AKT · ENT/Throat & airwaylow yield

Infectious mononucleosis (glandular fever)

Epstein-Barr virus (EBV) infection

Overview

A systemic EBV infection of adolescents/young adults presenting with a severe sore throat, gross tonsillar enlargement, marked malaise and lymphadenopathy — the key tonsillitis mimic. Two exam essentials: it causes a florid rash if given amoxicillin/ampicillin, and splenomegaly means avoiding contact sport (splenic rupture).

Recognise

Adolescent/young adult with severe sore throat, gross (sometimes confluent, exudative) tonsillar enlargement, fever and profound fatigue/malaise
Widespread tender lymphadenopathy (esp. posterior cervical), palatal petechiae, and SPLENOMEGALY ± hepatomegaly
Transmitted in saliva ("kissing disease"); fatigue can persist for weeks

Red flags

SPLENOMEGALY → risk of splenic rupture (avoid contact sport for ~4–6 weeks); rarely airway compromise from massive tonsils; jaundice/hepatitis

Differentials & how to tell them apart

Streptococcal tonsillitisno marked splenomegaly/atypical lymphocytes; responds to penicillin — glandular fever has profound malaise, posterior nodes, splenomegaly and an EBV-positive serology

CMV/toxoplasma/acute HIVa mono-like illness — test if Monospot negative and features atypical

Lymphoma/leukaemiapersistent lymphadenopathy/cytopenias — blood film + haematology

Quinsyunilateral trismus + uvular deviation

Investigations

FBC (lymphocytosis with ATYPICAL lymphocytes) + heterophile antibody test (Monospot) — may be falsely negative in the first week → EBV-specific serology (VCA IgM) if needed; LFTs (often deranged).

Management

Supportive care + avoid contact sport while splenomegaly persists; NO amoxicillin

1Diagnose (atypical lymphocytes + Monospot/EBV serology) and treat supportively — it is self-limiting. Advise on prolonged fatigue.Gate: Do NOT give amoxicillin/ampicillin (florid rash in EBV), and ADVISE AVOIDING contact sport / heavy lifting for ~4–6 weeks while splenomegaly persists (splenic-rupture risk) — these two safety points are the exam essence
2Airway compromise from massive tonsils → corticosteroids ± ENT; persistent symptoms → reassess for complications (hepatitis, haematological).

Supportive care (rest, fluids, analgesia) — self-limiting — the mainstay

AVOID amoxicillin/ampicillin — causes a florid maculopapular rash in EBV infection

Corticosteroids — reserved for airway compromise from massive tonsillar swelling (specialist)

Key points

The amoxicillin-rash trap and the contact-sport/splenic-rupture advice are the two high-yield points. Posterior cervical nodes + splenomegaly + atypical lymphocytes separate it from strep tonsillitis. (Also belongs on a future Infection page — cross-reference, don't duplicate.)

Monitor & prognosis

Resolution over weeks; splenomegaly before return to sport; LFTs if deranged.

Self-limiting; fatigue can linger; complications are uncommon.

Source: NICE CKS Glandular fever (infectious mononucleosis)