Viral exanthemMANAGEMENT

INFECTIOUS DISEASE PRESENTATIONS · 12 SECTIONS

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555 items

☷ Legend

01Approach to the Critical Patient/attcp62

First look and isolation

›Immediate priorities

›Airway patency

›Stridor

›Drooling

›Breathing status

›Increased work of breathing

›SpO2 trend

›Circulation status

›Capillary refill time

›Peripheral pulse quality

›Mental status

›AVPU

›New confusion

›Sepsis risk

›Hypotension for age

›Lactate elevation

›Isolation triggers

›Fever with cough coryza conjunctivitis

›Vesicular rash in clusters

›Immediate escalation triggers

›Shock physiology

›Tachycardia with delayed capillary refill

›Hypotension

›Purpura with fever

›Concern meningococcemia

›Broad spectrum antibiotics within 1 hour

›Mucosal involvement with skin pain

›Concern SJS TEN

›Burn center or ICU pathway

›Toxic appearance

›Altered mental status

›Rapidly progressive rash

Hemodynamic and monitoring targets

›Monitoring and targets

›Continuous pulse oximetry if respiratory symptoms

›SpO2 target at least 94 percent

›Lower target if chronic cyanotic disease per baseline

›Frequent vitals

›Trend heart rate

›Trend blood pressure

›Temperature trend

›Persistent fever beyond 5 days concern Kawasaki or MIS-C

›Hypothermia concern sepsis

›Hydration status

›Urine output trend

›Oral intake tolerance

Initial decision points

›Key decisions

›Likely benign viral exanthem

›Well appearing

›No red flags

›High consequence mimics

›Meningococcemia

›Kawasaki disease

›MIS-C

›SJS TEN

›Toxic shock syndrome

›Infection control

›Suspected measles airborne precautions

›Suspected varicella airborne and contact precautions

›Consultation triggers

›Dermatology for uncertain severe rash

›Infectious diseases for suspected measles or immunocompromise

›Pediatrics for infants or unstable vitals

02History/hx52

Core symptom pattern

›Presenting pattern

›Timeline of fever to rash

›Rash after fever resolution

›Rash with ongoing fever

›Rash evolution

›Started on trunk then spread

›Started on face then spread

›Pruritus

›Severe itch suggests urticaria or varicella

›Minimal itch common in roseola

›Pain

›Skin tenderness concern SJS TEN

›Limb pain concern meningococcemia or RMSF

Exposure and risk context

›Risks and exposures

›Sick contacts

›Daycare or school outbreak

›Household febrile illness

›Recent travel

›Measles exposure risk

›Arboviral risk zones

›Vaccination status

›MMR series

›Varicella vaccine

›Medication exposure

›New antibiotics within 1 to 3 weeks

›Anticonvulsants within 2 months

›Immune status

›Immunosuppressive therapy

›Primary immunodeficiency

›Pregnancy exposure context

›Parvovirus B19 exposure

›Rubella exposure

Syndrome specific clues

›Key associated symptoms

›URI symptoms

›Cough

›Coryza

›Conjunctivitis

›GI symptoms

›Vomiting

›Diarrhea

›Oral lesions

›Painful ulcers

›Koplik spots description

›Arthralgia

›Parvovirus B19

›Rubella

›Headache or neck stiffness

›Meningitis concern

›Encephalitis concern

›Sunlight sensitivity

›Photophobia

›Eye pain

03Physical Exam/exam55

Rash morphology and distribution

›Rash characterization

›Morphology

›Maculopapular

›Vesicular

›Petechial

›Purpuric

›Urticarial

›Distribution

›Face predominant

›Trunk predominant

›Acral predominant

›Blanching

›Blanching suggests benign viral or urticaria

›Nonblanching raises petechiae purpura differential

›Palpability

›Palpable purpura concern IgA vasculitis

›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

04Differential Diagnosis/ddx66

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

05Laboratory Tests/lt54

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

06Diagnostic Tests/dt41

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 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

07Disposition/dispo29

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

08Treatment/t74

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

09Special Populations/sp36

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

10Background/b36

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

11Patient Discharge Instructions/pdi27

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

12References/r23

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

Evidence & Review

Reviewed by SymptomDx Medical Team · Last reviewed June 16, 2026

SymptomDx is an educational tool for medical professionals. It does not replace clinical judgment. Verify all clinical data and drug dosages with authoritative sources.