Skip to main content

Main menu

  • Home
  • Articles
    • Current
    • Published Ahead of Print
    • Archive
    • Supplemental Issues
    • Collections - French
    • Collections - English
  • Info for
    • Authors & Reviewers
    • Submit a Manuscript
    • Advertisers
    • Careers & Locums
    • Subscribers
    • Permissions
  • About CFP
    • About CFP
    • About the CFPC
    • Editorial Advisory Board
    • Terms of Use
    • Contact Us
  • Feedback
    • Feedback
    • Rapid Responses
    • Most Read
    • Most Cited
    • Email Alerts
  • Blogs
    • Latest Blogs
    • Blog Guidelines
    • Directives pour les blogues
  • Mainpro+ Credits
    • About Mainpro+
    • Member Login
    • Instructions
  • Other Publications
    • http://www.cfpc.ca/Canadianfamilyphysician/
    • https://www.cfpc.ca/Login/
    • Careers and Locums

User menu

  • My alerts

Search

  • Advanced search
The College of Family Physicians of Canada
  • Other Publications
    • http://www.cfpc.ca/Canadianfamilyphysician/
    • https://www.cfpc.ca/Login/
    • Careers and Locums
  • My alerts
The College of Family Physicians of Canada

Advanced Search

  • Home
  • Articles
    • Current
    • Published Ahead of Print
    • Archive
    • Supplemental Issues
    • Collections - French
    • Collections - English
  • Info for
    • Authors & Reviewers
    • Submit a Manuscript
    • Advertisers
    • Careers & Locums
    • Subscribers
    • Permissions
  • About CFP
    • About CFP
    • About the CFPC
    • Editorial Advisory Board
    • Terms of Use
    • Contact Us
  • Feedback
    • Feedback
    • Rapid Responses
    • Most Read
    • Most Cited
    • Email Alerts
  • Blogs
    • Latest Blogs
    • Blog Guidelines
    • Directives pour les blogues
  • Mainpro+ Credits
    • About Mainpro+
    • Member Login
    • Instructions
  • RSS feeds
  • Follow cfp Template on Twitter
Research ArticlePractice

Antiviral medications for influenza

Christina Korownyk, Scott Garrison and Michael R. Kolber
Canadian Family Physician April 2015, 61 (4) 351;
Christina Korownyk
Associate Professor in the Department of Family Medicine at the University of Alberta in Edmonton.
  • Find this author on Google Scholar
  • Find this author on PubMed
  • Search for this author on this site
Scott Garrison
Associate Professor in the Department of Family Medicine at the University of Alberta in Edmonton.
  • Find this author on Google Scholar
  • Find this author on PubMed
  • Search for this author on this site
Michael R. Kolber
Associate Professor in the Department of Family Medicine at the University of Alberta in Edmonton.
  • Find this author on Google Scholar
  • Find this author on PubMed
  • Search for this author on this site
  • Article
  • eLetters
  • Info & Metrics
  • PDF
Loading

Clinical question

Do the neuraminidase inhibitors (NIs) oseltamivir or zanamivir improve clinical outcomes in influenza?

Bottom line

Biased, poor-quality, mostly unpublished evidence suggests that oseltamivir and zanamivir shorten the duration of influenza symptoms by 0.6 to 0.7 of a day. Pneumonia and hospitalizations are not decreased.

Evidence

Three 2014 systematic reviews of placebo-controlled RCTs (including > 160 000 pages of previously unreleased clinical study reports)1–3 found the following when treating otherwise healthy adults with influenza or influenzalike illness with oseltamivir (11 RCTs)1,2 or zanamivir (14 RCTs)1,3:

  • Time to symptom improvement was 0.6 to 0.7 days (about 10%) better1–3; the benefit of zanamivir was similar to “relief medications” (like acetaminophen).1,3

  • There was no benefit for pneumonia (x-ray scan confirmed)1–3 and hospitalizations were not reported1,3 or there was no benefit.1,2

  • Adverse events included the following:

    • -For oseltamivir,1,2 the number need to harm was 28 for nausea and 22 for vomiting.

    • -Postmarketing surveillance reports (frequency unknown) identified bronchospasm with zanamivir4 and delirium and self-injury with oseltamivir.5

A 2015 systematic review6 concluded adults receiving oseltamivir had faster symptom alleviation, and fewer lower respiratory tract complications and hospitalizations.

  • The review used similar studies1,2 but the conclusion was based on a subgroup with documented influenza.

  • The review was funded by, and 2 authors had pre-existing financial affiliations with, the manufacturer of oseltamivir.

