Infectious mononucleosisMANAGEMENT

INFECTIOUS DISEASE PRESENTATIONS · 12 SECTIONS

⚲

388 items

☷ Legend

01Approach to the Critical Patient/attcp38

Immediate priorities

›Stabilization triggers

›Airway compromise

›Stridor

›Muffled voice

›Drooling

›Inability to handle secretions

›Hemodynamic instability

›SBP < 90 mmHg or age adjusted hypotension

›Persistent tachycardia with poor perfusion

›Severe dehydration

›Poor oral intake with orthostasis

›Oliguria

›Concern for splenic rupture

›LUQ pain or left shoulder pain

›Syncope or presyncope

›Peritonitis

›Immediate actions

›If airway compromise, escalate to resuscitation bay and early airway planning

›Anesthesia and ENT consultation

›Avoid paralytic only intubation if severe upper airway edema

›If shock, initiate IV access and isotonic crystalloid bolus

›Reassess after each bolus for perfusion and respiratory status

›Massive transfusion protocol if hemorrhagic shock suspected

›If suspected splenic rupture, activate surgical consult and expedite imaging

›Type and screen

›Crossmatch if unstable or high suspicion

Key concepts

›Clinical framing

›Epstein-Barr virus primary infection causing infectious mononucleosis

›Triad

›Fever

›Pharyngitis

›Lymphadenopathy

›Major early hazards

›Upper airway obstruction from tonsillar hypertrophy

›Splenic rupture

›Hematologic complications

›Hemolytic anemia

›Severe thrombocytopenia

02History/hx48

Symptom pattern and timeline

›Illness course

›Duration of fever

›> 5 to 7 days

›Persistent fatigue weeks

›Sore throat characteristics

›Severe odynophagia

›Voice change

›Fatigue and functional decline

›Missed school or work

›Reduced exercise tolerance

›Exposure context

›Saliva exposure

›Kissing

›Shared drinks or utensils

›Close contact outbreaks

›Dormitory

›Team sports

Risk factors and red flags

›Complication risk

›Contact sports participation

›Recent play since symptom onset

›Planned return timeline

›Immunocompromise

›Transplant

›Chemotherapy

›Advanced HIV

›Red flag symptoms

›Dyspnea

›Stridor

›Orthopnea

›Abdominal pain

›LUQ pain

›Referred left shoulder pain

›Bleeding symptoms

›Petechiae

›Epistaxis

›Neurologic symptoms

›Severe headache

›Neck stiffness

›Focal deficits

Medication and allergy history

›Prior antibiotics for current illness

›Aminopenicillin exposure

›Amoxicillin

›Ampicillin

›Rash after antibiotic exposure

›Diffuse maculopapular eruption

›Analgesic and antipyretic use

›Acetaminophen total daily dose estimate

›NSAID use and contraindications

03Physical Exam/exam41

General and vitals

›Severity markers

›Toxic appearance

›Hydration status

›Dry mucous membranes

›Orthostatic vitals

›Respiratory effort

›Accessory muscle use

›Stridor

›Vital sign pattern

›Fever

›Tachycardia

›Hypotension

Head and neck

›Oropharynx

›Tonsillar hypertrophy

›Kissing tonsils

›Uvular deviation concern for peritonsillar abscess

›Exudative pharyngitis

›Palatal petechiae

›Lymph nodes

›Posterior cervical lymphadenopathy

›Generalized lymphadenopathy

›Airway warning findings

›Muffled hot potato voice

›Trismus

›Drooling

Chest and abdomen

›Hepatosplenomegaly

›Splenic tenderness

›Hepatic tenderness

›Abdominal peritoneal signs

›Rebound or guarding

›LUQ pain with referred left shoulder pain

Skin and hematologic signs

›Rash

›Maculopapular eruption

›Urticaria or angioedema concern for true drug allergy

›Bleeding stigmata

›Petechiae

›Ecchymoses

PITFALLS

›Diagnostic pitfalls

›Early disease with negative heterophile test

