Browse categories and answer follow-up questions to refine your symptom profile.
Approach to the Critical Patient
Triage and escalation
Escalation triggers
If fever with hypotension, activate sepsis pathway
MAP < 65 mmHg after initial fluids
Lactate >= 2 mmol/l
If rapidly progressive pain out of proportion, necrotizing soft tissue infection pathway
Crepitus
Skin anesthesia
If diffuse erythema with skin tenderness and systemic toxicity, staphylococcal scalded skin syndrome pathway
Periorificial crusting
Positive Nikolsky sign
If orbital symptoms with periocular involvement, orbital cellulitis pathway
Pain with extraocular movements
Proptosis
Immediate stabilization
If shock, initiate fluid resuscitation and vasopressor per protocol
Balanced crystalloids
Norepinephrine first-line for persistent hypotension
If airway threat from facial soft tissue swelling, early airway planning
Anesthesia support
ENT support
Key concepts
Impetigo essentials
Superficial epidermal bacterial infection
Nonbullous form most common
Bullous form due to toxin-producing Staphylococcus aureus
Primary impetigo on intact skin
Minor trauma
Insect bites
Secondary impetigo over dermatoses
Eczema
Scabies
Coding and standardization
ICD-10
L01.00 impetigo unspecified
L01.01 nonbullous impetigo
L01.03 bullous impetigo
SNOMED CT concepts
Impetigo disorder
Bullous impetigo disorder
Infection control
Transmission reduction
Contact precautions for weeping lesions in clinical setting
Gloves and gown for direct contact
Hand hygiene before and after contact
School and daycare exclusion guidance planning
Exclusion until 24 hours after starting effective antibiotics
Cover lesions when feasible
History
Presenting features
Symptom pattern
Honey-colored crusted erosions
Often around nares and mouth
Mild pruritus common
Vesicles or pustules preceding crusts
Lesions at different stages
Minimal pain typical
Bullae with thin roof and collarette of scale
Rupture leaving shallow erosions
Regional outbreaks in children
Time course
Onset and progression
New lesions over days
Failure of simple hygiene measures
Prior similar episodes
Recurrent impetigo
Household clustering
Exposures and risks
Epidemiologic risks
Close contact environments
Daycare or school
Contact sports
Household contacts with skin infection
Shared towels or bedding
Shared razors
Host risks
Atopic dermatitis
Excoriations
Barrier dysfunction
Scabies exposure
Nocturnal pruritus in household
New rash in contacts
Diabetes mellitus
Poor wound healing
Higher complication risk
Immunocompromise
Systemic steroids
HIV
Community MRSA risk factors
Prior MRSA infection or colonization
Recent incarceration or shelter living
Red flags and complications history
Systemic symptoms
Fever
Concern for invasive infection
Alternative diagnosis consideration
Malaise
Staphylococcal toxin syndromes
Bacteremia concern in high-risk hosts
Complication clues
Dark urine or edema after skin infection
Post-streptococcal glomerulonephritis concern
Recent sore throat not required
Severe pain, rapidly spreading erythema, skin discoloration
Necrotizing infection concern
Urgent escalation
Periorbital swelling or vision symptoms
Periorbital or orbital cellulitis concern
Urgent escalation
Physical Exam
Skin findings
Lesion morphology
Nonbullous pattern
Erythematous papules evolving to vesicles or pustules
Honey-colored crusts on erosions
Bullous pattern
Flaccid bullae with clear or yellow fluid
Collarette of scale after rupture
Ecthyma features
Punched-out ulcer with adherent crust
Induration extending into dermis
Distribution
Face
Perinasal and perioral predominance
Angular cheilitis involvement
Extremities
Exposed areas
Sites of trauma or insect bites
Severity and systemic assessment
Vital signs
Fever
Consider deeper infection or alternative diagnosis
Threshold-based escalation per local sepsis protocol
Tachycardia
Pain vs infection severity
Dehydration consideration in children
Regional findings
Lymphadenopathy
Tender regional nodes
Lymphangitic streaking
Cellulitis extension
