Relenza (zanamivir)

What is Relenza?

Relenza is a brand-name prescription drug. It’s FDA-approved to:

• Treat influenza (flu) in children ages 7 years and older. For this use, flu symptoms must have occurred within the past 48 hours.
• Help prevent the flu in adults and in children ages 5 years and older.

Relenza is approved for these uses in certain situations. For more information about how the drug is used, see the “Relenza for the flu” section below.

Relenza contains the active drug zanamivir. It belongs to a group of drugs called antivirals. Relenza works by keeping the flu virus from spreading in your body.

Relenza comes as a powder you breathe in using a special inhaler provided with the drug. The powder comes in 5-mg doses, delivered in one puff of the inhaler. Relenza is typically used either once or twice per day.

Effectiveness

For information about the effectiveness of Relenza, see the “Relenza for the flu” section below.

Relenza generic

Relenza is available only as a brand-name medication. It’s not currently available in generic form.

A generic drug is an exact copy of the active drug in a brand-name medication. Generics usually cost less than brand-name drugs.

Relenza contains the active drug zanamivir.

Relenza vs. Tamiflu

You may wonder how Relenza compares with other medications that are prescribed for similar uses. Here we look at how Relenza and Tamiflu are alike and different.

Ingredients

Relenza contains the active drug zanamivir. Tamiflu contains the active drug oseltamivir. Both medications belong to a group of drugs called antivirals.

Uses

Both Relenza and Tamiflu are FDA-approved for the following uses:

* Flu symptoms must have occurred within the past 48 hours.

Drug forms and administration

Relenza comes as a powder you breathe in using a type of inhaler called a Diskhaler. Relenza is typically taken as two puffs from the Diskhaler once or twice per day.

Tamiflu comes as capsules or a liquid that you swallow. It’s typically taken once or twice per day.

Side effects and risks

Relenza and Tamiflu both contain drugs used to help prevent or treat the flu. Therefore, these medications can cause very similar side effects, but some different ones as well. Below are examples of these side effects.

Mild side effects

These lists contain up to 10 of the most common mild side effects that can occur with each drug, as well as mild side effects that both drugs may share.

• Can occur with Relenza:
  • bronchitis (inflamed or irritated airway)
  • cough
  • ear, nose, or throat infection
  • sinusitis (inflamed or irritated sinuses)
  • dizziness
  • fever or chills
  • joint problems, such as joint pain and arthritis
• Can occur with Tamiflu:
  • general body pain
• Can occur with both Relenza and Tamiflu:
  • diarrhea
  • nausea and vomiting
  • headache

Serious side effects

These lists contain examples of serious side effects that can occur with Relenza or Tamiflu, as well as serious side effects that both drugs may share.

• Can occur with Relenza:
  • bronchospasm (tightening of the muscles in the airway)
• Can occur with Tamiflu:
  • skin reactions, such as Stevens-Johnson Syndrome, toxic epidermal necrolysis, and erythema multiforme
• Can occur with both Relenza and Tamiflu:
  • allergic reaction
  • problems with the mind or nervous system, such as unusual behavior, delirium, or hallucinations (seeing or hearing things that aren’t there)

Effectiveness

Relenza and Tamiflu haven’t been directly compared in clinical studies. However, separate studies of the two drugs were compared in a larger review of studies. This review found both Relenza and Tamiflu to be effective for helping prevent or treat the flu.

Costs

Relenza and Tamiflu are both brand-name drugs. There are currently no generic forms of Relenza. However, Tamiflu is available as a generic medication called oseltamivir. Brand-name medications usually cost more than generics.

Relenza costs significantly less than brand-name Tamiflu but significantly more than generic Tamiflu. The actual price you’ll pay for either drug depends on your insurance plan, your location, and the pharmacy you use.

Relenza side effects

Relenza can cause mild or serious side effects. The following lists contain some of the key side effects that may occur while using Relenza. These lists do not include all possible side effects.

For more information about the possible side effects of Relenza, talk with your doctor or pharmacist. They can give you tips on how to deal with any side effects that may be bothersome.

Note: The Food and Drug Administration (FDA) tracks the side effects of drugs it has approved. If you would like to notify the FDA about a side effect you’ve had with Relenza, you can do so through MedWatch.

