suspicion of infection. Local sepsis protocols should be followed. See our topic "Sepsis in adults" for more information.

Moderate infection is characterized by typical cellulitis/erysipelas with systemic signs of infection. Systemic signs of infection include temperature >100.4°F (38°C), tachycardia (heart rate >90 beats per minute), tachypnea (respiratory rate >24 breaths per minute), or abnormal white blood cell count (>12,000 or <400 cells/microliter).[13]

Intravenous antibiotics are indicated. Intravenous antibiotics may be given in the outpatient setting if the facilities and expertise are available. Hospitalization is recommended if there is concern for a deeper or necrotizing infection, for patients with poor adherence to therapy, for infection in a severely immunocompromised patient, or if outpatient treatment is failing.[13]

Before starting treatment for cellulitis or erysipelas, UK guidelines from the National Institute for Health and Care Excellence (NICE) recommend considering drawing around the extent of the infection with a single-use surgical marker pen to monitor progress, but note that redness may be less apparent or appear more violaceous on darker skin tones.[23]

There is little high-quality evidence available to indicate the most appropriate antibiotic choice, route of administration, or duration.[66] Local antibiotic protocols should be consulted to determine the most appropriate choice of antibiotic based on local pathogen prevalence and antibiotic resistance patterns. The Infectious Diseases Society of America (IDSA) recommends penicillin G, ceftriaxone, cefazolin, or clindamycin.[13] The treatment of erysipelas should follow the same principles as that for cellulitis. In severe penicillin allergy in which there is type-I immediate hypersensitivity reaction, a non-beta-lactam antibiotic is indicated. Treatment can be narrowed to pathogen-targeted antibiotics in line with sensitivity results when they become available.

A switch from intravenous to oral antibiotics should occur once the patient is clinically stable (i.e., systemically well and comorbidities are stable).[61]

The recommended duration of antibiotic therapy depends on the severity and site of infection. IDSA recommends antibiotic therapy for 5 days in uncomplicated cellulitis, and advises that treatment should be extended if the infection is severe, or if it has not improved within this time period.[13] The World Society of Emergency Surgery (WSES) and the Surgical Infection Society Europe (SIS-E) recommend 7 to 14 days of antibiotic therapy for MRSA skin and soft-tissue infections. This should be individualized based on the patient’s clinical response.[61] The American College of Physicians recommends that patients with nonpurulent cellulitis should receive antibiotics for 5 to 6 days.[62]

Primary options

penicillin G potassium: 2-4 million units intravenously every 4-6 hours

OR

ceftriaxone: 1-2 g intravenously every 24 hours

OR

cefazolin: 1 g intravenously every 8 hours

OR

clindamycin: 600-900 mg intravenously every 8 hours

Consider – MRSA antibiotic cover

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ACUTE
|
moderate
Consider – 

MRSA antibiotic cover

Treatment recommended for SOME patients in selected patient group

Coverage for MRSA may be prudent in cellulitis associated with penetrating trauma (especially from illicit drug use), purulent drainage, or with concurrent evidence of MRSA infection elsewhere. Options for treatment of MRSA in those circumstances include intravenous vancomycin, linezolid, or daptomycin.[13]

Primary options

vancomycin: 15 mg/kg intravenously every 12 hours

OR

linezolid: 600 mg intravenously every 12 hours

OR

daptomycin: 4 mg/kg intravenously every 24 hours

Consider – supportive management

Back
ACUTE
|
moderate
Consider – 

supportive management

Treatment recommended for SOME patients in selected patient group

Supportive measures include the use of adequate pain relief, elevation of the affected area, and treatment of predisposing factors (such as edema or underlying cutaneous disorders).[13]

Thromboprophylaxis should be considered based on risk stratification, as for all patients admitted to hospital. Local protocols should be followed.

Adequate analgesia should be prescribed. Acetaminophen or a nonsteroidal anti-inflammatory drug (e.g., ibuprofen) are usually appropriate.

Primary options

acetaminophen: 325-1000 mg orally every 4-6 hours when required, maximum 4000 mg/day

OR

ibuprofen: 200-400 mg orally every 4-6 hours when required, maximum 2400 mg/day

severe

1st line – intravenous antibiotic therapy

Back
ACUTE
|
severe
1st line – 

intravenous antibiotic therapy

Sepsis should be suspected if there is acute deterioration in a patient in whom there is clinical evidence or strong suspicion of infection. Local sepsis protocols should be followed. See our topic "Sepsis in adults" for more information.

Patients with severe cellulitis include those who have failed oral antibiotic treatment or have systemic signs of infection, who are immunocompromised, or who have clinical signs of deeper infection such as bullae, skin sloughing, hypotension, or evidence of organ dysfunction. Systemic signs of infection include temperature >100.4°F (38°C), tachycardia (heart rate >90 beats per minute), tachypnea (respiratory rate >24 breaths per minute), or abnormal white blood cell count (>12,000 or <400 cells/microliter).[13]

There is little high-quality evidence available to indicate the most appropriate antibiotic choice, route of administration, or duration.[66] Local antibiotic protocols should be consulted to determine the most appropriate choice of antibiotic based on local pathogen prevalence and antibiotic resistance patterns. The Infectious Diseases Society of America (IDSA) recommends vancomycin plus piperacillin/tazobactam or imipenem/cilastatin.[13] The treatment of erysipelas should follow the same principles as that for cellulitis. In severe penicillin allergy in which there is type-I immediate hypersensitivity reaction, a non-beta-lactam antibiotic is indicated. Treatment can be narrowed to pathogen-targeted antibiotics in line with sensitivity results when they become available.

