H1N1 Flu Drugs and Patient Experience

Only two drugs were approved for treating 2009 Influenza A (Swine Flu or H1N1) virus: Tamiflu and Relenza. Both of these drugs are in a class of drugs called neuraminidase inhibitors (NAIs). Neuraminidase is a protein on the surface of an influenza virus that helps it spread the virus to other cells. NAIs can help stop that protein from infecting other cells. Both drugs can help shorten the duration of flu symptoms, such as fever, chills, muscle aches, headache, congestion, and cough. However, it is important that the drug treatment begin within 2 days of when the symptoms of the Flu begin.

This article provides an overview of what each drug does, where to get warnings and FDA information, and highlights and analysis of the ratings received for Tamiflu on Askapatient.com.

  • TAMIFLU (oseltamivir phosphate)by Roche Pharmaceuticals,
    is available as a capsule or in a liquid (oral suspension) formulation. The capsule form was approved by the FDA October 27, 1999, and the liquid formulation was approved December 14, 2000. Tamiflu is more frequently prescribed than Relenza and is approved for patients over the age of 1. This drug was widely used in 2005 during the avian flu outbreak in Japan and other parts of southeast Asia. When Tamiflu is used to treat flu symptoms, it is usually taken two times a day (morning and evening) for 5 days. When oseltamivir is used to prevent flu, it is usually taken once a day for at least 10 days, or for up to 6 weeks during a community flu outbreak.


Tamiflu users say side effects are common; more than one-third of patients report nausea.

The ratings coincide with the results of a study by UK’s Health Protection Agency, in which more than half of children in three London schools who took Tamiflu suffered side effects. In that study, forty percent had gastrointestinal problems, while nearly one in five experienced mild neuropsychiatric effects such as confusion, strange behavior and sleep problems.

(reported on Askapatient.com; age 12 and under; as of March 8, 2011)

Side Effect
Number of Patients
Percent of Patients
Gastrointestinal Problems (Nausea, Vomiting, Diarrhea)
Neuropsychiatric Side Effect* (Night terrors, Hallucinations, Confusion)
Skin Reaction/Rash, Itching, Swelling
*In 2008, the FDA issued a FDA safety alert with regarding pediatric patients, neuropsychiatric events, and use of Tamiflu and Relenza.

While the Tamiflu drug label says only 10% of adult flu patients and 15% of children aged 1-12 experienced nausea during clinical trials, more than one-third of Askapatient.com respondents reported suffering from nausea. Many users tell Askapatient.com the side effects led them to discontinue treatment.


In December 2012, the FDA approved Tamiflu for use in babies as young as 2 weeks of age. This applies to patients who have shown symptoms of flu for no longer than two days.See FDA Tamiflu announcement.
The average rating for Tamiflu for babies 1 years or less is 2.2 (less than somewhat satisfied)
Click here for Tamiflu reviews for children 1 year old or less .

Click here for updated (2018) article on side effects experienced by children taking Tamiflu: https://www.askapatient.com/news/scary-side-effects-nightmares-and-hallucinations-in-children-taking-tamiflu.asp

(771 respondents; all ages; as of March 8, 2011 to AskaPatient.com)

Side Effect
Number of Patients
Percent of Patients
Nausea and/or Vomiting
Rash, Blisters, Itching, Swelling
Night Terrors/Nightmares
Anxiety/Panic Attacks
Neuropsychiatric Events (Hallucinations and Psychotic Episodes)

Not all respondents told Askapatient.com, an independent forum for consumers, they were disappointed with Tamiflu. Out of 771 patients, 186 gave it 4 or 5—the two highest marks. Of these patients, most reported having mild side effects or no side effects at all.

The CDC revised their guidelines about who should be taking flu antivirals: only high-risk flu patients or flu patients being admitted to the hospital.

A recent study in the British Medical Journal found that Tamiflu provides a small benefit for children and shortens the duration of influenza by about a day. Such studies, along with the growing numbers of reports on side effects and benefits, can help doctors and flu patients decide on the best individual course of treatment.

To examine the Tamiflu ratings in detail, please see Askapatient's Tamiflu Drug Ratings Report.

Studies cited:

Eurosurveillance, Volume 14, Issue 30, 30 July 2009 Rapid communications Oseltamivir adherence and side effects among children in three London schools affected by influenza A(H1N1)v, May 2009 – an internet-based cross-sectional survey A Kitching ()1,2, A Roche3, S Balasegaram4, R Heathcock5, H Maguire3

British Journal of Medicine 10 August 2009, doi:10.1136/bmj.b3172 Neuraminidase inhibitors for treatment and prophylaxis of influenza in children: systematic review and meta-analysis of randomised controlled trials by Matthew Shun-Shin, , Matthew Thompson, Carl Heneghan, , Rafael Perera, , Anthony Harnden, , David Mant, Oxford University

  • RELENZA (zanamivir) by Glaxo Smithkline, is available as a powder to inhale (breathe in) by mouth. Zanamivir comes with a plastic inhaler called a Diskhaler (device for inhaling powder) and five Rotadisks (circular foil blister packs each containing four blisters of medication). It is only approved for patients over the age of 7. It was approved by the FDA July 26, 1999. Manufacturer information is at Relenza.com


Only a small number of ratings have been added to the database, so there is not enough data to analyze at this point. Relenza has an average rating of 4.6 as of October 22. The current report for Relenza can be found at Askapatient's Relenza Drug Ratings Report.

If you have tried Relenza, did it work or not? Please share your experience with other patients and contribute your rating at http://www.askapatient.com/ratingform.asp?drug=21036&name=RELENZA

Click here to view a video on how to use the inhaler

FDA information on Relenza Drug Label for Relenza

Medline information on Relenza: Zanamivir Inhalation

Some general information on Swine Flu, including what to do if you get flu-like symptoms, can be found at the Center for Disease Control at : http://www.cdc.gov/h1n1flu/general_info.htm

Find general influenza information at http://www.cdc.gov/flu/

Click here for Center for Disease Control's information on flu vaccinations.

Sources: Askapatient database, FDA web site, NIH's Medline web site, official FDA drug labels, Center for Disease Control sites -

The National Library of Medicine's Medline provides description of drug, common side effects, prescribing guidelines in easy-to-understand language.
Manufacturer's web site: Tamiflu.com.
Drug Labelfor liquid and capsule contains complete technical and prescribing information about the drug, including side effects reported during testing of the drug.
Basic FDA informationincludes approval history, letters.
PDF version (printable) of article released in October 2009 on Tamiflu