Nonpalpable petechiae concern thrombocytopenia or sepsis
Desquamation
Periungual peeling concern Kawasaki
Diffuse peeling concern toxic shock
Vital signs and general appearance
Severity assessment
Work of breathing
Retractions
Wheeze
Perfusion
Capillary refill
Skin mottling
Mental status
Irritability
Lethargy
Hydration markers
Dry mucosa
Decreased tears
Focused exam for red flags
High risk findings
Mucosal involvement
Oral erosions
Conjunctival injection with discharge
Eye findings
Photophobia
Corneal haze concern
Lymphadenopathy
Posterior auricular nodes suggest rubella
Generalized nodes suggest EBV
Hepatosplenomegaly
EBV
Hematologic malignancy mimic
Neck stiffness
Meningitis concern
Subarachnoid hemorrhage mimic in older teens
Extremity changes
Hand foot edema
Strawberry tongue
Joint exam
Symmetric small joint pain
Effusion
Differential Diagnosis
Likely viral exanthems
Common viral etiologies
Roseola infantum
High fever then rash
Trunk predominant maculopapular
Parvovirus B19 erythema infectiosum
Slapped cheek rash
Lacy body rash
Enterovirus exanthem
Summer and fall seasonality
Oral ulcers possible
Hand foot and mouth disease
Vesicles on hands feet mouth
Coxsackie A
Varicella
Lesions in different stages
Pruritic vesicles
Measles
Fever cough coryza conjunctivitis
Cephalocaudal spread
Rubella
Mild fever
Posterior auricular lymphadenopathy
EBV associated rash
With amoxicillin exposure
Pharyngitis and fatigue
High risk mimics and emergencies
Must not miss
Meningococcemia
Fever with petechiae or purpura
Rapid progression
Sepsis with DIC
Bleeding
Hypotension
Kawasaki disease ICD-10 M30.3
Fever at least 5 days
Mucocutaneous findings
MIS-C
Recent SARS-CoV-2 exposure
Shock or cardiac involvement
SJS TEN ICD-10 L51.1 L51.2
Skin pain
Mucosal erosions
Toxic shock syndrome
Hypotension
Diffuse erythroderma
Rocky Mountain spotted fever
Fever headache
Acral rash then central
Anaphylaxis with urticaria
Wheeze
Hypotension
Noninfectious causes
Other considerations
Drug eruption
Morbilliform rash
Temporal relation to medication
Urticaria
Transient wheals
Itch predominant
IgA vasculitis HSP ICD-10 D69.0
Palpable purpura
Abdominal pain
ITP ICD-10 D69.3
Petechiae
Isolated thrombocytopenia
Contact dermatitis
Localized exposure pattern
Vesicles or weeping plaques
Laboratory Tests
When labs are not needed
Low risk pathway
Well appearing
Normal vitals for age
Normal perfusion
Classic benign pattern
Roseola pattern
Parvovirus pattern
Supportive care only
No routine labs
Targeted labs for red flags
Evaluation for serious illness
Complete blood count for sepsis or hematologic concern
Neutrophilia supports bacterial infection
Lymphocytosis supports viral pattern
Platelet count for petechiae purpura
Thrombocytopenia suggests ITP or sepsis
Thrombocytosis supports Kawasaki subacute phase
CRP for inflammatory syndrome
Elevated supports Kawasaki or MIS-C
Normal does not exclude early disease
ESR for inflammatory syndrome
Elevated supports Kawasaki
Slower kinetics than CRP
Electrolytes for dehydration severity
Hyponatremia possible in severe infection
Bicarbonate as perfusion marker
Creatinine for renal involvement
MIS-C
IgA vasculitis
ALT AST for hepatitis or systemic illness
EBV
MIS-C
Coagulation studies for DIC concern
INR elevation
Fibrinogen low
Microbiology and serology
Etiology confirmation when clinically important
SARS-CoV-2 testing for MIS-C context
PCR for acute infection
Serology for prior infection
Measles testing for suspected measles
PCR from respiratory specimen
Measles IgM
Varicella testing in atypical cases
PCR from lesion
Serology if needed
Parvovirus B19 testing in pregnancy exposure
IgM and IgG
PCR if immunocompromised
Blood cultures for toxic appearance or sepsis concern
Before antibiotics when feasible
Do not delay antibiotics in shock
Lumbar puncture studies if meningitis concern
CSF cell count
CSF glucose mmol/l
CSF protein
Diagnostic Tests
Scoring Systems
Risk stratification tools
Pediatric Early Warning Score PEWS
Escalation threshold per local policy
Repeat scoring for trend
NICE traffic light system for fever in under 5 years
Green low risk
Amber intermediate risk