Mild side effects

Mild side effects* of Relenza can include:

• bronchitis (inflamed or irritated airway)
• cough
• diarrhea
• ear, nose, or throat infection
• headache
• nausea and vomiting
• sinusitis† (inflamed or irritated sinuses)
• dizziness†
• fever or chills†
• joint problems,† such as joint pain and arthritis

Most of these side effects may go away within a few days or a couple of weeks. But if they become more severe or don’t go away, talk with your doctor or pharmacist.

* This is a partial list of mild side effects from Relenza. To learn about other mild side effects, talk with your doctor or pharmacist, or view Relenza’s prescribing information.
† For more information on this side effect, see “Side effect details” below.

Serious side effects

Serious side effects from Relenza aren’t common, but they can occur. Call your doctor right away if you have serious side effects. Call 911 or your local emergency number if your symptoms feel life threatening or if you think you’re having a medical emergency.

Serious side effects and their symptoms can include:

• Problems with the mind or nervous system.* Symptoms can include:
  • delirium
  • hallucinations (seeing or hearing things that aren’t there)
  • seizures
  • unusual behavior
• Allergic reaction.†
• Bronchospasm (tightening of the muscles in the airway).†

* Clinical studies did not identify this side effect, but it was reported after Relenza was made available to the public. It’s not clear whether Relenza or the flu itself caused this side effect. For more details, see the drug’s prescribing information.
† For more information about this side effect, see “Side effect details” below.

Side effects in children

Relenza is approved to treat influenza (flu) in children ages 7 years and older who’ve had flu symptoms for no more than 48 hours. It’s also approved to help prevent the flu in children ages 5 years and older.

The side effects of Relenza in children are similar to the side effects in adults. However, children who have the flu may be more likely to experience problems with the mind or nervous system. But it isn’t known how often these problems may have happened in clinical studies of children using Relenza. It’s also not known whether Relenza or the flu itself caused these side effects.

For more information, see the “Mild side effects” and “Serious side effects” sections above.

Side effect details

You may wonder how often certain side effects occur with this drug. Here’s some detail on specific side effects this drug may cause.

Allergic reaction

As with most drugs, some people can have an allergic reaction while using Relenza. However, it isn’t known how often this may have happened in clinical studies of the drug.

Symptoms of a mild allergic reaction can include:

• skin rash
• itchiness
• flushing (warmth, swelling, or redness in your skin)

A more severe allergic reaction is rare but possible. Symptoms of a severe allergic reaction can include:

• swelling under your skin, typically in your eyelids, lips, hands, or feet
• swelling of your tongue, mouth, or throat
• trouble breathing

Call your doctor right away if you have an allergic reaction to Relenza, as the reaction could become severe. Call 911 or your local emergency number if your symptoms feel life threatening or if you think you’re having a medical emergency.

Sinusitis

Sinusitis (inflamed or irritated sinuses) can occur while using Relenza.

Clinical studies compared Relenza with a placebo (a treatment with no active drug) for treating influenza (flu) in adults and in children ages 12 and older. In these studies:

• 2% to 3% of people who used Relenza had sinusitis (the percentage varied depending on how long the drug was used)
• 2% of people who used a placebo had sinusitis

It isn’t known how many adults or children may have had sinusitis while using Relenza or a placebo to help prevent the flu.

Symptoms of sinusitis may include congestion, cough, a runny or stuffy nose, or pressure or pain in the face.

If you have bothersome sinusitis while using Relenza, talk with your doctor. They can suggest ways to help treat the symptoms.

Dizziness

Some people may have dizziness while using Relenza.

Clinical studies looked at adults and children ages 12 and older. In these studies:

• 1% to 2% of people had dizziness while using Relenza to treat the flu (the percentage varied depending on how long the drug was used)
• less than 1% of people had dizziness while using a placebo to treat the flu

The percentage of children younger than 12 years who may have had dizziness while using Relenza or a placebo (a treatment with no active drug) to treat the flu isn’t known. And the percentage of adults or children who may have had dizziness while using these treatments to help prevent the flu wasn’t reported.

