Cellulitis
Infectious cellulitis, erysipelas included. Pregnancy and breastfeeding are outside the adult treatment recommendations.
Don't miss
- INESSS Institut national d'excellence en santé et services sociaux
| Decision | Guideline |
|---|---|
| Any alarm sign | Hospital consultation generally requiredSevere infection (unstable general state) is outside the tools' treatment recommendations. INESSS adult tool, p. 1, 2 and 4 opens in a new tabINESSS child tool, p. 1, 2 and 4 opens in a new tab |
| Necrotizing fasciitis | Exquisite, disproportionate or extreme pain, even at rest
Inflammation with subcutaneous swelling
Possible subcutaneous gas (crepitus) and hemorrhagic bullae
Necrosis or skin discoloration with foul fluid drainage
Fulminant progression INESSS adult tool, p. 2 opens in a new tabINESSS child tool, p. 2 opens in a new tab |
| Orbital involvement suspected | Marked pain
Limited or painful eye movements
Trouble or inability opening the eye
Chemosis
Proptosis
Vision change
Concurrent rhinosinusitis
Recent dental treatment (adult tool) INESSS adult tool, p. 2 opens in a new tabINESSS child tool, p. 2 opens in a new tab |
| Systemic involvement | Marked or persistent decline in general state
Severe cellulitis: hemodynamic instability, fever or hypothermia, tachycardia, tachypnea, hypotension INESSS adult tool, p. 2 opens in a new tabINESSS child tool, p. 2 opens in a new tab |
| Higher risk of complications | Rapid progression
Cervicofacial signs: dyspnea or dysphagia, sublingual edema, trouble opening the mouth or sticking out the tongue, extraoral fistulas, upper-jaw swelling reaching the lower lid
Preseptal (periorbital) cellulitis that is not a simple case
Cellulitis on an ischemic limb (adult tool)
Lymphangitic streak or necrosis
Risk of decompensating a major pre-existing comorbidity INESSS adult tool, p. 2 opens in a new tabINESSS child tool, p. 2 opens in a new tab |
| Site or deep involvement | Central face (danger triangle)
Perineum
Bone, tendon sheath or joint (osteomyelitis, tenosynovitis, arthritis) INESSS adult tool, p. 2 opens in a new tabINESSS child tool, p. 2 opens in a new tab |
Diagnose
- INESSS Institut national d'excellence en santé et services sociaux
| Decision | Guideline |
|---|---|
| Suspect | Usually one-sided on a limb, acute onsetContinuous redness with no healthy skin inside
A lymphangitic streak strongly suggests cellulitis INESSS adult tool, p. 2 opens in a new tabINESSS child tool, p. 2 opens in a new tab |
| Look-alikes | Some need no antibioticContact dermatitis, acute eczema, insect bite, herpes or zoster, panniculitis, stasis dermatitis, superficial phlebitis, joint involvement (septic arthritis, gout, synovitis), acute bursitis, hematoma, simple abscess or cyst, drug or vaccine reaction
Face: conjunctivitis, dacryocystitis
Erythema migrans, erythema nodosum, Sweet syndrome
Definitions in annex C of the tools INESSS adult tool, p. 3 and 11 opens in a new tabINESSS child tool, p. 3 opens in a new tab |
| MRSA | Rare causeSuspect it with pus plus one of:
Recurrent boils or abscesses
Recent MRSA infection or colonization in the person or family
Long or recent hospital stay
Recent invasive procedure
Risk behaviours such as injection drug use, or men who have sex with men (adult tool)
Crowded settings (military base, detention, homelessness, some community or sports settings)
Recent travel to a high-prevalence area INESSS adult tool, p. 3 opens in a new tabINESSS child tool, p. 3 opens in a new tab |
| Severity | Severity sets the route and the length of treatmentMild: stable general state, mild symptoms and signs
Moderate: stable, with more advanced signs, a wider area, rapid spread, or fever, tachycardia, leukocytosis or lymphadenopathy
Severe: unstable general state;
see Don't miss INESSS adult tool, p. 4 opens in a new tabINESSS child tool, p. 4 opens in a new tab |
| Simple preseptal (periorbital) | Only simple cases are treated in primary careSimple means:
Mild lid swelling and redness
No marked pain
Eye opens well
Eye movements normal and painless
Normal vision
No proptosis or chemosis
Good general state INESSS adult tool, p. 4 opens in a new tabINESSS child tool, p. 4 opens in a new tab |
Treat
- INESSS Institut national d'excellence en santé et services sociaux
- PIQ Protocole d'immunisation du Québec (MSSS)
| Decision | Guideline |
|---|---|
| Duration | 5 days is usually enough for mild cellulitis, or for moderate cellulitis whose inflammation improves even if swelling and redness have not fully cleared. INESSS adult tool, p. 4 and 5 opens in a new tabINESSS child tool, p. 4 and 5 opens in a new tab |