Diffuse warmth and edema beyond crusts
Rapid progression concern
PITFALLS
Misclassification risks
HSV labialis mistaken for impetigo
Grouped vesicles
Burning or pain prodrome
Allergic contact dermatitis mistaken for impetigo
Linear or geometric pattern
Clear exposure trigger
Scabies with secondary impetiginization
Burrows
Interdigital involvement
Differential Diagnosis
Infectious mimics
Bacterial and toxin syndromes
Ecthyma
Deeper ulcerative lesions
Higher scarring risk
Periorificial dermatitis with secondary infection
Papulopustular eruption
Irritant triggers
Staphylococcal scalded skin syndrome
Diffuse erythema and tenderness
Superficial desquamation
Viral and fungal
Herpes simplex
Grouped vesicles on erythematous base
Painful lesions
Varicella or zoster
Dermatomal distribution for zoster
Lesions in multiple stages for varicella
Tinea faciei
Annular plaques with scale
Central clearing
Inflammatory and other
Dermatitis and infestations
Atopic dermatitis flare
Lichenification
Flexural predominance
Allergic contact dermatitis
Pruritic erythematous plaques
Vesiculation in exposure pattern
Scabies
Burrows
Nocturnal pruritus
Autoimmune blistering
Bullous pemphigoid
Tense bullae
Older adult predominance
Pemphigus vulgaris
Painful erosions
Mucosal involvement
Laboratory Tests
When labs are needed
Lab indications
Systemic toxicity
CBC for leukocytosis trend
Lactate for sepsis risk stratification
Suspected renal complication
Creatinine and electrolytes
Urinalysis for hematuria and proteinuria
Immunocompromised host with extensive disease
CBC for neutropenia
Blood cultures if febrile
Microbiology
Pathogen identification strategy
Lesion culture and susceptibility
Recurrent impetigo
Treatment failure after 48 to 72 hours
Community outbreak investigation
MRSA colonization consideration
Prior MRSA history
High local prevalence settings
Diagnostic Tests
Scoring Systems
Clinical decision tools
No validated impetigo severity score in routine ED use
Severity based on lesion count and distribution
Systemic symptoms as escalation criterion
Treatment selection framework
Limited localized lesions
Topical antibiotic preferred
Add hygiene and lesion coverage
Multiple lesions or outbreaks
Oral antibiotic consideration
Culture if recurrent or failure
MRI
MRI role
Not routine for uncomplicated impetigo
Superficial epidermal process
Clinical diagnosis typical
Deep infection evaluation when concern exists
Osteomyelitis concern under chronic ulceration
Necrotizing infection differentiation support
CT
CT role
Not routine for uncomplicated impetigo
No expected deep tissue involvement
Avoid radiation in children when low value
Complication evaluation
Orbital cellulitis concern with periocular involvement
CT orbits with contrast per local pathway
Urgent specialty consultation
Ultrasound (or US)
Ultrasound role
Not routine for typical impetigo
No abscess expected in superficial crusted lesions
Clinical diagnosis sufficient
POCUS for abscess vs cellulitis when fluctuance or induration
Subcutaneous fluid collection
Incision and drainage pathway if present
Antibiotics adjunct decision based on severity
Cobblestoning without collection
Cellulitis management pathway
Oral antibiotic selection per local resistance
Disposition
Outpatient vs admission
Outpatient criteria
No systemic toxicity
Afebrile or low-grade fever without instability
Normal perfusion and mentation
Limited disease burden
Localized lesions
No rapidly progressive cellulitis
Reliable follow-up and hygiene capacity
Caregiver able to perform skin care in children
Ability to obtain medications
Admission or transfer criteria
Systemic illness
Sepsis physiology
Dehydration requiring IV fluids
Extensive skin involvement
Concern for toxin-mediated disease
Failure of outpatient therapy with progression
High-risk host
Significant immunocompromise
Inability to maintain wound care
Complications
Periorbital or orbital cellulitis concern
Necrotizing infection concern
Follow-up
Reassessment planning
Clinical improvement expectation
Less drainage and crusting by 48 to 72 hours