From 26 systematic reviews,7 authors with financial conflicts of interest were 5 times more likely to report benefits of NI use (this includes a systematic review of cohort studies from the 2009–2010 pandemic suggesting that NIs decreased mortality in hospitalized patients8) and less likely to report on publication bias and the quality of included studies.

  • Other concerns1: unpublished protocols; inconsistent outcome definition; “placebos” with potential adverse effects; and incomplete reporting (eg, missing symptom cards).

Context

  • Oseltamivir sales are > $18 billion, half from government and company stockpiling. Most have not been used.9

  • The NIs are not recommended if symptoms have lasted longer than 48 hours.4,5 Zanamivir is contraindicated in asthma and COPD.4 There is limited evidence for oseltamivir in underlying cardiac or respiratory disease.5

  • Limited data suggest NIs are likely safe in pregnancy,10 but the manufacturers do not recommend (zanamivir)4 or conclude that there are insufficient data and to use them only when the potential benefit justifies the potential risk to the fetus (oseltamivir).5

Implementation

Headache or muscle aches do not reliably differentiate influenza from other respiratory infections. Cough with fever might have the greatest diagnostic value,11 but knowledge of current local influenza rates is more important. In outbreaks, 79% of patients with fever and cough have influenza,12 but influenza accounts for only 10% of identified respiratory pathogens in a typical winter.13 Trials of NIs generally exclude the very young, the old, and those with comorbidity. Targeting those at greatest risk of complications during influenza outbreaks might provide greater utility. High-quality trials enrolling such patients are needed.

Notes

Tools for Practice articles in Canadian Family Physician (CFP) are adapted from articles published on the Alberta College of Family Physicians (ACFP) website, summarizing medical evidence with a focus on topical issues and practice-modifying information. The ACFP summaries and the series in CFP are coordinated by Dr G. Michael Allan, and the summaries are co-authored by at least 1 practising family physician and are peer reviewed. Feedback is welcome and can be sent to toolsforpractice{at}cfpc.ca. Archived articles are available on the ACFP website: www.acfp.ca.

Footnotes

  • The opinions expressed in Tools for Practice articles are those of the authors and do not necessarily mirror the perspective and policy of the Alberta College of Family Physicians.

  • Copyright© the College of Family Physicians of Canada

References

  1. 1.↵
    1. Jefferson T,
    2. Jones MA,
    3. Doshi P,
    4. Del Mar CB,
    5. Hama R,
    6. Thompson MJ,
    7. et al
    . Neuraminidase inhibitors for preventing and treating influenza in healthy adults and children. Cochrane Database Syst Rev 2014;(4):CD008965.
  2. 2.↵
    1. Jefferson T,
    2. Jones M,
    3. Doshi P,
    4. Spencer EA,
    5. Onakpoya I,
    6. Heneghan CJ
    . Oseltamivir for influenza in adults and children: systematic review of clinical study reports and summary of regulatory comments. BMJ 2014;348:g2545.
    OpenUrlAbstract/FREE Full Text
  3. 3.↵
    1. Heneghan CJ,
    2. Onakpoya I,
    3. Thompson M,
    4. Spencer EA,
    5. Jones M,
    6. Jefferson T
    . Zanamivir for influenza in adults and children: systematic review of clinical study reports and summary of regulatory comments. BMJ 2014;348:g2547.
    OpenUrlAbstract/FREE Full Text
  4. 4.↵
    Relenza. Mississauga, ON: GlaxoSmithKline Inc; 2012. [product monograph].
  5. 5.↵
    Tamiflu. Mississauga, ON: Hoffmann-La Roche Ltd; 2014. [product monograph].
  6. 6.↵
    1. Dobson J,
    2. Whitley RJ,
    3. Pocock S,
    4. Monto AS
    . Oseltamivir treatment for influenza in adults: a meta-analysis of randomised controlled trials. Lancet 2015 Jan 30. Epub ahead of print.
  7. 7.↵
    1. Dunn AG,
    2. Arachi D,
    3. Hudgins J,
    4. Tsafnat G,
    5. Coiera E,
    6. Bourgeois FT
    . Financial conflicts of interest and conclusions about neuraminidase inhibitors for influenza: an analysis of systematic reviews. Ann Intern Med 2014;161:513-8.
    OpenUrlCrossRefPubMed
  8. 8.↵
    1. Muthuri SG,
    2. Venkatesan S,
    3. Myles PR,
    4. Leonardi-Bee J,
    5. Al Khuwaitir TS,
    6. Al Mamun A,
    7. et al
    . Effectiveness of neuraminidase inhibitors in reducing mortality in patients admitted to hospital with influenza A H1N1pdm09 virus infection: a meta-analysis of individual participant data. Lancet Respir Med 2014;2:395-404.
    OpenUrlCrossRefPubMed
  9. 9.↵
    1. Jack A
    . Tamiflu: “a nice little earner”. BMJ 2014;348:g2524.
    OpenUrlFREE Full Text
  10. 10.↵
    1. Dunstan HJ,
    2. Mill AC,
    3. Stephens S,
    4. Yates LM,
    5. Thomas SH
    . Pregnancy outcome following maternal use of zanamivir or oseltamivir during the 2009 influenza A/H1N1 pandemic: a national prospective surveillance study. BJOG 2014;121:901-6.
    OpenUrlPubMed
  11. 11.↵
    1. Monto AS,
    2. Gravenstein S,
    3. Elliott M,
    4. Colopy M,
    5. Schweinle J
    . Clinical signs and symptoms predicting influenza infection. Arch Intern Med 2000;160:3243-7.
    OpenUrlCrossRefPubMed
  12. 12.↵
    1. Boivin G,
    2. Hardy I,
    3. Tellier G,
    4. Maziade J
    . Predicting influenza infections during epidemics with use of a clinical case definition. Clin Infect Dis 2000;31:1166-9.
    OpenUrlAbstract/FREE Full Text
  13. 13.↵
    1. Nicholson KG,
    2. Kent J,
    3. Hammersley V,
    4. Cancio E
    . Acute viral infections of upper respiratory tract in elderly people living in the community: comparative, prospective, population based study of disease burden. BMJ 1997;315:1060-4.
    OpenUrlAbstract/FREE Full Text
PreviousNext
Back to top

