Relenza (Zanamivir)
Complete patient guide for uses, dosage, side effects, and safety information
Prescription RequiredQuick Facts
What Is Relenza Used For?
Relenza is an antiviral medication that specifically targets influenza, a viral infection that affects your respiratory system. It’s designed to be inhaled directly into your lungs where the flu virus typically takes hold.
Primary Uses
Relenza treats active influenza infections and can prevent flu in special circumstances when prophylaxis is justified (such as when no suitable vaccine is available or during a pandemic). It is not recommended for routine flu prevention and does not work for common colds or other viral infections.
How It Works
Using a DISKHALER device, Relenza delivers medication directly to your lungs where flu infections start. It works by destroying a chemical on the surface of the influenza virus, which stops the virus from multiplying and spreading throughout your nose, lungs, and air passages. For best results, start taking Relenza as soon as possible after flu symptoms develop.
Good to know: Vaccination remains the primary method of preventing and controlling influenza, but Relenza provides an important treatment option when you do get sick.
How to Take Relenza
Relenza comes as a fine powder in small blisters on a circular foil disk. You’ll use a special DISKHALER device to breathe the medication directly into your lungs through your mouth.
Dosage Instructions
For treating influenza: Breathe in the contents of two blisters, twice a day (usually morning and evening), for five days. Start as soon as possible but no later than 48 hours after symptoms begin. For preventing influenza: Breathe in the contents of two blisters once a day only. Start as soon as possible after an outbreak is declared or after contact with someone who has flu. Sit in a relaxed position and don’t hold your breath longer than comfortable after inhaling. If you use other inhaled medications like asthma inhalers, use them before taking Relenza.
What If You Miss a Dose?
Take the missed dose as soon as you remember, then return to your normal schedule. If it’s almost time for your next dose, skip the missed dose and take your next dose at the regular time. Don’t miss any doses if possible, and don’t stop taking Relenza without checking with your doctor first.
Important: Never take a double dose to make up for a missed dose. Follow the instruction sheet in your DISKHALER box carefully.
Available Tablet Strengths
Side Effects
Like all medications, this medicine can cause side effects. Most are mild and temporary, but some require medical attention.
Common Side Effects
These side effects occur relatively frequently and usually don’t require emergency care:
- Feeling lightheaded
- Fainting
Seek immediate medical attention if you experience:
- Allergic reactions (wheezing, swelling of lips/mouth/face, difficulty breathing)
- Shortness of breath
- Wheezing
- Skin rash which may blister
- Widespread rash with blisters and peeling skin
- Extensive peeling of skin on much of the body surface
- Hay fever
- Lumpy rash (hives)
- Collapse
Important Warnings
Before using Relenza, it’s crucial to discuss your medical history with your doctor, especially if you have breathing problems or take other medications.
Who Should Not Take Relenza
Don’t use Relenza if you’re allergic to zanamivir or any ingredients listed on the package, or if you have severe intolerance to lactose, other sugars, or milk protein. Always check the ingredients to ensure you can safely use this medication.
Medical Conditions to Discuss
Tell your doctor if you have asthma or other breathing problems, or if you normally use an asthma inhaler. There’s a risk Relenza could cause increased breathing difficulty, especially with asthma. If you have breathing problems, keep a fast-acting bronchodilator available and use it before taking Relenza if needed. Stop taking Relenza and contact your doctor if breathing problems worsen.
Pregnancy and Breastfeeding
Don’t take Relenza if you are breastfeeding, pregnant, or trying to become pregnant, unless your doctor specifically says you should.
Children and Unusual Behavior: People with influenza, particularly children and adolescents, may be at increased risk of seizures, confusion, or abnormal behavior early in their illness. Call your doctor immediately if you notice any signs of unusual behavior.
Drug Interactions
Tell your doctor or pharmacist about all medicines you’re taking, including over-the-counter medications, vitamins, and supplements.
- Relenza is unlikely to be affected by other drugs taken for influenza (such as paracetamol or cough medicine)
- Other inhaled medications should be taken before Relenza
- Check with your healthcare provider if you’re unsure about any medications you’re taking
Alcohol & Driving
Be cautious about activities requiring alertness until you know how Relenza affects you.
Alcohol
No specific alcohol interactions are mentioned in the prescribing information, but consult your doctor about alcohol use while taking Relenza.
Driving and Operating Machinery
Be careful before you drive or use any machines or tools until you know how Relenza affects you. Since the medication can cause lightheadedness or fainting, it’s important to assess your response before engaging in these activities.
Storage
Store Relenza below 30°C in its original packaging. Keep it in a cool, dry place away from moisture, heat, or sunlight. Don’t store it in the bathroom, near a sink, in the car, or on window sills. Keep it where young children cannot reach it. Take any unwanted or expired medicine to a pharmacy for safe disposal.
Overdose Information
If you think you’ve used too much Relenza, seek urgent medical attention immediately. Phone the Poisons Information Centre (13 11 26), contact your doctor, or go to the Emergency Department at your nearest hospital, even if you don’t feel unwell or show signs of poisoning.
Frequently Asked Questions
For best results, start taking Relenza as soon as possible after developing flu symptoms, but no later than 48 hours after symptoms begin. The medication works by stopping the virus from multiplying and spreading.
No, Relenza does not work for the common cold or virus infections other than influenza. It’s specifically designed to treat and prevent influenza only.
If you have asthma, keep a fast-acting bronchodilator available and use it before taking Relenza. Stop taking Relenza and contact your doctor if your breathing problems get worse while using this medication.
Place the disk in the DISKHALER device and breathe the powder in through your mouth following the instruction sheet in the box. Sit in a relaxed position and don’t hold your breath longer than comfortable after inhaling the dose.
There’s no information on use in children under 5 years. The same dose is recommended for children 5-12 years as adults, but an adult should supervise use of the delivery device. Watch for unusual behavior and contact your doctor if it occurs.
To avoid feeling lightheaded or fainting, sit in a relaxed position and don’t hold your breath longer than comfortable after inhaling. Have someone with you while taking your dose, especially if you’re feeling unwell.
Don’t take Relenza if you are pregnant, breastfeeding, or trying to become pregnant, unless your doctor specifically says you should.
Important Disclaimer
This information is intended for general educational purposes only and should not be considered medical advice. Always consult your healthcare provider or pharmacist before starting, stopping, or changing any medication.
If you think you may have a medical emergency, call your doctor or emergency services immediately.