›Exudative pharyngitis mimicking streptococcal pharyngitis

›Peritonsillar abscess and epiglottitis masquerading as severe sore throat

04Differential Diagnosis/ddx29

Life threatening and must not miss

›Airway threats

›Epiglottitis

›ICD-10 J05.1

›Peritonsillar abscess

›ICD-10 J36

›Retropharyngeal abscess

›ICD-10 J39.0

›Hemorrhagic abdomen

›Splenic rupture

›ICD-10 S36.0

›Ectopic pregnancy in pregnancy capable patients

›ICD-10 O00

Infectious mimics

›Viral pharyngitis syndromes

›Cytomegalovirus mononucleosis

›Acute HIV seroconversion

›Adenovirus

›Bacterial causes

›Group A streptococcal pharyngitis

›ICD-10 J02.0

›Diphtheria in unvaccinated or travel exposure

›ICD-10 A36

›Other systemic infections

›Toxoplasmosis

›Viral hepatitis

Noninfectious

›Hematologic and oncologic

›Lymphoma

›Leukemia

›Inflammatory

›Kawasaki disease in pediatrics

05Laboratory Tests/lt29

Core labs for complications

›Hematology and inflammation

›Complete blood count for cytopenias and atypical lymphocytes

›Lymphocytosis with atypical lymphocytes supports diagnosis

›Severe thrombocytopenia prompts bleeding risk pathway

›Peripheral smear if severe cytopenias or diagnostic uncertainty

›Atypical lymphocytes

›Hemolysis features if anemia present

›Hepatic evaluation

›ALT and AST for hepatitis pattern

›Mild to moderate transaminase elevation common

›Marked elevation prompts alternate hepatitis evaluation

›Total bilirubin for cholestasis or hemolysis

›Direct predominance suggests cholestasis

›Indirect predominance suggests hemolysis

Point of care and situational labs

›Hydration and renal status

›Electrolytes including sodium and potassium for dehydration

›Repletion guided by clinical status

›Avoid hypotonic fluids for significant dehydration

›Pregnancy and bleeding context

›Urine or serum pregnancy test in pregnancy capable patients

›Guides imaging choices for abdominal pain

›Ensures safe medication selection

›Hemorrhage suspicion

›Type and screen for suspected splenic injury or significant bleeding

›Crossmatch if unstable

›Serial hemoglobin if ongoing concern

PITFALLS

›Lab interpretation pitfalls

›Normal CBC does not exclude early infectious mononucleosis

›Transaminase elevation is nonspecific and may reflect alternate hepatitis etiologies

06Diagnostic Tests/dt35

Scoring Systems

›Clinical criteria and decision support

›Infectious mononucleosis clinical suspicion features

›Posterior cervical lymphadenopathy

›Fatigue with prolonged course

›Palatal petechiae

›Streptococcal pharyngitis decision tools are not diagnostic for EBV

›Centor or McIsaac can guide strep testing decisions

›Co infection possible

›No validated scoring system reliably predicts splenic rupture risk

›Activity restriction based on time course and clinical recovery

›Imaging does not reliably clear early return to contact sports

MRI

›MRI role

›Not routine for uncomplicated infectious mononucleosis

›Limited availability and low yield in typical presentations

›Reserve for focal neurologic complication evaluation

›CNS complication contexts

›Encephalitis

›Myelitis

›CT indications

›Suspected splenic rupture or intraabdominal hemorrhage

›Contrast CT abdomen and pelvis if stable

›Surgical consultation should not be delayed if unstable

›Deep neck infection concern

›CT neck with contrast for peritonsillar or retropharyngeal abscess concern

›Consider airway risk before transport

Ultrasound

›Ultrasound applications

›Focused assessment for free fluid if hemodynamic instability with abdominal pain