In this issue

Canadian Family Physician: 61 (4)
Canadian Family Physician
Vol. 61, Issue 4
1 Apr 2015
  • Table of Contents
  • About the Cover
  • Index by author
Print
Download PDF
Article Alerts
Sign In to Email Alerts with your Email Address
Email Article

Thank you for your interest in spreading the word on The College of Family Physicians of Canada.

NOTE: We only request your email address so that the person you are recommending the page to knows that you wanted them to see it, and that it is not junk mail. We do not capture any email address.

Enter multiple addresses on separate lines or separate them with commas.
Antiviral medications for influenza
(Your Name) has sent you a message from The College of Family Physicians of Canada
(Your Name) thought you would like to see the The College of Family Physicians of Canada web site.
CAPTCHA
This question is for testing whether or not you are a human visitor and to prevent automated spam submissions.
Citation Tools
Antiviral medications for influenza
Christina Korownyk, Scott Garrison, Michael R. Kolber
Canadian Family Physician Apr 2015, 61 (4) 351;

Citation Manager Formats

  • BibTeX
  • Bookends
  • EasyBib
  • EndNote (tagged)
  • EndNote 8 (xml)
  • Medlars
  • Mendeley
  • Papers
  • RefWorks Tagged
  • Ref Manager
  • RIS
  • Zotero
Respond to this article
Share
Antiviral medications for influenza
Christina Korownyk, Scott Garrison, Michael R. Kolber
Canadian Family Physician Apr 2015, 61 (4) 351;
Reddit logo Twitter logo Facebook logo Mendeley logo
  • Tweet Widget
  • Facebook Like
  • Google Plus One

Jump to section

  • Article
    • Clinical question
    • Bottom line
    • Evidence
    • Context
    • Implementation
    • Notes
    • Footnotes
    • References
  • Info & Metrics
  • eLetters
  • PDF

Related Articles

  • No related articles found.
  • PubMed
  • Google Scholar

Cited By...

  • Vitamin D for influenza
  • Google Scholar

More in this TOC Section

Practice

  • Determining if and how older patients can safely stay at home with additional services
  • Managing type 2 diabetes in primary care during COVID-19
  • Effectiveness of dermoscopy in skin cancer diagnosis
Show more Practice

Tools for Practice

  • Bronchodilators or inhaled corticosteroids for postinfectious cough
  • Intrauterine devices for menorrhagia
  • Topical treatments for anal fissure
Show more Tools for Practice

Similar Articles

Navigate

  • Home
  • Current Issue
  • Archive
  • Collections - English
  • Collections - Française

For Authors

  • Authors and Reviewers
  • Submit a Manuscript
  • Permissions
  • Terms of Use

General Information

  • About CFP
  • About the CFPC
  • Advertisers
  • Careers & Locums
  • Editorial Advisory Board
  • Subscribers

Journal Services

  • Email Alerts
  • Twitter
  • RSS Feeds

Copyright © 2023 by The College of Family Physicians of Canada

Powered by HighWire