No new lesions after therapy initiation
Follow-up options
Primary care within 2 to 3 days if not improving
Dermatology for recurrent or atypical presentations
Treatment
General measures
Skin care and transmission control
Gentle cleansing
Warm water soaks to soften crusts
Mild soap cleansing once or twice daily
Lesion management
Keep nails short
Cover lesions with nonadherent dressing when feasible
Household measures
Avoid sharing towels, bedding, cosmetics
Launder clothing and linens in hot water when possible
Topical antibiotics
Localized impetigo regimen
Mupirocin 2% ointment
Apply thin layer three times daily for 5 days
Extend to 7 days if slow response
Avoid use if known mupirocin resistance locally high
Perinasal colonization use in recurrent disease
Intranasal application twice daily for 5 days
Combine with chlorhexidine washes for decolonization plan
Retapamulin 1% ointment
Apply twice daily for 5 days
Use for nonbullous impetigo
Not for mucosal surfaces
Age limits per local formulary
Avoid in very young infants if restricted
Confirm availability and coverage
Ozenoxacin 1% cream
Apply twice daily for 5 days
Option when available
Consider for localized lesions
Oral antibiotics
Indications for oral therapy
Numerous lesions
Widespread distribution
Multiple body sites
Bullous impetigo
Higher likelihood of S aureus
Outbreak control consideration
Topical failure
No improvement by 48 to 72 hours
New lesions despite adherence
MSSA and Streptococcus coverage options
Cephalexin
Adult dosing
500 mg PO four times daily for 5 to 7 days
Renal dosing adjustment when eGFR reduced
Pediatric dosing
25 to 50 mg/kg/day PO divided every 6 to 8 hours for 5 to 7 days
Maximum 4 g/day
Dicloxacillin
Adult dosing
500 mg PO four times daily for 5 to 7 days
Take on empty stomach if tolerated
Pediatric dosing
25 to 50 mg/kg/day PO divided every 6 hours for 5 to 7 days
Maximum per local pediatric limits
MRSA risk options
Clindamycin
Adult dosing
300 to 450 mg PO three times daily for 5 to 7 days
Monitor for antibiotic-associated diarrhea
Pediatric dosing
20 to 40 mg/kg/day PO divided every 6 to 8 hours for 5 to 7 days
Maximum per local pediatric limits
Trimethoprim-sulfamethoxazole
Adult dosing
1 to 2 double-strength tablets PO twice daily for 5 to 7 days
Limited streptococcal coverage consideration
Pediatric dosing
8 to 12 mg/kg/day trimethoprim component PO divided every 12 hours for 5 to 7 days
Avoid in infants under 2 months
Doxycycline
Adult dosing
100 mg PO twice daily for 5 to 7 days
Limited streptococcal coverage consideration
Pediatric constraints
Avoid under age 8 years unless specialist-directed
Photosensitivity counseling
Evidence and guideline framing
Class I recommendation for antibiotics in confirmed impetigo based on expert consensus
Topical preferred for limited lesions
Oral preferred for extensive disease
ACEP Level C alignment for uncomplicated skin infection antibiotic selection based on local resistance
Culture-driven adjustment for failure or outbreaks
MRSA coverage when epidemiologic risk high
Decolonization and recurrence
Recurrent impetigo strategy
Household cluster management
Treat symptomatic contacts
Emphasize hygiene and laundry measures
Decolonization regimen consideration
Intranasal mupirocin twice daily for 5 days
Repeat only with clinician direction
Resistance risk with frequent use
Chlorhexidine washes daily for 5 days
Avoid eyes and ears
Alternative dilute bleach baths per specialist plan
Special Populations
Pregnancy
Pregnancy considerations
Preferred agents
Topical mupirocin for localized disease
Cephalexin for extensive disease
Agents to avoid or use with caution
Doxycycline avoidance
Trimethoprim-sulfamethoxazole avoidance near term when possible
Lactation considerations
Avoid infant direct contact with treated area until absorbed
Avoid application on nipple area unless directed
Geriatric
Older adult considerations
Atypical presentations
Bullous lesions mistaken for autoimmune blistering disease
Higher risk of ecthyma with vascular disease