›Positive free fluid increases urgency for surgical evaluation

›Negative study does not exclude splenic injury

›Spleen assessment limitations

›Splenomegaly measurement does not reliably predict rupture risk

›Do not use spleen size alone to authorize contact sport return

›Ultrasound pregnancy pathway

›Pelvic ultrasound if abdominal pain with positive pregnancy test

›Ectopic pregnancy exclusion

07Disposition/dispo25

Admission and higher level of care

›Admission indications

›Airway compromise or impending obstruction

›Stridor

›Inability to tolerate oral intake

›Severe dehydration

›Failed oral challenge after antiemetic and analgesia

›Significant electrolyte abnormalities

›Significant hematologic complications

›Severe thrombocytopenia with bleeding

›Hemolytic anemia with symptoms or instability

›Suspected splenic rupture

›Hemodynamic instability

›Peritoneal signs

›Significant hepatitis with concern for liver failure

›Encephalopathy

›Coagulopathy concern

Discharge criteria and follow up

›Discharge suitability

›No airway risk

›Adequate oral intake and pain control

›Reliable return precautions and follow up

›Follow up plan

›Primary care follow up within 3 to 7 days if persistent symptoms

›Return to sports clearance pathway

›Symptom resolution

›Shared decision making for timing

08Treatment/t57

Supportive care

›Hydration and nutrition

›Oral hydration strategies

›Frequent small volumes

›Electrolyte solutions if vomiting or diarrhea

›IV fluids for dehydration

›0.9% sodium chloride 10 to 20 mL/kg bolus

›Reassess after each bolus

›Repeat as needed based on perfusion and urine output

›Analgesia and antipyresis

›Acetaminophen

›15 mg/kg PO q6h PRN

›Maximum 60 mg/kg/day

›Adult maximum 3000 mg/day when outpatient

›Ibuprofen

›10 mg/kg PO q6h to q8h PRN

›Maximum 40 mg/kg/day

›Adult maximum 2400 mg/day OTC aligned dosing

›Avoid acetaminophen overdose in hepatitis

›Use lowest effective dose

›Review combination cold products

Corticosteroids and escalation therapies

›Steroids are not routine for uncomplicated infectious mononucleosis

›Evidence quality mixed and routine symptom benefit not established

›Use limited to severe complications

›Indications for corticosteroids

›Impending airway obstruction from tonsillar hypertrophy

›Dexamethasone 10 mg IV or IM once

›Pediatrics 0.6 mg/kg IV or IM once

›Maximum 10 mg

›Prednisone 40 to 60 mg PO daily for 3 to 5 days as alternative

›Taper usually not required for short course

›Severe hemolytic anemia or severe thrombocytopenia

›Prednisone 1 mg/kg/day PO

›Hematology consultation for duration and taper

›IVIG consideration if refractory thrombocytopenia

Antimicrobials and co infection

›Antibiotics only for proven bacterial co infection

›Group A streptococcal pharyngitis positive testing

›Penicillin V 500 mg PO BID for 10 days

›Pediatric dosing per weight based local standard

›Avoid in true penicillin allergy

›Cephalexin 500 mg PO BID for 10 days if non anaphylactic penicillin allergy

›Avoid if immediate hypersensitivity history

›Azithromycin 500 mg PO day 1 then 250 mg PO daily days 2 to 5 if anaphylactic beta lactam allergy

›Local resistance considerations

›QT risk review

›Avoid aminopenicillins in suspected EBV infection

›Amoxicillin associated rash common in EBV

›Rash is not reliably a true IgE mediated allergy

Activity restriction and prevention

›Splenic rupture risk mitigation

›No contact sports and no collision activities for at least 3 weeks from symptom onset