| Abscess | A drained abscess alone needs no antibioticAbscessed cellulitis over 5 cm across, abscess included: an oral antibiotic against S. aureus, or MRSA with its risk factors, may be added by judgment. INESSS adult tool, p. 4 opens in a new tabINESSS child tool, p. 4 opens in a new tab |
| MRSA cover | Only after microbiological confirmation, or with pus and an MRSA risk factorPreferred for mild and some uncomplicated moderate infections: Doxycycline, TMP-SMX, Clindamycin. doses: see INESSS adult tool, p. 13 opens in a new tab |
| Bite prophylaxis | May be recommended for a human or animal biteConditions:
Every cat bite
Deep tissue damage
Tendon, ligament, bone or joint involvement
Swelling at the wound
Moderate to severe wound, especially of the face, hand, foot or genitals
Immunity compromised by a condition or its treatment
Asplenia or advanced liver disease INESSS adult tool, p. 5 opens in a new tabINESSS child tool, p. 5 opens in a new tab |
| Post-exposure | Consider post-exposure prophylaxisTetanus vaccine for broken skin
Rabies vaccine for an animal bite
Hepatitis B immunoglobulin or vaccine, and HIV prophylaxis, when a human bite carries a transmission risk INESSS adult tool, p. 4 opens in a new tabINESSS child tool, p. 4 opens in a new tabPIQ opens in a new tab |
| Clindamycin | Resistance is possibleWarn about diarrhea and bowel symptoms that may worsen and need a visit. |
| Not printed here | See the adult tool |
| Drug | Dose | Duration |
|---|---|---|
| Oral | ||
| Cefadroxil | 500–1000 mg PO BID | 5 days (5–10) |
| Cephalexin | 500–1000 mg PO QID | 5 days (5–10) |
| Cloxacillin | 500 mg PO QID | 5 days (5–10) |
| IV: moderate, at risk of complications | ||
| Cefazolin | 2000 mg IV TID | 5 days with the oral step-down (5–10) |
| Ceftriaxone, if Cefazolin is contraindicated | 2000 mg IV DIE | 5 days with the oral step-down (5–10) |
| Penicillin allergy, after assessing the label | ||
| Cefuroxime | 500 mg PO BID | 5 days (5–10) |
| Drug | Dose | Duration |
|---|---|---|
| Animal (cat, dog) or human bite | ||
| Amox-clav 7:1, prophylaxis | 875/125 mg PO BID | 3–5 days |
| Amox-clav 7:1, treatment | 875/125 mg PO BID | 5–7 days |
| Dental origin | ||
| Amoxicillin | 500 mg PO TID | 3–7 days |
| Penicillin V | 300 mg PO QID | 3–7 days |
| Simple preseptal, sinus origin | ||
| Amoxicillin, with close follow-up | 1000 mg PO TID | 5–7 days (7–10) |
Follow-up
- INESSS Institut national d'excellence en santé et services sociaux
| Decision | Guideline |
|---|---|
| Return advice | Come back if, 48 h after the start:Systemic or allergic symptoms appear
General state, pain and fever are not better
The redness spreads past the drawn line INESSS adult tool, p. 7 opens in a new tabINESSS child tool, p. 7 opens in a new tab |
| Refer: failure or doubt | Refer by local pathwayNo better after 72 h of antibiotics
Recurrent cellulitis: think of a non-infectious cause such as venous insufficiency
Uncorrected dental problem, or more severe cellulitis of dental origin INESSS adult tool, p. 8 opens in a new tabINESSS child tool, p. 8 opens in a new tab |
| Refer: complex cases | Refer by local pathwayBite with a hepatitis B or HIV transmission risk
After surgery
Wound immersed in untreated water
Major or penetrating trauma
Infected diabetic foot (adult tool) INESSS diabetic foot GUO opens in a new tab
Immunomodulation or immunosuppression
Suspected prosthetic material infection
After a burn, by burn type and judgment
Complex abscess: extensive debridement; hands, face, ear, foot or genitals; several connected abscesses; suspected deep spread INESSS adult tool, p. 8 opens in a new tabINESSS child tool, p. 8 opens in a new tab |
| Beta-lactam allergy unclear | Experienced colleague, conseil numérique or allergy consultation when the reality or severity of the reaction is uncertain. INESSS adult tool, p. 8 opens in a new tabINESSS child tool, p. 8 opens in a new tab |
Children 3 months and older
- INESSS Institut national d'excellence en santé et services sociaux
| Decision | Guideline |
|---|---|
| Under 3 months | Outside the child toolNewborns risk a more invasive infection. Refer by local pathway. |
| Not printed here | See the child tool for bite, dental, preseptal, MRSA and penicillin allergy doses. |
| Drug | Dose | Duration |
|---|---|---|
| Oral | ||
| Cephalexin | 50–100 mg/kg/day PO divided TID (max 4500 mg/day) | 5 days (5–10) |
| Cloxacillin | 50–100 mg/kg/day PO divided QID (max 6000 mg/day) | 5 days (5–10) |
| IV: moderate, at risk of complications | ||
| Cefazolin | 50–100 mg/kg/day IV divided TID (max 6000 mg/day) | 5 days (5–10) |
| Ceftriaxone, if Cefazolin is contraindicated | 50–75 mg/kg/day IV DIE (max 2000 mg/day) | 5 days (5–10) |
Reviewed 17 October 2026 against the official sources below.
Sources
Blue square: Québec. The code names the body; each section's key gives its full name.