Medication safety
Renal dosing adjustment for cephalexin and trimethoprim-sulfamethoxazole
Drug interaction review for trimethoprim-sulfamethoxazole with warfarin
Skin integrity optimization
Emollients for xerosis reduction
Avoid adhesive trauma from dressings
Pediatrics
Pediatric essentials
First-line for limited lesions
Topical antibiotic for 5 days
Daycare and school exclusion planning
Oral therapy triggers
Numerous lesions
Bullous impetigo
Household outbreak dynamics
Weight-based dosing safety
Use mg/kg/day dosing with maximum limits
Caregiver education for adherence and hygiene
Background
Epidemiology
Population patterns
Common in children age 2 to 5 years
Daycare and school transmission
Summer and humid climate association
Risk increased with skin barrier disruption
Atopic dermatitis
Insect bites
Common organisms
Staphylococcus aureus
Group A Streptococcus
Pathophysiology
Mechanisms
Nonbullous impetigo
Superficial infection of epidermis
Vesiculopustules rupture to crusts
Bullous impetigo
Exfoliative toxin production by S aureus
Intraepidermal split leading to flaccid bullae
Complication pathways
Post-streptococcal glomerulonephritis after streptococcal strains
Bacteremia rare but possible in high-risk hosts
Therapeutic Considerations
Treatment rationale
Antibiotics shorten course and reduce transmission
Faster lesion resolution than hygiene alone
Reduced household spread
Topical vs oral decision
Topical for limited disease to reduce systemic adverse effects
Oral for extensive disease or bullous disease
Resistance considerations
MRSA prevalence variability by region
Mupirocin resistance risk with frequent decolonization
Patient Discharge Instructions
copy discharge instructions
Impetigo discharge instructions
Medication use
Use antibiotics exactly as prescribed
If topical, apply thin layer to lesions after gentle cleansing
Skin care
Wash hands before and after touching the area
Keep nails short and avoid scratching
Cover lesions with a clean nonstick dressing when possible
Prevent spread
Do not share towels, bedding, makeup, razors
Wash clothing, towels, and bedding regularly
Stay home from school or daycare until 24 hours after starting antibiotics
Expected improvement
Fewer new lesions within 1 to 2 days
Less crusting and drainage within 2 to 3 days
Return to ED now
Fever with worsening skin redness or swelling
Rapidly spreading redness or severe pain
Red streaks moving up the limb
Swelling around the eye, eye pain, vision changes
Vomiting, lethargy, signs of dehydration
No improvement after 48 to 72 hours of antibiotics
References
Clinical guidelines and evidence sources
Core references
Infectious Diseases Society of America skin and soft tissue infection guideline
Impetigo management recommendations
Culture and MRSA coverage considerations
American Academy of Pediatrics Red Book
Pediatric impetigo therapy and dosing guidance
School exclusion guidance
NICE antimicrobial prescribing guidance for impetigo
Topical vs oral selection framework
Antimicrobial stewardship emphasis
CDC community MRSA clinical resources
Risk factor framing
Hygiene and decolonization considerations
Evidence level conventions
ACEP Level A definition
High-quality evidence with consistent results
Rarely available for superficial SSTI treatment comparisons
ACEP Level B definition
Moderate evidence supporting common practice
Applies to selected SSTI antibiotic strategies by local resistance
ACEP Level C definition
Consensus and expert opinion
Applies to many impetigo operational decisions in ED settings
Class I definition
Benefit much greater than risk
Antibiotic therapy for confirmed impetigo in most patients
Class IIa definition
Benefit greater than risk
Culture in recurrent or outbreak settings
Class IIb definition
Benefit at least equal to risk
Decolonization regimens for recurrent disease in select households
SymptomDx is an educational tool for medical professionals. It does not replace clinical judgment. Verify all clinical data and drug dosages with authoritative sources.