A switch from intravenous to oral antibiotics should occur once the patient is clinically stable (i.e., systemically well and comorbidities are stable).[61]

The recommended duration of antibiotic therapy depends on the severity and site of infection. IDSA recommends antibiotic therapy for 5 days in uncomplicated cellulitis, and advises that treatment should be extended if the infection is severe, or if it has not improved within this time period.[13] The World Society of Emergency Surgery (WSES) and the Surgical Infection Society Europe (SIS-E) recommend 7 to 14 days of antibiotic therapy for MRSA skin and soft-tissue infections. This should be individualized based on the patient’s clinical response.[61] The American College of Physicians recommends that patients with nonpurulent cellulitis should receive antibiotics for 5 to 6 days.[62]

Primary options

vancomycin: 15 mg/kg intravenously every 12 hours

-- AND --

piperacillin/tazobactam: 3.375 g intravenously every 6-8 hours

More

or

imipenem/cilastatin: 1 g intravenously every 6-8 hours

More

Plus – surgical inspection and debridement

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ACUTE
|
severe
Plus – 

surgical inspection and debridement

Treatment recommended for ALL patients in selected patient group

Emergent surgical inspection and debridement is indicated to rule out a necrotizing process.[13] See our topic "Necrotizing fasciitis" for more information.

Consider – supportive management

Back
ACUTE
|
severe
Consider – 

supportive management

Treatment recommended for SOME patients in selected patient group

Supportive measures include the use of adequate pain relief, elevation of the affected area, and treatment of predisposing factors (such as edema or underlying cutaneous disorders).[13]

Thromboprophylaxis should be considered based on risk stratification, as for all patients admitted to hospital. Local protocols should be followed.

Proactively aspirate and/or deroof any blisters using aseptic technique.[36] Aspirates should be sent for microbiological processing. Wound exudates should be managed if the skin ulcerates. Absorbent but nonadhesive dressings can be used according to local wound management protocols.[36]

Adequate analgesia should be prescribed. Acetaminophen or a nonsteroidal anti-inflammatory drug (e.g., ibuprofen) are usually appropriate.

Primary options

acetaminophen: 325-1000 mg orally every 4-6 hours when required, maximum 4000 mg/day

OR

ibuprofen: 200-400 mg orally every 4-6 hours when required, maximum 2400 mg/day

ONGOING

treatment failure

1st line – re-evaluation and antibiotic modification

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ONGOING
|
treatment failure
1st line – 

re-evaluation and antibiotic modification

Features that suggest treatment failure include persistence or worsening of clinical findings such as fever or pain, or extension of erythema in the involved area.

This should prompt consideration of infection with resistant strains of organisms, extension to deeper tissues (e.g., necrotizing fasciitis), abscess formation, or an alternative diagnosis, such as an inflammatory reaction to an immunization or insect bite, stasis dermatitis, gout, superficial thrombophlebitis, eczema, allergic dermatitis, or deep vein thrombosis.[52][59] It should be noted that cellulitis in the setting of chronic lymphedema or venous insufficiency is often slow to resolve.[26]

Considering the common etiologies of cellulitis, modifying antimicrobial therapy to provide activity for MRSA is a suggested initial step in management of a poorly responsive cellulitis.

frequent relapses

1st line – antibiotic prophylaxis

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ONGOING
|
frequent relapses
1st line – 

antibiotic prophylaxis

Prophylactic antibiotics such as oral penicillin V or erythromycin for 4 to 52 weeks should be considered in patients who have 3 to 4 episodes of cellulitis per year despite attempts to treat or control predisposing factors. This program should be continued so long as the predisposing factors persist.[13]

Local antibiotic protocols should be consulted to determine the most appropriate choice of antibiotic based on local pathogen prevalence and antibiotic resistance patterns.

Primary options

penicillin V potassium: 250 mg orally twice daily

OR

erythromycin base: 250 mg orally twice daily

Plus – treatment of underlying cause

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ONGOING
|
frequent relapses
Plus – 

treatment of underlying cause

Treatment recommended for ALL patients in selected patient group

Predisposing conditions such as edema, obesity, eczema, venous insufficiency, and toe web abnormalities should be identified and treated.[13]

Surgical intervention to correct lymphedema may be an option in some patients with recurrent disease.[63]

Chronic cellulitis is rare, usually occurs only in immunocompromised patients, and is restricted to indolent organisms. An alternative diagnosis to cellulitis is more likely.

Compression therapy may help reduce recurrence.[64]

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Please note that formulations/routes and doses may differ between drug names and brands, drug formularies, or locations. Treatment recommendations are specific to patient groups. See disclaimer

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