Influenza Treatment (Antimicrobial)


What's New:
Severely immunosuppressed patients should also get oseltamivir first line. Zanamivir is only used if the dominant circulating strain is likely to be oseltamivir resistant.
See the full document for dosing in renal impairment and guidelines for using IV zanamivir.

Annual vaccination is essential for all those at risk of influenza. See Public Health Scotland recommendations for Treatment and Prophylaxis of Influenza. For otherwise healthy adults, antivirals are NOT recommended.

Treat ‘at risk’ patients, only when influenza is circulating in the community and ideally within 48 hours of onset, or in a care home where influenza is likely.

At risk:

  • 65 years or over
  • Chronic respiratory disease (including COPD and asthma)
  • Significant cardiovascular disease (not hypertension)
  • Immunocompromised
  • Diabetes mellitus
  • Chronic neurological, renal or liver disease
  • Seek advice for patients under 13 years and pregnant women.
  • Reduce dose in renal impairment (see national guidance or seek advice from Pharmacy)


Intravenous zanamivir should only be used if the patient is unable to adequately absorb oral oseltamivir or use inhaled zanamivir. See manufacturer's information for dosing in adults, children aged 6 years and over and in renal impairment.

For glossary of terms see Glossary.

Drug details

Treatment of influenza, including severe immunosuppression

Oseltamivir 75mg twice daily

5 days (10 days for immunocompromised)

If resistance to oseltamivir 

Zanamivir (inhaled) 10mg twice daily

5 days

Prophylaxis of influenza

Oseltamivir 75mg once daily

10 days

Prophylaxis of influenza if resistance to oseltamivir

Zanamivir (inhaled) 10mg once daily

10 days

Last reviewed: 23/12/2022

Next review date: 31/12/2024

Author(s): Antimicrobial Management Team.

Version: V1.2

Approved By: Awaiting approval by the TAM Subgroup of ADTC

Reviewer name(s): Alison Macdonald, Area Antimicrobial Pharmacist.

Document Id: AMT152