Viral meningitis

Last reviewed: 28 Dec 2022
Last updated: 17 Jan 2023



History and exam

Key diagnostic factors

  • presence of risk factors
  • headache
  • photophobia
  • neck stiffness
  • fever
  • nausea and vomiting
Full details

Other diagnostic factors

  • rash
  • Kernig's sign
  • Brudzinski's sign
Full details

Risk factors

  • infants and young children
  • young adults
  • older people
  • summer and autumn
  • exposure to mosquito or tick vector
  • unvaccinated for mumps
  • use of swimming pools and ponds
  • communal living
  • immunosuppression
  • exposure to rodents
Full details

Diagnostic investigations

1st investigations to order

  • blood cultures
  • FBC and differential
  • C-reactive protein (CRP)
  • serum urea, creatinine, and electrolytes
  • blood gases
  • blood glucose
  • CSF microscopy
  • CSF Gram stain
  • CSF bacterial culture
  • CSF protein
  • CSF glucose
  • CSF lactate
  • CSF, stool and throat swab PCR for viral pathogens
  • HIV serology/HIV reverse transcriptase (RT)-PCR
Full details

Investigations to consider

  • CT/MRI head scan
Full details

Treatment algorithm


suspected meningitis, unknown aetiology


confirmed viral meningitis


recurrent viral meningitis


Expert advisers

John Williams, MRCP, DTM&H

Infectious Diseases Consultant

The James Cook University Hospital




JW declares that he has no competing interests.


Dr John Williams would like to gratefully acknowledge Dr David Chadwick, a previous contributor to this topic. DC is an author of a reference cited in this topic.

Peer reviewers

Alex Alexiou, MBBS, BSc, DCH, FRCEM, Dip IMC RCSEd

Consultant in Emergency Medicine

Royal London Hospital

Consultant, Physician Response Unit

Barts Health NHS Trust/London Air Ambulance




AA declares that he has no competing interests.

Fiona McGill, MRCP, DTMH, DipHIVMed

Clinical Lecturer

Institute of Infection and Global Health

University of Liverpool




FM is on the Meningitis Research Foundation’s Medical Advisory Group, has lectured on national and international events on meningitis and has developed a review for ‘clinical medicine’ on viral meningitis and encephalitis.


Tannaz Aliabadi-Oglesby

Lead Section Editor, BMJ Best Practice


TAO declares that she has no competing interests.

Rachel Wheeler

Lead Section Editor, BMJ Best Practice


RW declares that she has no competing interests.

Adam Mitchell

Drug Editor, BMJ Best Practice


AM declares that he has no competing interests.

Julie Costello

Comorbidities Editor, BMJ Best Practice


JC declares that she has no competing interests.

  • Differentials

    • Meningitis, bacterial
    • Encephalitis
    • Encephalopathy (toxic/metabolic)
    More Differentials
  • Guidelines

    • A guide to utilization of the microbiology laboratory for diagnosis of infectious diseases: 2018 update by the Infectious Diseases Society of America and the American Society for Microbiology
    • The UK joint specialist societies guideline on the diagnosis and management of acute meningitis and meningococcal sepsis in immunocompetent adults
    More Guidelines
  • Patient leaflets

    Meningitis and septicaemia

    Lumbar puncture

    More Patient leaflets
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