• Decrease font size
  • Return font size to normal
  • Increase font size
U.S. Department of Health and Human Services


  • Print
  • Share
  • E-mail

Relenza: Consumer Questions and Answers

Q.  What is Relenza and what is it approved for?

A. Relenza (zanamivir) is an antiviral drug.  It works by attacking the flu virus to keep it from multiplying in your body and reducing the symptoms of the flu. It can sometimes keep you from getting the flu if you take it before you get sick.  

The term "flu" refers to illness caused by the influenza virus. The flu is a respiratory infection that can cause symptoms such as fever, chills, aches and pains, cough, and sore throat. The flu can range from mild common cold symptoms, to the typical "flu" symptoms described above, to life-threatening pneumonia and other complications, including secondary bacterial infections.

Relenza is used to treat people 7 years of age and older who have the flu (influenza A and B viruses). Relenza is also sometimes used for prevention (prophylaxis) of the flu in people age 5 years or older, but it is not a substitute for getting the flu vaccine.

Q. Is Relenza a substitute for the flu vaccine?

A. No.  Getting the flu vaccine is the best way to protect against getting the flu and to control the spread of the flu.

Other important parts of avoiding flu include avoiding unnecessary close contact between sick and well people, covering coughs and sneezes, and washing hands frequently.

More information on flu vaccines and other flu control measures is available on the Flu.gov website.

Q. What do the terms treatment of the flu and prevention (prophylaxis) of the flu mean?

A. Treatment is used when a person is given Relenza because they have the signs and symptoms of the flu or have been diagnosed with the flu. Relenza has been shown to lessen the amount of time people are sick with the flu.

Prevention (prophylaxis) is a term used when someone who does not have flu symptoms is given Relenza to help stop them from getting the flu because they are exposed to or come into close contact with someone (for example live with or take care of someone) who has the flu.

Q.  Do I take Relenza the same way for treatment and prevention (prophylaxis) of the flu?

A. No. The number of times a day (frequency) and the number of days (duration) that you take Relenza are different for treatment and prevention (prophylaxis) of the flu. Your healthcare provider will tell you how to take Relenza. Take it exactly as your healthcare provider prescribes.

Q.  What should people do if they continue to have or start to develop flu symptoms while taking Relenza?

A. If flu symptoms do not go away, or if you get new symptoms while taking Relenza, people should contact their healthcare provider. Other illnesses may cause people to have symptoms similar to the flu, or may occur at the same time as the flu, and they might need other treatment.

Q. How is Relenza supplied?

A. Relenza is a powder that you inhale into your mouth using a device called a Diskhaler. The powder is in a pouch called a blister. There are 4 blisters on each circular medication pack (Rotadisks). Each blister contains 5 mg of medicine. Each box of Relenza contains five Rotadisks.

 Q. How many blisters are used for a dose?

A. Two (2) blisters are used for each dose.  The 4 blisters on the Rotadisk are enough medicine for 2 doses.  Your doctor will tell you how many times a day and for how many days you should take the medicine.

Q. Are there instructions for people who have never used an inhaler?

A. Yes, each box of Relenza has a Patient Instructions for Use leaflet that explains how to take Relenza using the Diskhaler device. These instructions are not a substitute for education and demonstration by your healthcare provider. Your healthcare provider will tell you how to use Relenza. Use it exactly as your healthcare provider prescribes. To help make sure Relenza is used the right way by children, it should be used only under adult supervision.  The supervising adult must understand how to use the Diskhaler device.

Q. Are there any other special instructions to remember?

A. Yes, it is important to remember to puncture both the top and bottom of the blister using the Diskhaler before inhaling the medication into your mouth.  Relenza should never be used with any other device but the Diskhaler. The blisters of medicine should never be opened and mixed into a liquid.

Q. Are there people who should not take Relenza?

A. Yes. Relenza is not for people who have chronic lung diseases such as asthma or chronic obstructive pulmonary disease (COPD). Also, since the Relenza powder contains lactose, people who have an allergy to lactose should not use Relenza.

Talk with your healthcare provider if you have concerns about using Relenza.

Q. Should women who are pregnant or nursing take Relenza?

A. Relenza may be of benefit for some pregnant and nursing women. At this time, the U.S. Centers for Disease Control and Prevention (CDC) recommends that pregnant women who are sick from influenza should be treated with a flu drug because of concerns that they could develop more serious illness.  Pregnant and nursing women are advised to talk with a healthcare professional before using Relenza.

More information is available at flu.gov (see http://www.flu.gov/individualfamily/parents/pregnant5tips.html).

Q. What are the most common side effects of Relenza?

A. The most common side effects of Relenza are:

  • diarrhea          
  • nausea
  • vomiting
  • headache
  • dizziness
  • nasal irritation
  • cough
  • ear, nose, and throat infections.

Q. What are the serious side effects of Relenza?

A. Some people have more trouble breathing while using Relenza, especially if you have chronic lung disease. If you have more trouble breathing after using Relenza, you should stop using Relenza and get medical help right away.

Children and teenagers with the flu may be at a higher risk for seizures, confusion, or abnormal behavior early during their illness. These serious side effects may happen shortly after beginning Relenza or may happen in people when the flu is not treated. These serious side effects are uncommon but may result in accidental injury to the patient. People who take Relenza should be watched for signs of unusual behavior and a healthcare provider should be contacted right away if a patient shows any unusual behavior while taking Relenza.

Rare cases of allergic reactions, including serious skin rashes, have happened in people who use Relenza. If a rash develops, stop Relenza and contact a healthcare provider right away.

Report any side effects and medication errors from Relenza to FDA at 1-800-FDA-1088.