Guidelines for Reporting Suspected Adverse Reactions to Antiviral Medicines an Influenza Pandemic

Notice type: Advisory

Date: 15/05/2009


Product name or type:
Antiviral Medicines

Problem Or Issue:
Anti-viral medicines are used for the early treatment and prevention of influenza infection. Pending the availability of virus-specific vaccines two medicines oseltamivir (Tamiflu®) and zanamivir (Relenza®) are expected to be widely used in the event of an influenza pandemic with influenza A(H1N1). These medicines when taken early in the illness (within 48 hours) can both shorten the duration of infection and reduce the serious complications of influenza. 
Antiviral medicines may also prevent influenza infection if they are taken during periods of potential exposure to the virus. Detailed guidance for use of anti-viral medicines in an influenza pandemic is provided by the Pandemic Influenza Expert Group, which is available on the Health Protection Surveillance Centre website at 

Why Report Adverse Reactions to Antiviral Medicines during a Pandemic? 

To date serious adverse reactions to these antiviral medicines have been very rare. However no medicinal products are risk free and as their usage increases, more information about the safety profile of antiviral medicines is expected to become available. If new safety concerns are identified, the Irish Medicines Board (IMB) will work with its EU counterparts to establish appropriate risk minimisation measures to support the continued safe and effective use of these medicines. The prompt identification of a safety concern during a pandemic will rely on the detection and reporting of adverse reactions to the IMB. 
During a pandemic it will be particularly important to identify and respond to any serious adverse reactions, as this information will help guide the safest and most effective use of these medicines. During an influenza pandemic the IMB together with its international counterparts will make the assessment of reports of suspected adverse reactions to antiviral medicines a priority, to ensure that any new safety concerns are managed appropriately, with information communicated as quickly as possible to ensure the continued safe and effective use of these products. 

What to report? 

All suspected adverse reactions should be reported. It is of particular importance that serious adverse reactions should be notified promptly, including cases where an antiviral medicine is thought to have been ineffective. In addition, information on any patients treated with antiviral medicines during pregnancy should also be notified. 

To assist the IMB in the assessment of suspected adverse reactions, as much information as possible should be provided in the initial report, particularly the following information if available: 

• the age and gender of the patient 
• the medical history, including any previously diagnosed/recently diagnosed conditions 
• any concomitant medications, whether prescription or over the counter medicines 
• the description, diagnosis, treatment and outcome of the reaction 
• whether the anti-viral medicine was used for prevention or treatment of influenza
• if the anti-viral medicine was discontinued. 

How to report? 

The most efficient way to report adverse reactions to the IMB in a pandemic situation is via our online reporting system at

    1. On-line at and follow the links to ‘On-line Reporting’ to complete a Human Medicines Adverse Reaction Report 

    2. ‘Freepost system’ – Adverse Reaction Report Forms (yellow cards) can be obtained directly from the Pharmacovigilance Unit of the IMB or downloaded from the website under the ‘Publications section’. A supply of yellow cards/Adverse Reaction Report Forms may be requested by telephoning the Pharmacovigilance Unit of the IMB at 01-676 4971 

For oseltamivir (Tamiflu®) and zanamivir (Relenza®) product information, please click on the following links:

Click here for Further information on Relenza

Click here for Further information on Tamiflu

Updated safety information for oseltamivir (Tamiflu®) and zanamivir (Relenza®) will be published as necessary on the website at and on the European Medicines Agency website at

Please use the contact details below with any queries you may have in relation to the reporting of adverse reactions: 

Pharmacovigilance Section, 
Health Products Regulatory Authority, 
Kevin O'Malley House, 
Earlsfort Centre, 
Earlsfort Terrace, 
Dublin 2, 

Tel: 353-1-676 4971 
Fax: 353-1-634 3514 

« Back