Talk with your doctor if you’re concerned about having dizziness while using Relenza.

Fever or chills

Some people may have fever or chills while they use Relenza.

Clinical studies of adults and children ages 5 years and older compared Relenza with a placebo (a treatment with no active drug) to help prevent the flu. Of these, fever or chills happened in:

• 5% to 9% of people who used Relenza (the percentage varied depending on how long the drug was used)
• 4% to 10% of people who used a placebo (the percentage varied depending on how long the placebo was used)

It isn’t known how many adults or children may have had fever or chills while using Relenza or a placebo to treat the flu.

If you have bothersome fever or chills while using Relenza, talk with your doctor.

Joint problems

Joint problems, such as joint pain and arthritis, are possible side effects of Relenza. Symptoms of these conditions may also include swelling or stiffness of the joints.

Clinical studies involved adults and children ages 5 years and older. They used either Relenza or a placebo (a treatment with no active drug) for 28 days to prevent the flu. In these studies:

• 2% of people who used Relenza had joint pain or arthritis
• less than 1% of people who used a placebo had joint problems or arthritis

It’s not known how many adults or children may have had joint pain or arthritis while using Relenza or a placebo to treat the flu.

If you have joint pain or arthritis while using Relenza, talk with your doctor about ways to relieve your symptoms.

Bronchospasm

Some people may experience bronchospasm (tightening of the muscles in the airway) while using Relenza.

It isn’t known how often this side effect may have happened in clinical studies that looked at Relenza for preventing or treating the flu.

Symptoms of bronchospasm can include pain or tightness in the chest and back, trouble breathing, or wheezing.

Bronchospasm can be a life threatening medical emergency. If you have any symptoms of bronchospasm while using Relenza, call 911 or your local emergency number right away.

The risk of bronchospasm while using Relenza may be higher in people who have asthma or chronic obstructive pulmonary disease (COPD). Be sure to tell your doctor if you have asthma or COPD before you start taking Relenza. They may recommend a treatment for you other than Relenza.

Relenza cost

As with all medications, the cost of Relenza can vary. The actual price you’ll pay depends on your insurance plan, your location, and the pharmacy you use.

Before approving coverage for Relenza, your insurance company may require you to get prior authorization. This means that your doctor and insurance company will need to communicate about your prescription before the insurance company will cover the drug. The insurance company will review the prior authorization request and decide if the drug will be covered.

If you’re unsure if you’ll need to get prior authorization for Relenza, contact your insurance company.

Financial and insurance assistance

If you need financial support to pay for Relenza, help is available. NeedyMeds lists programs that may help lower the cost of Relenza. For more information and to find out if you’re eligible for support, visit the NeedyMeds website.

Generic version

Relenza isn’t available in a generic form. A generic drug is an exact copy of the active drug in a brand-name medication. Generics tend to cost less than brand-name drugs.

Relenza dosage

The Relenza dosage your doctor prescribes will depend on whether you’re using Relenza to help prevent or treat influenza (flu).

The following information describes dosages that are commonly used or recommended. However, be sure to take the dosage your doctor prescribes for you. Your doctor will determine the best dosage to fit your needs.

Drug forms and strengths

Relenza comes as a powder you breathe in using an inhaler provided with the drug. This inhaler is called a Diskhaler. The powder comes in disk-shaped blister packs designed to fit in the inhaler. The blister pack is called a Rotadisk. Each blister in the Rotadisk contains 5 milligrams (mg) of the active drug zanamivir.

Dosage for treating the flu

The only approved dose of Relenza for treating the flu is 10 mg. The dose is taken as two puffs (one 5-mg blister per puff) from the Diskhaler twice per day for 5 days.

For this purpose, you should start taking Relenza within 48 hours of when flu symptoms began.

Dosage for preventing the flu

The only approved dose of Relenza to help prevent the flu is 10 mg. The dose is taken as two puffs (one 5-mg blister per puff) from the Diskhaler once per day.

The length of time you use Relenza to help prevent the flu will depend on a couple of factors. Your doctor may prescribe Relenza if you have close contact with a person who has the flu, such as someone living in your home. To help prevent the flu in this situation, you’ll likely use Relenza for 10 days.