›Longer restriction if persistent symptoms

›Shared decision making for return to play

›Avoid heavy lifting during early illness

›Increased intraabdominal pressure risk

›Gradual return with symptom guided progression

›Transmission reduction

›Avoid sharing drinks and utensils

›Avoid kissing while symptomatic and early convalescence

09Special Populations/sp23

Pregnancy

›Pregnancy considerations

›EBV infection not typically associated with congenital syndrome

›Symptom based supportive care remains standard

›Avoid unnecessary imaging and medications

›Medication safety

›Acetaminophen preferred for fever and pain

›NSAIDs avoidance in later pregnancy per obstetric guidance

›Abdominal pain differential broadened

›Ectopic pregnancy

›Placental complications if later gestation

Geriatric

›Older adult features

›Less prominent pharyngitis and lymphadenopathy

›Higher likelihood of jaundice and hepatitis pattern

›Risk and management considerations

›Broader malignancy evaluation if persistent lymphadenopathy

›Lower threshold for admission with dehydration and frailty

Pediatrics

›Pediatric presentation

›Often milder or atypical symptoms in younger children

›Adolescents resemble adult presentation

›Pediatric management

›Weight based dosing for analgesics and steroids

›Sports restriction counseling for school athletics

›Airway monitoring for significant tonsillar hypertrophy

10Background/b30

Epidemiology

›Frequency and transmission

›EBV is common worldwide and transmitted via saliva

›Infectious mononucleosis most common in adolescents and young adults

›Coding alignment

›ICD-10 infectious mononucleosis

›B27.0 gammaherpesviral mononucleosis without complication

›B27.9 infectious mononucleosis unspecified

›SNOMED CT concept

›Infectious mononucleosis

Pathophysiology

›Mechanism

›EBV infection of B lymphocytes with host immune response

›Atypical lymphocytes reflect reactive CD8 T cell response

›Organ involvement

›Lymphoid tissue hyperplasia

›Tonsillar enlargement

›Lymphadenopathy

›Splenic enlargement from lymphoid hyperplasia

›Rupture risk highest early in illness

›Hepatic involvement with mild hepatitis

›Transaminase elevation common

Therapeutic Considerations

›Treatment principles

›Supportive care is mainstay

›Corticosteroids reserved for severe complications

›Evidence and guideline style statements

›Routine antibiotics provide no benefit without bacterial co infection

›ACEP Level C consensus aligned

›Antimicrobial stewardship principle

›Activity restriction is recommended to reduce splenic rupture risk

›Class I recommendation based on expert consensus

›Imaging based clearance is limited by poor correlation with rupture risk

11Patient Discharge Instructions/pdi20

copy discharge instructions

›Home care

›Rest and fluids

›Acetaminophen or ibuprofen as directed on the label or by clinician

›Avoid alcohol while liver enzymes are elevated or while symptomatic

›Contagion reduction

›Avoid kissing and sharing drinks or utensils while sick

›Hand hygiene

›Activity restriction

›No contact sports or collision activities for at least 3 weeks from symptom onset

›No heavy lifting during early recovery

›Return to sports only when feeling well and cleared if required by team or school

›Return to ED now for

›Trouble breathing or noisy breathing

›Drooling or inability to swallow liquids

›Severe worsening throat pain or trismus

›Fainting or severe dizziness

›New severe abdominal pain or left shoulder pain

›Chest pain

›Uncontrolled bleeding or widespread bruising

›Severe headache, neck stiffness, confusion, or weakness

12References/r13

Clinical guidelines and society statements

›Core guidance sources

›CDC Epstein-Barr virus and infectious mononucleosis clinical overview

›AAP Red Book sections on EBV and infectious mononucleosis

›IDSA principles for pharyngitis testing and antibiotic stewardship

›Evidence grading mapping for this reference

›ACEP Level C used for consensus based ED practice where high quality trials are limited

›Class I used for broadly accepted safety critical recommendations

Evidence based reviews

›Diagnostic testing reviews

›Heterophile antibody testing performance varies by illness duration and age

›EBV specific serology for heterophile negative cases with high clinical suspicion

›Complication literature

›Splenic rupture is uncommon but highest risk early in illness

›Steroids reserved for airway compromise and severe hematologic complications

Learn More: Infectious mononucleosis→

Comprehensive Clinical Review

Structured, evidence-informed, long-form analysis for deeper understanding.

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.