Red high risk
Sepsis screening pathway
Lactate threshold per local protocol
Hypotension trigger for resuscitation
MRI
MRI use cases
CNS symptoms with concern encephalitis
Altered mental status
Focal neurologic deficit
Musculoskeletal pain with concern osteomyelitis
Localized bone tenderness
Persistent fever
Contraindications
Unstable patient
Non MRI compatible implant
CT
CT use cases
Severe headache with neurologic signs
Concern intracranial infection complication
Concern hemorrhage mimic
Respiratory compromise with unclear source
CT chest only if strong indication after CXR
Avoid routine CT in uncomplicated viral illness
Contrast considerations
Renal impairment risk assessment
Allergy history
Ultrasound (or US)
US applications
Cardiac POCUS for shock with MIS-C concern
LV function estimate
Pericardial effusion
Lung US for pneumonia mimic
Focal consolidation
Pleural effusion
Abdominal US for IgA vasculitis complication
Intussusception concern
Free fluid
Disposition
Discharge criteria
Safe discharge
Well appearing
Normal mental status
Normal perfusion
No red flags
No petechiae purpura
No mucosal erosions
Hydration adequate
Tolerating oral fluids
Urination within expected interval
Reliable follow up
Return precautions understood
Primary care access
Admission and transfer criteria
Higher level care
Sepsis concern
Hypotension
Rising lactate
Petechiae purpura with fever
Observation or admission pending evaluation
Empiric antibiotics if concerning features
Suspected Kawasaki or MIS-C
Admission for monitoring and treatment
Echocardiography planning
Suspected SJS TEN
ICU or burn unit
Ophthalmology involvement
Immunocompromised with rash and fever
Lower threshold for admission
Antiviral therapy consideration
Treatment
Supportive care
Symptom control
Oral hydration
Small frequent fluids
Oral rehydration solution
Antipyretics
Acetaminophen PO 15 mg/kg every 4 to 6 hours
Maximum 60 mg/kg/day
Maximum 4000 mg/day for larger adolescents
Ibuprofen PO 10 mg/kg every 6 to 8 hours
Maximum 40 mg/kg/day
Avoid dehydration and renal impairment
Pruritus relief
Cetirizine PO 0.25 mg/kg daily
Typical adolescent 10 mg daily
Avoid duplication with other antihistamines
Diphenhydramine PO 1 mg/kg every 6 hours as needed
Maximum 50 mg per dose
Sedation risk
Topical emollients
Fragrance free moisturizer
Short lukewarm baths
Oral pain with enanthem
Viscous lidocaine avoidance in young children
Acetaminophen ibuprofen as above
Pathogen specific therapy
Antivirals when indicated
Varicella treatment indications
Immunocompromised
Severe disease
Older adolescents within 24 hours of rash onset
Acyclovir dosing
Acyclovir PO 20 mg/kg per dose four times daily
Maximum 800 mg per dose
Typical course 5 days
Acyclovir IV 10 mg/kg every 8 hours for severe disease
Renal dosing adjustment
Adequate IV hydration
Emergency therapies for dangerous mimics
Sepsis and meningococcemia pathway
If shock, fluid resuscitation 20 ml/kg isotonic crystalloid
Reassess after each bolus
Early vasopressors if fluid refractory
Empiric antibiotics for suspected meningococcemia
Ceftriaxone IV 50 mg/kg
Maximum 2 g
Alternative cefotaxime per local formulary
Airway and ventilation support
Escalate to critical care team
Early intubation if worsening mental status
Anaphylaxis pathway if urticaria with respiratory or cardiovascular compromise
Epinephrine IM 0.01 mg/kg of 1 mg/ml
Maximum 0.5 mg per dose
Repeat every 5 to 15 minutes as needed
Adjuncts
H1 antihistamine
Inhaled bronchodilator for wheeze
SJS TEN supportive pathway
Stop suspected culprit drug immediately
Antibiotics high risk
Anticonvulsants high risk
Pain control
Multimodal regimen
Avoid NSAIDs if renal risk
Transfer planning
ICU level monitoring
Burn unit consideration
Evidence and guideline notes
Evidence levels
Routine labs not indicated for well appearing classic viral exanthem
ACEP Level C consensus style approach
Pediatric practice standard
Measles suspected, airborne isolation and public health notification
CDC guidance
Infection control standard
Meningococcemia suspected, antibiotics without delay
Class I recommendation based on expert consensus for time critical sepsis care
