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Educational draft · awaiting clinical reviewUse Rapid for revision, not patient-care decisions. Check current national and local guidance and the BNF or BNFC before acting.

Viral meningitis

Neurology · UK scope · Sources checked 27 Aug 2026 · Clinical review pending

RapidFull
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Escalate

Acute meningitis cannot be labelled viral from symptoms alone. Treat shock, purpura, reduced consciousness, focal neurology, seizures or rapidly progressive illness as possible bacterial meningitis, encephalitis or another intracranial emergency. Start empirical antibacterial therapy according to the emergency pathway whenever bacterial disease has not been safely excluded.

Synopsis

Diagnose aseptic meningitis without prematurely withholding antibacterial treatment, identify viral causes needing targeted therapy or public-health action, and give realistic recovery and safety-net advice.

  • Viral meningitis presents with fever, headache, photophobia, neck stiffness, nausea and malaise, usually with preserved or only mildly altered cognition; substantial encephalopathy suggests encephalitis or severe systemic disease.
  • Enteroviruses are frequent causes, while herpes simplex virus type 2, varicella-zoster virus, acute HIV, mumps and travel-related arboviruses become relevant in the right exposure context.
  • Clinical appearance and cerebrospinal-fluid lymphocytes do not immediately exclude bacterial meningitis, because early viral infection may be neutrophilic and partially treated bacterial disease may become lymphocytic.
  • Take blood cultures and give empirical antibacterial treatment first when indicated; lumbar puncture should follow promptly when it is safe and does not create treatment delay.
  • Typical cerebrospinal fluid has a lymphocytic pleocytosis, normal glucose ratio and moderately raised protein, but interpretation must integrate timing, immune status and prior antimicrobials.
  • Request targeted cerebrospinal-fluid PCR according to the syndrome and season rather than an indiscriminate panel whose low-prevalence positives may mislead.
  • Marked confusion, personality change, aphasia, focal seizures or temporal-lobe abnormalities should trigger an encephalitis pathway and immediate intravenous aciclovir, not reassurance about viral meningitis.
  • Antiviral treatment is not routine for uncomplicated enteroviral meningitis; HSV, VZV or immunocompromised disease requires infection-specialist advice on intravenous or oral therapy.
  • Most immunocompetent adults recover with fluids, antiemetics, analgesia and graded activity, although headache, fatigue, poor concentration and sleep disturbance can persist for weeks.
  • Explain hand hygiene and pathogen-specific precautions and offer HIV testing when appropriate. In England, every suspected acute meningitis case is notifiable urgently by telephone within 24 hours and online within 3 days; report on suspicion rather than waiting to identify a pathogen, using equivalent devolved-nation routes elsewhere.

Key red flags

Encephalitic transition

Sustained altered behaviour, new focal deficit, dysphasia or seizure signifies brain involvement and requires urgent aciclovir and encephalitis investigation.

Investigation priorities

01
Blood cultures and acute blood profileFirst step

Preserve evidence of bacterial disease and identify organ dysfunction before treatment.

Management branches

Acute presentationTreat uncertainty as potentially bacterial

A patient presents with fever, headache and meningism.

  1. Assess ABCDE, consciousness, rash, focal neurology and seizures, taking blood cultures and urgent blood samples while initiating sepsis support where required.
  2. Give empirical antibacterial treatment and dexamethasone according to the bacterial-meningitis pathway whenever that diagnosis remains plausible; do not wait for a viral PCR.
  3. Perform lumbar puncture promptly if safe, sending cells, paired glucose, protein, culture and syndrome-directed PCR with enough retained sample for additional tests.
  4. At first clinical suspicion, report acute meningitis through the statutory health-protection route without waiting for cerebrospinal-fluid PCR, culture or serology.
Viral evidenceNarrow treatment after review

The patient is stable and cerebrospinal fluid or PCR supports a viral cause.

  1. Reconcile the fluid pattern, blood cultures, illness trajectory and pretreatment with microbiology before concluding bacterial infection is sufficiently excluded.
  2. Stop antibacterial therapy only through senior clinical and microbiology review, and decide whether HSV, VZV, HIV or host immunosuppression creates a targeted antiviral indication.

Key medicines

ParacetamolUse the current BNF adult oral regimen, reducing the maximum in low body weight, liver disease or other circumstances that increase toxicity risk.Check cold remedies and combination analgesics to prevent duplicate dosing; symptom improvement does not exclude bacterial disease or encephalitis.
Intravenous aciclovirWhen HSV or VZV encephalitis is possible, use the current BNF weight-based intravenous regimen, commonly 10 mg/kg every 8 hours, with renal adjustment and specialist oversight.Ensure hydration, infuse correctly and monitor creatinine because crystal nephropathy and neurotoxicity can occur; uncomplicated enterovirus meningitis does not benefit.
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Sources and review status5 sources · checked 27 Aug 2026 · clinical review pending+
Sources

Sources and review status

National guidance is shown before implementation-dependent detail. Typical adult dose examples remain subject to patient factors, contraindications and the live BNF or specialist protocol. Source check completed 27 Aug 2026; clinical approval remains outstanding.

  • NICE NG240 meningitis recommendationsSafe acute assessment while bacterial meningitis remains possible.
  • UK joint specialist-societies acute meningitis guidelineAdult bacterial and viral meningitis investigation, treatment and follow-up guidance; public-health reporting is sourced separately.
  • ABN/BIA national guideline for suspected viral encephalitis in adultsProfessional guidance for recognising encephalitis and starting time-critical empirical aciclovir.
  • BHIVA HIV testing guidelinesTesting strategy where acute HIV is a plausible cause of aseptic meningitis.
  • UKHSA notifiable diseases and reportingStatutory suspicion-based reporting, urgency and timescales for acute meningitis in England; use equivalent devolved-nation routes elsewhere.

Editorial contact: Doctor’s Passport editorial team. Source-check date is separate from clinical approval. Report a content problem · Content changes

Authoring stateRapid draftClinical stateAwaiting reviewJurisdictionUnited Kingdom
Provide oral hydration, antiemetic and simple analgesic support, avoiding unnecessary opioids and repeated lumbar puncture for a resolving uncomplicated illness.