What it is used for
- Treatment of influenza (flu)
- Prevention of influenza after exposure
- Useful when oral antivirals are unsuitable
How it works
Zanamivir blocks an enzyme (neuraminidase) the influenza virus needs to spread between cells, limiting how far the infection spreads and easing symptoms when started early. It works against influenza viruses only, not colds or other respiratory infections.
How it is taken
Most commonly used as an inhaled powder breathed in through a special device (a hospital injectable form also exists for severe cases). For treatment it works best when started within the first day or two of symptoms and can also be used preventively after close contact with flu. Use the inhaler exactly as your doctor, pharmacist, or label directs.
No doses here on purpose. The right strength and schedule depend on you — only a doctor or pharmacist should set them. Always follow your prescription and the label.
Common side effects
- Headache
- Cough or throat irritation
- Stuffy or runny nose
- Diarrhoea
- Nausea
Serious effects — get help
- Wheezing or sudden breathing difficulty, especially in people with asthma or lung disease
- Severe allergic or skin reaction
- Sudden confusion or abnormal behaviour (reported mainly in young people)
If a reaction is severe — for example trouble breathing, swelling of the face or throat, or collapse — go to the nearest emergency room now or call your local emergency number. Do not wait for an online consultation.
Interactions to watch
- Live attenuated (nasal spray) flu vaccine may be less effective if given close to zanamivir
- Few other significant interactions
- Tell your clinician about your medicines and recent vaccinations
Who should take care
- Use with caution if you have asthma or chronic lung disease, as it can trigger wheezing; keep a reliever inhaler to hand
- Do not put the powder in a nebuliser or ventilator unless specifically instructed
- Use in pregnancy or breastfeeding on clinical advice
- It does not replace the yearly flu vaccine