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Generic name: zanamivir [zan-AM-i-vir]
Brand name: Relenza
Dosage format: inhalation powder (5 mg)
Classification of drugs: inhaled anti-infectives, neuraminidase inhibitors

What is Zanamivir?

Zanamivir is a medicine for antiviral treatment that blocks the activities of the viruses that are present in your body.

Zanamivir is a drug used to treat influenza symptoms that are caused by the influenza virus in patients who have been suffering from symptoms for less than two days. Zanamivir can also be administered to help prevent the spread of influenza among people who are exposed but have not yet developed symptoms. Zanamivir is not a treatment for the common cold.

Zanamivir is not recommended to replace an annual influenza shot. It is recommended that you get a flu shot every year. The Centres for Disease Control recommend getting a flu shot every year to protect you from the emergence of new strains of influenza.Zanamivir can also be used to treat conditions not covered in this guide.

Side effects of Zanamivir

See a doctor immediately. If you are experiencing warning signs of an allergic response, such as symptoms of hives, difficulty breathing, or swelling of your lips, face, and tongue,

Certain people who are taking zanamivir (especially youngsters) have experienced an abrupt change in behavior or mood. It is not certain that zanamivir is the sole reason behind these symptoms. Even if zanamivir is not used, any person with influenza may be afflicted by behavioral or neurologic symptoms. Call your doctor immediately if the patient who is taking zanamivir experiences:

  • Sudden confusion;
  • Difficulty speaking;
  • Shaking or tremors;
  • A seizure;
  • Hallucinations (hearing the sounds of things or having visions that aren't actually there)

Stop taking zanamivir and consult your physician immediately if you experience asthma or breathing difficulties that are serious or if you think you may be ill.

Common side effects of zanamivir include:

  • Headache, dizziness;
  • Nausea, vomiting, diarrhea;
  • Cough, difficulty breathing, wheezing
  • Ear pain,
  • Symptoms of a cold, like congestion, sneezing, and a sore throat.

This isn't a complete list of all the side effects. Others could happen. Consult your physician for advice regarding medical adverse effects. You can report any side effects to the FDA at 1-800-FDA-1088.


Some users of the drug zanamivir have experienced sudden and unusual changes in behavior or mood, typically among children. It's not clear if zanamivir is the cause. Even without zanamivir, anyone suffering from influenza may experience neurological or behavioral symptoms that can lead to hallucinations or confusion. Contact your doctor to know if a person taking the medicine shows any signs of unusual behavior or thoughts.

Before you take this drug

It is not recommended to use zanamivir in the event that you are allergic to zanamivir or lactose (milk sugar).Use zanamivir only to treat symptoms of the flu in children under seven years old. Children, even as young as 5 years old, can take zanamivir to stop influenza symptoms.

Speak to your doctor if you have ever suffered from:

  • Asthma, chronic obstructive respiratory condition (COPD), or any other lung disease.

It isn't known if this medication will cause harm to the unborn child. But being sick during pregnancy with influenza can cause birth defects, low birth weight, premature birth, or stillbirth. Your doctor will determine if you should take zanamivir if you are expecting.

The Centres for Disease Control and Prevention (CDC) suggest that pregnant women get a flu shot every year to protect against influenza. Zanamivir is not meant to replace the annual flu shot.It is not recommended to breastfeed while taking this medication. Consult your physician about any potential risks.

How to take Zanamivir?

Follow all instructions on the prescription label and go through all medication guides or instruction sheets. Follow the medication exactly as prescribed.Take zanamivir as fast as you can after symptoms of the flu occur, like fever, chills, aches and discomfort, a sore throat, and a stuffy or runny nose.

Be sure to read and adhere to any instructions for use that come with your medication. Talk to your pharmacist or doctor for clarification if you are unsure of the instructions.Zanamivir comes in foil packets that look like discs and include four blisters of the medicine. These discs are placed in an apparatus called a diskhaler, which you take with the medicine. The device opens and releases a zanamivir blister each time you inhale using the inhaler.

To treat symptoms of the flu For flu-related symptoms, take 2 inhalations each day for 5 days. On the first day of treatment, you should space your doses by at least two hours between each dose. In the days following, you should space your doses for at least 12 hours between each dose.

To avoid symptoms of the flu Inhale two times each day for between 10 and 28 days. Follow the instructions of your physician.Use an air nebulizer or ventilator in order to administer zanamivir. Zanamivir inhalation powder shouldn't be mixed with liquid.If you plan to use a bronchodilator at the same time as zanamivir, take the bronchodilator first.

Take this medication for the entire prescribed duration, even if symptoms begin to improve. Contact your physician if your symptoms don't improve or if they become worse.Storage at room temperature, far from heat and moisture. Remove the diskhaler when your treatment is over.

What happens if I miss the dose?

Utilize the medicine as soon as you are able, but take a break from any missed doses if the next dose falls within less than two hours. Don't take two doses at once.

Call your doctor if you miss several doses.

What happens if I overdose?

For medical emergencies, seek emergency medical attention or contact the Poison Help line toll-free at 1-800-222-1222.

What should be avoided?

Avoid using the nasal flu vaccination (FluMist) within the first 48 hours following taking the drug zanamivir. Zanamivir can affect the drug actions of FluMist, which makes the vaccine less efficient. Follow the directions of your doctor.

Interaction with other drugs

Other drugs can also influence zanamivir, such as prescription and over-the-counter medicines, vitamins, and herbal products. Inform your physician about all your medications currently used as well as any medications you are about to start or stop taking.