Neuraminidase inhibitor (antiviral)
Zanamivir
Brand names: Relenza
Adult dose
Dose: Treatment: 10mg (2 inhalations) BD for 5 days; Prophylaxis: 10mg OD for 10 days
Route: Inhaled (Diskhaler)
Frequency: BD (treatment) / OD (prophylaxis)
Clinical pearls
- Start within 48 hours of symptom onset for greatest benefit
- NICE NG34: prophylaxis in at-risk contacts during influenza outbreaks
- Caution in asthma/COPD — have bronchodilator to hand
- IV formulation available for critically ill (via specialist access)
Contraindications
- Hypersensitivity
- Severe reactive airways disease (relative — bronchospasm risk)
Side effects
- Bronchospasm (especially in asthma/COPD)
- Headache
- Dizziness
- GI disturbance
- Rash
- Neuropsychiatric events (rare, class effect)
Interactions
- Live attenuated influenza vaccine (do not give within 2 days)
Monitoring
- Respiratory function (asthma/COPD patients)
- Symptom resolution
Reference: BNF; NICE NG34; UKHSA influenza guidance; https://bnf.nice.org.uk/drugs/zanamivir/. Verify against your local formulary and the latest BNF before prescribing.
Related
Curated clinical cross-links plus same-class fallbacks.
Calculators
- SMART Risk Score for Recurrent CVD · Cardiovascular Risk
- PCSK9 Inhibitor Eligibility Assessment · Lipid Management
- Immune-Related Adverse Events (irAE) -- GI Toxicity Colitis Grading · Oncology-Related GI
- irAE Hepatitis Grading (CTCAE) · Immunotherapy
- DIPSS — Dynamic International Prognostic Scoring System for Myelofibrosis · Cancer Prognosis
- BALL Score for Relapsed/Refractory CLL · Leukaemia
Pathways
- Infective Endocarditis · ESC 2023 Infective Endocarditis Guidelines; NICE NG41
- Eczema Herpeticum · BAD; NICE CKS
- Suspected Bacterial Meningitis (Adult) · NICE NG240 (2024); NICE NG143 (paeds)
- Clostridioides difficile Colitis · NICE NG199 (2021); IDSA/SHEA 2021
- Returning Traveller — Fever · NaTHNaC; PHE; ESCMID 2018
- Malaria — Diagnosis & Management · PHE 2016; WHO 2023