Pediatric sepsis bundles
Special Populations
Pregnancy
Pregnancy considerations
Parvovirus B19 exposure
Maternal IgM IgG testing
Fetal hydrops risk counseling
Rubella exposure
Maternal serology
Obstetric consultation
Varicella exposure or disease
Varicella zoster immune globulin timing per guidance
Maternal pneumonia risk higher
Medication safety
Avoid teratogenic agents
Specialist input for antivirals
Geriatric
Older adult considerations
Immunosenescence
Atypical fever response
Higher complication risk
Medication adverse effects
Antihistamine anticholinergic burden
NSAID renal GI risk
Higher risk mimics
Drug eruption more likely with polypharmacy
Disseminated zoster risk
Pediatrics
Pediatric considerations
Age pattern
Roseola common in infants and toddlers
Hand foot and mouth common in young children
Dehydration risk
Oral ulcers limiting intake
Vomiting diarrhea
Weight based dosing
Verify kg weight
Maximum dose caps respected
Febrile infant pathway
Separate protocol for under 60 to 90 days
Lower threshold for labs and admission
Background
Epidemiology
Epidemiology
Viral exanthem frequency
Common cause of pediatric rash with fever
Many cases self limited
Seasonality
Enteroviruses summer and fall
Respiratory viruses winter
Public health relevance
Measles outbreaks in undervaccinated groups
Varicella breakthrough cases possible
Pathophysiology
Mechanisms
Immune mediated rash during viremia
Cytokine mediated inflammation
Dermal immune activation
Direct viral effect in epidermis
Vesicles in varicella
Vesicles in HFMD
Vascular injury patterns
Petechiae from thrombocytopenia
Purpura from vasculitis
Therapeutic Considerations
Treatment principles
Supportive care mainstay
Hydration
Fever control
Avoid unnecessary antibiotics
Viral etiology likely in classic presentations
Stewardship benefit
Targeted antivirals for selected infections
Varicella in high risk patients
HSV when clinically suspected severe disease
Early recognition of dangerous mimics
Petechiae with fever
Mucosal erosions with skin pain
Infection control
Measles airborne precautions
Varicella airborne and contact precautions
Patient Discharge Instructions
copy discharge instructions
Discharge instructions
Expected course
Rash may last several days
Fever should improve over 48 to 72 hours in most viral illnesses
Home care
Fluids and rest
Acetaminophen or ibuprofen dosing per weight
Contagion guidance
Hand hygiene
Avoid school until fever free per local policy
Return now
Trouble breathing
Blue lips
Severe sleepiness or confusion
Stiff neck
New seizure
Rash that does not blanch or looks like bruises
Rapidly spreading rash
Severe skin pain
Sores in mouth with poor drinking
Signs of dehydration
No urine for 8 hours
Very dry mouth
No tears
Follow up
Primary care in 24 to 72 hours if not improving
Earlier if fever persists beyond 5 days
References
Clinical guidelines and key sources
Core references
CDC clinical guidance for measles recognition isolation and reporting
Airborne precautions recommendations
Diagnostic testing recommendations
CDC clinical guidance for varicella management and infection control
Airborne and contact precautions recommendations
High risk antiviral indications
AAP Red Book guidance for viral exanthems and vaccine preventable diseases
Classic syndrome descriptions
Testing and public health actions
Pediatric sepsis bundle recommendations
Early antibiotics for suspected sepsis
Fluid resuscitation and vasopressor escalation
Dermatology consensus guidance for SJS TEN acute management
Culprit drug discontinuation
Burn unit level supportive care
Coding references
Coding and terminology
ICD-10 B09 unspecified viral infection characterized by skin and mucous membrane lesions
Use when viral exanthem unspecified
Consider R21 rash and other nonspecific skin eruption for symptom coding
SNOMED CT viral exanthem concept
Term alignment for problem list
Use organism specific concepts when known
SymptomDx is an educational tool for medical professionals. It does not replace clinical judgment. Verify all clinical data and drug dosages with authoritative sources.