Your doctor might also prescribe Relenza if there are a high number of flu cases in your community. To help prevent the flu in this situation, you’ll likely use Relenza for 28 days.

Children’s dosage

The dosage for children depends on whether they’re using Relenza to treat or to prevent the flu.

Children’s dosage for treating the flu

Relenza is approved to treat the flu in children ages 7 years and older. The dose of Relenza used for children is the same as the adult dose. See the “Dosage for treating the flu” section above for more information.

Children’s dosage for preventing the flu

Relenza is also approved to help prevent the flu in children ages 5 years and older. The dose of Relenza used for children is the same as the adult dose. See the “Dosage for preventing the flu” section above for more information.

Dosage questions

Below are answers to some questions you may have about using Relenza.

What if I miss a dose?

If you miss a dose of Relenza, take the missed dose as soon as you remember. However, if it’s 2 hours or less until your next scheduled dose, just skip your missed dose. You can start using Relenza again at your normal time.

You shouldn’t take two doses at once to make up for a missed dose. This can raise your risk for side effects from Relenza. (For more information, see the “Relenza side effects” section above.)

To help make sure that you don’t miss a dose, try using a medication reminder. This can include setting an alarm on your phone or downloading a reminder app. A kitchen timer can work, too.

Will I need to use this drug long term?

Relenza isn’t meant to be used as a long-term treatment. Relenza is used as a short-term treatment to help prevent or treat the flu. It’s typically taken for 5 or 10 days. However, you can use it for up to 28 days to help prevent the flu if your community has a high number of flu cases.

Talk with your doctor if you have questions about how long you should take this drug. They’ll recommend the length of treatment that’s right for you.

Relenza for the flu

The Food and Drug Administration (FDA) approves prescription drugs such as Relenza to treat certain conditions. Relenza may also be used off-label for other conditions. Off-label use is when a drug that’s approved to treat one condition is used to treat a different condition.

Relenza is FDA-approved to help prevent and treat influenza (flu). These uses, along with certain limitations, are described in more detail below.

What is the flu?

The flu is a sickness caused by the influenza virus. The virus is spread easily through coughing, sneezing, or talking. After you’ve contracted the virus, it can take a couple of days to start having symptoms.

Symptoms of the flu may include:

• body aches or muscle aches
• cough
• fatigue (lack of energy)
• fever or chills
• headache
• runny or stuffy nose
• sore throat
• vomiting
• diarrhea

Relenza for treating the flu

Relenza is FDA-approved to treat the flu in adults and in children ages 7 years and older. Specifically, Relenza is approved to treat the flu caused by the influenza A or influenza B virus. For this purpose, a person must have had flu symptoms for no more than 48 hours.

Limitations for this use

Relenza isn’t approved to treat the flu in people who have certain lung conditions, such as asthma or chronic obstructive pulmonary disease (COPD). This is because Relenza increases the risk of bronchospasm* (tightening of the muscles in the airway). As well, Relenza hasn’t been found to be effective for treating flu in people with these conditions.

* For more information about bronchospasm, see “Bronchospasm” in the “Relenza side effects” section above.

Effectiveness for treating the flu

Relenza has been found effective for treating the flu.

Clinical studies compared Relenza to a placebo (a treatment with no active drug) for treating the flu. The studies included adults and children ages 12 years and older who had flu symptoms for no more than 48 hours.

Researchers looked at the time it took for people’s flu symptoms to ease or stop entirely after each treatment. Flu symptoms evaluated include cough, headache, muscle aches, and sore throat.

In people who used Relenza, at least half saw their symptoms improve 1 day to 1.5 days faster than those who used a placebo. The exact length of time that symptoms lasted for people in these studies isn’t known, however.

Relenza for preventing the flu

Relenza is also FDA-approved to help prevent the flu in adults and in children ages 5 years and older. Relenza can help keep people who’ve been exposed to the influenza virus from getting sick.

Limitations for this use

Relenza isn’t approved to help prevent the flu in people who have certain lung conditions, such as asthma or chronic obstructive pulmonary disease (COPD). This is because Relenza increases the risk of bronchospasm* (tightening of the muscles in the airway). This side effect could be dangerous for someone with certain breathing problems.

