What is Zanamivir: Uses, Dosage, Side Effects and More

Zanamivir is an antiviral medication that helps your body fight off the flu virus. It's a prescription medicine that comes as a powder you breathe in through a special inhaler device, making it different from most flu medications that you swallow as pills.

This medication works best when you start taking it within the first 48 hours of feeling flu symptoms. Think of it as giving your immune system a helpful boost when it needs it most during those early, challenging days of illness.

What is Zanamivir?

Zanamivir belongs to a group of medicines called neuraminidase inhibitors. These drugs specifically target the flu virus and help stop it from spreading to healthy cells in your body.

Unlike other flu medications, zanamivir comes as a dry powder that you inhale directly into your lungs using a device called a Diskhaler. This delivery method allows the medicine to reach the places where flu viruses typically multiply most actively.

The medication is designed to work against both influenza A and influenza B viruses. However, it won't help with common colds or other viral infections that aren't caused by the flu virus.

What is Zanamivir Used For?

Zanamivir serves two main purposes in flu treatment and prevention. It can help treat active flu infections and also prevent flu in certain situations.

For treatment, doctors prescribe zanamivir when you already have flu symptoms like fever, body aches, and fatigue. The medicine works to reduce how long you feel sick and may lessen the severity of your symptoms.

For prevention, zanamivir might be recommended if you've been exposed to someone with the flu but haven't gotten sick yet. This is especially helpful for people at higher risk for flu complications, such as older adults or those with chronic health conditions.

How Does Zanamivir Work?

Zanamivir works by blocking a protein called neuraminidase that flu viruses need to spread throughout your body. When this protein is blocked, newly formed viruses get trapped and can't move on to infect other healthy cells.

This medication is considered moderately strong for antiviral drugs. It's not as aggressive as some other treatments, but it's specifically designed to target flu viruses effectively when used at the right time.

The medicine reaches your respiratory system directly through inhalation, which means it can start working right where flu viruses typically cause the most problems. This targeted approach can be more effective than medications that have to travel through your digestive system first.

How Should I Take Zanamivir?

You'll take zanamivir using a special inhaler device called a Diskhaler that comes with your medication. The typical dose is two inhalations twice daily, about 12 hours apart.

It's important to take zanamivir on an empty stomach or at least one hour before meals. Food doesn't necessarily interfere with the medication, but taking it without food may help you avoid any potential stomach upset.

Here's how to use your Diskhaler properly:

1. Load the disk containing the medication into the device
2. Pierce the blister by lifting and pressing the lid
3. Breathe out fully, then place your lips around the mouthpiece
4. Breathe in quickly and deeply through your mouth
5. Hold your breath for a few seconds, then breathe out slowly

Always rinse your mouth with water after each dose to prevent throat irritation. If you use other inhalers for conditions like asthma, use those first, then wait at least 15 minutes before using zanamivir.

How Long Should I Take Zanamivir For?

For treating active flu symptoms, you'll typically take zanamivir for 5 days. This course of treatment usually starts working within the first day or two, even if you don't feel dramatically better right away.

If you're taking zanamivir to prevent flu after exposure, your doctor might prescribe it for 10 days. In some cases, such as during a community flu outbreak, you might need to take it for up to 28 days.

It's crucial to complete the full course of medication, even if you start feeling better before finishing all the doses. Stopping too early could allow the virus to bounce back and make you sick again.

What Are the Side Effects of Zanamivir?

Most people tolerate zanamivir well, but like all medications, it can cause some side effects. The good news is that serious side effects are relatively uncommon.

Common side effects you might experience include:

• Throat irritation or soreness
• Cough or hoarseness
• Nasal congestion
• Headache
• Dizziness
• Nausea or stomach discomfort

These symptoms are usually mild and tend to improve as your body adjusts to the medication. Rinsing your mouth after each dose can help reduce throat irritation.

More serious but less common side effects include breathing problems or bronchospasm, especially in people with asthma or other lung conditions. If you experience sudden difficulty breathing, wheezing, or chest tightness, contact your doctor immediately.

Very rare but serious side effects include severe allergic reactions, which might cause swelling of your face, lips, tongue, or throat, along with difficulty breathing or swallowing. These reactions require immediate medical attention.

Who Should Not Take Zanamivir?

Zanamivir isn't suitable for everyone, and certain health conditions or circumstances make it inadvisable to use this medication.

You should avoid zanamivir if you have a known allergy to the medication or any of its ingredients. People with severe asthma or chronic obstructive pulmonary disease (COPD) may also need to avoid it, as the inhaled powder can sometimes trigger breathing problems.

Children under 7 years old typically shouldn't use zanamivir because they may have difficulty using the inhaler device properly. The medication requires good coordination and breathing technique to be effective.

People with severe kidney disease may need dose adjustments or alternative treatments. Your doctor will consider your kidney function when deciding if zanamivir is right for you.

If you're pregnant or breastfeeding, discuss the risks and benefits with your healthcare provider. While zanamivir appears to be relatively safe during pregnancy, your doctor will want to weigh the potential benefits against any possible risks.

Zanamivir Brand Names

Zanamivir is most commonly available under the brand name Relenza. This is the primary brand you'll likely encounter when your doctor prescribes this medication.

Relenza comes with its own Diskhaler device and rotating disks that contain the medication. Each disk has multiple doses, and you'll rotate to a new position for each inhalation.

Currently, there aren't any generic versions of zanamivir available in most countries, so Relenza remains the main option for this particular antiviral medication.

Zanamivir Alternatives

If zanamivir isn't suitable for you, several other antiviral medications can treat or prevent the flu. The choice depends on your specific situation and health needs.

Oseltamivir (Tamiflu) is probably the most well-known alternative. It comes as capsules or liquid that you take by mouth, which some people find easier than using an inhaler. Like zanamivir, it works best when started within 48 hours of symptom onset.

Peramivir (Rapivab) is another option that's given as a single intravenous infusion in a healthcare setting. This might be chosen for people who can't take oral medications or use inhalers effectively.

Baloxavir marboxil (Xofluza) is a newer antiviral that works differently from zanamivir. It's taken as a single oral dose, which some people prefer for convenience.

Your doctor will consider factors like your age, other health conditions, and how well you can use different types of medications when recommending the best antiviral for your situation.

Is Zanamivir Better Than Oseltamivir?

Both zanamivir and oseltamivir are effective antiviral medications, but they each have advantages and disadvantages that make them better suited for different people and situations.

Zanamivir may have a slight edge in terms of viral resistance. Some flu strains have developed resistance to oseltamivir, but resistance to zanamivir remains relatively rare. This means zanamivir might be more effective against certain flu viruses.

However, oseltamivir is often more convenient because it comes as pills or liquid that you swallow, rather than requiring a special inhaler. This makes it easier for children, elderly people, or anyone who has trouble with inhalers to use effectively.

Zanamivir tends to cause fewer stomach-related side effects like nausea and vomiting, which are more common with oseltamivir. But it can cause more respiratory irritation due to the inhalation method.

Your doctor will choose the medication that's most appropriate for your specific situation, considering factors like your age, other health conditions, and your ability to use the medication properly.