Zanamivir

Pronunciation: pronunciation varies by local usage.

Generic name
Zanamivir
Brand names
Relenza
Drug class
Neuraminidase inhibitor (antiviral)

Availability and supply rules vary by country

Trade names by country: United States · Canada

Australia: · Full directory

What Zanamivir is and how it works

Uses, formulations, monitoring, and supply rules can differ by patient, product, and country. Follow the exact local product information and professional advice.

What Zanamivir is used for

Influenza treatment (age 7+)

For uncomplicated acute illness due to influenza A and B, started within 2 days of symptom onset.

Influenza prevention/prophylaxis (age 5+)

Influenza prevention/prophylaxis (age 5+)

Before taking Zanamivir

Do not take / not appropriate for

  • Do not use zanamivir (RELENZA) if you have ever had an allergic reaction to zanamivir or to any ingredient of RELENZA, including milk proteins. The inhalation powder is delivered in lactose, which contains milk protein. (all countries)
  • Zanamivir is not recommended for treating or preventing influenza in anyone with an underlying airways disease such as asthma or chronic obstructive pulmonary disease (COPD). This is a labelled warning rather than an absolute contraindication, but serious bronchospasm, including fatal cases, has been reported, so an alternative influenza treatment is generally used in these patients. (all countries)

Tell your clinician about

  • Any allergy to milk or milk protein, or any previous reaction to an inhaled powder.
  • Asthma, COPD or any other long-term lung condition — zanamivir is not recommended in underlying airways disease.
  • If you do use zanamivir and you have a lung condition, make sure a fast-acting bronchodilator inhaler is available; if you use a scheduled bronchodilator, take it before each zanamivir dose.
  • Stop zanamivir and seek medical help straight away if you develop wheeze, tightness in the chest, breathing difficulty, swelling of the mouth or throat, or a serious rash — allergic-like reactions including oropharyngeal oedema, serious skin rashes and anaphylaxis have been reported.
  • Pregnancy, plans for pregnancy, or breastfeeding.

How to take Zanamivir

  • General Instructions: Zanamivir is inhaled using the Diskhaler device; each dose is 2 inhalations, each inhalation from 1 blister, as directed by your prescriber.. When To Seek Review: Seek immediate medical attention for wheezing, chest tightness, or difficulty breathing; let the clinician you see advise on whether to continue or stop.. Storage: Store at room temperature, away from moisture and heat.

Procedures and treatment changes

Tell the treating team before surgery, procedures, or any medicine change. Do not alter treatment without the responsible clinician.

Missed dose

If you miss a dose, contact your prescriber or pharmacist for guidance on your treatment course.

Overdose

In case of overdose, seek emergency medical attention immediately.

Side effects

Side effects and their urgency vary; report severe, persistent, or concerning symptoms.

Headache

What to notice: A common side effect.

What to do: Contact your prescriber if severe or persistent. (2)

Cough or throat/tonsil discomfort

What to notice: A common side effect.

What to do: Contact your prescriber if symptoms worsen or breathing becomes difficult (see serious warnings). (2)

Serious warnings

Serious breathing problems (bronchospasm) —

Action: Zanamivir can cause serious bronchospasm, including fatal cases, in people with and without lung disease. It is not recommended for people with asthma, COPD, or other underlying airway disease. Seek immediate medical attention for wheezing, chest tightness, or difficulty breathing; the clinician you see will decide whether to stop treatment.

Allergic reaction —

Action: Seek immediate medical attention for swelling, difficulty breathing, or severe rash.

Interactions

Medicine or testEffectAction
Live attenuated influenza vaccineMay reduce vaccine effectiveness if given close together.Discuss timing with your prescriber. (2)

Pregnancy, breastfeeding, kidney/liver function, age

Pregnancy

Requires a primary-source research pass before this section can be completed.

Breastfeeding

Requires a primary-source research pass before this section can be completed.

Children

Frequency: Treatment approved from age 7, prophylaxis from age 5, same regimen as adults.. Weight Based: Not weight-based.. Max Daily Dose: 2 inhalations (10 mg) per dose, per label schedule.. Max Single Dose: 2 inhalations (10 mg).. Age Restrictions: Not approved for treatment below age 7 or prophylaxis below age 5.

Renal_impairment

Requires a primary-source research pass before this section can be completed.

Hepatic_impairment

Requires a primary-source research pass before this section can be completed.

Monitoring

Storage

Follow the exact product label and keep medicines away from children.

Clinician-facing summary

Clinician-facing context only.

General

Indication: Influenza treatment (age 7+)

Dose summary: Treatment: 2 inhalations (10 mg) twice daily for 5 days, started within 2 days of symptom onset. Prophylaxis: 2 inhalations once daily for 10 days (household exposure) or 28 days (community outbreak), per the treating clinician.

Renal context: No specific renal dose-adjustment guidance was found in the sources reviewed for the inhaled formulation. (2)

Frequently asked questions

What is Zanamivir used for?

Zanamivir (Relenza) is used to treat influenza A and B in people 7 years and older who have had symptoms for no more than 2 days, and to help prevent influenza in people 5 years and older.

What are the side effects of Zanamivir?

Common side effects include headache and cough. Zanamivir can cause serious breathing problems (bronchospasm), including fatal cases, especially in people with asthma or other lung disease — it is not recommended for people with underlying airway disease. Seek immediate medical attention for wheezing or difficulty breathing; let the clinician you see advise on whether to continue or stop.

How should I take Zanamivir?

Zanamivir is inhaled using the Diskhaler device supplied with the medicine — each dose is 2 inhalations, each inhalation from 1 blister, exactly as your prescriber directs.

What is the generic name of Zanamivir?

The generic name is Zanamivir. It is sold under brand names including Relenza.

What class of drug is Zanamivir?

Zanamivir is classed as: Neuraminidase inhibitor (antiviral).

References

  1. Zanamivir Prescribing InformationU.S. National Library of Medicine, DailyMed · United States · accessed 2026-08-03 · source 1
  2. RELENZA (zanamivir) inhalation powder — Prescribing Information (DailyMed)DailyMed / authoritative reference · United States · accessed 2026-08-08 · source 2
  3. RELENZA (ZANAMIVIR) POWDER [A-S MEDICATION SOLUTIONS] — US prescribing information (DailyMed SPL)U.S. National Library of Medicine (DailyMed) · US · accessed 2026-08-14 · source 3
  4. Zanamivir Oral Inhalation — patient drug information (MedlinePlus)U.S. National Library of Medicine (MedlinePlus) · US · accessed 2026-08-14 · source 4
  5. RELENZA — FDA approval record (Drugs@FDA NDA021036)U.S. Food and Drug Administration · US · accessed 2026-08-14 · source 5
  6. Zanamivir — RxNorm normalized drug concept (RXCUI 69722)U.S. National Library of Medicine (RxNorm) · US · accessed 2026-08-14 · source 6

Brand names by country

Single-ingredient Zanamivir names are shown separately by country. Product availability, strengths, and supply rules can change; combination products are not included here.

Priority countries

United States

  • RELENZA5 mg · a-s medication solutions

Canada

  • RELENZA
View brands in additional countries.

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