Relenza also hasn’t been found effective for preventing the flu in people who live in nursing homes.

For preventing the flu, Relenza shouldn’t replace an annual flu vaccination.† The Centers for Disease Control and Prevention (CDC) recommends the flu vaccine as the most effective way to prevent the flu. The CDC encourages every person age 6 months and older to get a flu vaccine each year.

If you have questions about whether the flu vaccine is right for you, talk with your doctor.

* For more information about bronchospasm, see “Bronchospasm” in the “Relenza side effects” section above.
† Relenza can interact with certain forms of flu vaccine. For more information, see “Relenza and flu vaccines” in the “Relenza interactions” section below.

Effectiveness for preventing the flu

Relenza has been found to be effective for helping prevent the flu.

Clinical studies looked at whether Relenza prevented people from getting the flu from someone living in their home. Studies have also looked at whether Relenza prevented people from getting the flu in communities that had a flu outbreak.

These studies included adults and children ages 5 years and older. Researchers compared how many people got the flu while using either Relenza or a placebo (a treatment with no active drug).

In homes where at least one person had the flu:

• 4.1% of homes had at least one new case of the flu while using Relenza
• 19% of homes had at least one new case of the flu while using a placebo

In communities that had a flu outbreak:

• 0.2% to 2% of people got the flu while using Relenza
• 1.4% to 6.1% of people got the flu while using a placebo

Relenza and children

Relenza is approved to treat the flu in children ages 7 years and older who’ve had symptoms for no more than 48 hours.

One clinical study compared Relenza to a placebo for treating flu in children ages 5 to 12 years. The study included children who had flu symptoms for no more than 36 hours. Researchers looked at the length of time it took for the children’s flu symptoms to lessen or stop entirely during treatment. Flu symptoms evaluated include fever, chills, cough, headache, joint pain, muscle aches, and sore throat.

In children who used Relenza, at least half saw their symptoms improve 1 day faster than children who used a placebo. The exact length of time that symptoms lasted for children in these studies isn’t known.

Relenza is also approved to help prevent the flu in children ages 5 years and older. For more information about Relenza’s effectiveness for this use, see the “Effectiveness for preventing the flu” section above.

Relenza use with other drugs

Relenza helps prevent or treat influenza (flu) by keeping the virus from spreading in your body.

However, if you have the flu, you may still have symptoms when you first start using Relenza. These symptoms include chest congestion and cough, body and muscle aches, fever, and stuffy nose.

You can take certain over-the-counter (OTC) medications with Relenza to help lessen these symptoms. Examples of OTC drugs that can lessen chest congestion and coughing include:

• dextromethorphan (Robitussin)
• guaifenesin (Mucinex)

Examples of OTC drugs that can lessen body aches, muscle aches, and fever include:

• naproxen (Aleve)
• ibuprofen (Motrin)
• acetaminophen (Tylenol)

Examples of OTC drugs that reduce stuffy nose include:

• oxymetazoline (Afrin)
• phenylephrine (Sudafed PE)
• pseudoephedrine (Sudafed D)

Use with bronchodilators

If you have asthma or chronic obstructive pulmonary disease (COPD), you likely use bronchodilators (medications that open the airway). An example of a bronchodilator is albuterol (Ventolin HFA).

People with lung conditions generally shouldn’t use Relenza because the drug can cause bronchospasms* (tightening of the muscles in the airway). But if you do use a bronchodilator for a lung condition and your doctor advises you to take Relenza, the order you take these drugs can be important.

If you’re scheduled to take your bronchodilator dose at the same time as your Relenza dose, be sure to take your bronchodilator dose first. Using your bronchodilator before using Relenza can help lessen bronchospasms.

If you have questions about which medications you can take with Relenza, talk with your doctor or pharmacist.

* For more information about bronchospasm, see “Bronchospasm” in the “Relenza side effects” section above.

Alternatives to Relenza

Other drugs are available that can help prevent or treat influenza (flu). Some may be a better fit for you than others. If you’re interested in finding an alternative to Relenza, talk with your doctor. They can tell you about other medications that may work well for you.

