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Zanamivir

Why is it prescribed?

Zanamivir is an antiviral medicine for the treatment of influenza and for reducing the chance of getting the flu in community and household settings, in adults and children 7 years of age and older.  It should lessen symptoms and shorten the duration of the flu.  It is important to remember that zanamivir is not a vaccine and that it is sometimes used in people who have had their annual flu shot. 

Products that have this ingredient include •Relenza® •

See other drugs used in the treatment of •flu •influenza •

Along with its needed effects, zanamivir may cause some unwanted or undesirable effects. Generally, zanamivir is well tolerated and many people will not experience unwanted effects.
Possible unwanted effects include:

  • headache
  • diarrhea
  • nausea and vomiting
  • irritation of the nose
  • cough
  • breathing problems (e.g. bronchospasm) has occurred in patients with asthma or COPD

Zanamivir is an antiviral medication that stops the spread of the influenza virus to healthy cells in your respiratory tract.


Zanamivir is generally not recommended for treatment in people with severe lung disease due to the risk of side effects.

Drug Interactions: It is unlikely that zanamivir will interact with any other medications you are taking. However, it is important that you inform your doctor and pharmacist of all the prescription and over-the-counter medications that you are taking.

Use is not recommended in the following situations:

  • allergy to zanamivir or any component of the inhalation powder (including lactose)
  • children under 7 years of age

Caution is recommended in the following situations:

  • people with chronic respiratory disease

Use in pregnancy: Not recommended for use during pregnancy.  Be sure to inform your doctor and pharmacist if you are or suspect you may be pregnant.
Use while breastfeeding: It is not known whether zanamivir passes into the breast milk. Your doctor or pharmacist will advise you on what is best for you and your baby.