Zanamivir (By breathing)

Zanamivir (zan-AM-i-vir)

Treats and helps prevent the flu (influenza type A and B).

Brand Name(s):


There may be other brand names for this medicine.

When This Medicine Should Not Be Used:

You should not use this medicine if you have had an allergic reaction to zanamivir, lactose, or milk proteins.

How to Use This Medicine:


  • Your doctor will tell you how much medicine to use. Do not use more than directed.
  • Start using this medicine as soon as possible after flu symptoms begin or after you are exposed to the flu (within the first 2 days).
  • Read and follow the patient instructions that come with this medicine. Talk to your doctor or pharmacist if you have any questions.
  • Relenza® is a powder that is used with its own inhaler device called a Diskhaler®. Individual doses of the powder are held in a foil blister pack called a Rotadisk®. Each Rotadisk® is placed into the Diskhaler®. The Diskhaler® pierces 1 blister at a time to load the correct dose when you are ready to use the medicine. An adult needs to watch closely while a child uses the Diskhaler®.
  • Do not use this medicine with a nebulizer. It should only be used with the Diskhaler® device that is included in the package.
  • Take all of the medicine in your prescription to clear up your infection, even if you feel better after the first few doses.

If a dose is missed:

  • Take a dose as soon as you remember. If it is almost time for your next dose, wait until then and take a regular dose. Do not take extra medicine to make up for a missed dose. If you miss a dose or forget to use it, use it as soon as you can if it is more than 2 hours before your next dose. Wait and use your next dose at the normal time if it is less than 2 hours before your next dose. Do not use extra medicine to make up for a missed dose.

How to Store and Dispose of This Medicine:

  • Keep the medicine in the foil pouch until you are ready to use it. Store at room temperature, away from heat and direct light. Do not freeze. Do not break the foil on the Rotadisk®.
  • Ask your pharmacist, doctor, or health caregiver about the best way to dispose of the used medicine container and any leftover medicine. You will also need to throw away old medicine after the expiration date has passed.
  • Keep all medicine out of the reach of children. Never share your medicine with anyone.

Drugs and Foods to Avoid:

Ask your doctor or pharmacist before using any other medicine, including over-the-counter medicines, vitamins, and herbal products.

  • Make sure your doctor knows if you plan to get the nasal flu vaccine (FluMist®). You should not receive the vaccine within 2 weeks before or 48 hours after you use this medicine.

Warnings While Using This Medicine:

  • Make sure your doctor knows if you are pregnant or breastfeeding or if you have heart disease, lung disease (such as asthma or COPD), or a history of seizures or mental illness.
  • This medicine does not take the place of a yearly flu shot. It will not keep you from getting a bacterial infection that causes flu-like symptoms.
  • This medicine may cause bronchospasm in people with lung disease (such as asthma or COPD). Stop using this medicine and call your doctor right away if you have trouble breathing, wheezing, or tightness in your chest after you use this medicine.
  • This medicine may cause changes in behavior. Tell your doctor if you have trouble sleeping, get upset easily, or have any unusual thoughts or behaviors. Also tell your doctor if you feel nervous, angry, restless, violent, or scared.
  • Do not use this medicine to treat other types of flu. Other people can still catch the flu from you even though you feel better while you use this medicine.
  • If you also use an asthma medicine that you inhale (such as albuterol, Atrovent®, Combivent®, or Serevent®), use it before you use zanamivir.
  • Call your doctor if your symptoms do not improve or if they get worse.
  • Your doctor will check your progress and the effects of this medicine at regular visits. Keep all appointments.

Possible Side Effects While Using This Medicine:

Call your doctor right away if you notice any of these side effects:

  • Allergic reaction: Itching or hives, swelling in your face or hands, swelling or tingling in your mouth or throat, chest tightness, trouble breathing
  • Confusion, anxiety, or changes in mood or behavior
  • Seeing, hearing, or feeling things that are not there
  • Seizures
  • Trouble breathing, wheezing, cough, or tightness in your chest

If you notice other side effects that you think are caused by this medicine, tell your doctor

Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088

Last Updated: 11/6/2020

The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites.

All rights reserved

A.D.A.M. content is best viewed in IE9 or above, Firefox and chrome browser.