Alternatives for treating the flu

Examples of other drugs that may be used to treat the flu include:

• baloxavir marboxil (Xofluza)
• oseltamivir (Tamiflu)
• peramivir (Rapivab)

Alternatives for preventing the flu

Examples of other drugs that may be used to help prevent the flu include:

• flu vaccine*†
• baloxavir marboxil (Xofluza)
• oseltamivir (Tamiflu)

* The Centers for Disease Control and Prevention (CDC) recommends the flu vaccine as the most effective way to prevent the flu. The CDC encourages every person age 6 months and older to get a flu shot each year. If you have questions about whether the flu vaccine is right for you, talk with your doctor.
† Relenza can interact with certain forms of flu vaccine. For more information, see “Relenza and flu vaccines” in the “Relenza interactions” section below.

How Relenza works

Relenza is approved to help prevent or treat influenza (flu) in adults and in in children.

The flu is a sickness caused by the influenza virus. The virus is spread easily through coughing, sneezing, or talking. After you’ve contracted the virus, it can take a couple of days before you start having symptoms. Symptoms of the flu may include body aches, muscle aches, fatigue (lack of energy), fever, or chills.

Relenza contains the active drug zanamivir, which belongs to a group of drugs called antivirals. Relenza works by blocking an enzyme (protein) called neuraminidase. The neuraminidase enzyme is responsible for releasing particles of the flu virus into your blood. By blocking this enzyme, Relenza helps prevent the flu virus from spreading in your body.

How long does it take to work?

Relenza starts working right away to help prevent or treat the flu. If you’re having symptoms of the flu, your symptoms should start easing within a couple of days.

How to use Relenza

You should take Relenza according to your doctor’s or healthcare provider’s instructions.

Relenza comes as a powder you breathe in using an inhaler provided with the drug. This inhaler is called a Diskhaler. The powder comes in disk-shaped blister packs (called Rotadisks) designed to fit in the inhaler. You’ll take two puffs of Relenza from the inhaler typically once or twice per day.

For step-by-step instructions on how to use Relenza, view Relenza’s prescribing information.

When to take

You’ll likely use Relenza once or twice per day. Try to take your doses around the same time each day. This helps to maintain a consistent amount of the drug in your body.

To help make sure that you don’t miss a dose, try using a medication reminder. This can include setting an alarm on your phone or downloading a reminder app. A kitchen timer can work, too.

Common questions about Relenza

Here are answers to some frequently asked questions about Relenza.

Is Relenza available over the counter?

No, Relenza isn’t available over the counter. You’ll need a prescription from your doctor to get Relenza.

If you have questions about whether you need to use Relenza to help prevent or treat the flu, talk with your doctor.

Will I still be contagious if I’m using Relenza for the flu?

Yes, it’s possible. If you have the flu, you’re most likely to be contagious (able to transmit the virus to other people) for the first 3 to 4 days after you get it. You may be contagious before you even know you have it. And clinical studies haven’t found Relenza effective for lowering the risk of transmitting the flu virus to other people.

If you have questions about transmitting the flu virus to others while using Relenza, talk with your doctor.

Can I get a flu vaccine while using Relenza?

Yes, if your doctor says it’s safe to do so, you can get certain types of flu vaccines while using Relenza.

The injectable flu vaccine (flu shot) contains an inactive (dead) version of the flu virus. You may be able to receive this version of the flu vaccine while using Relenza.

However, the intranasal flu vaccine (nasal spray) contains a live version of the flu virus. This can cause an interaction with Relenza unless you take certain precautions. For more information, see “Relenza and flu vaccines” in the “Relenza interactions” section below.

For helping prevent the flu, it’s important to remember that Relenza shouldn’t replace an annual flu vaccination. The Centers for Disease Control and Prevention (CDC) recommends the flu vaccine as the most effective way to prevent the flu. The CDC encourages every person age 6 months and older to get a flu vaccine each year.

If you have questions about getting a flu vaccine while using Relenza, talk with your doctor.

Will Relenza make me act differently?

Possibly. Relenza may cause problems with the mind or nervous system, such as delirium, hallucinations (seeing or hearing things that aren’t there), seizures, or unusual behavior.

This side effect is more likely to occur in children than in adults. However, it isn’t known how often this side effect may have happened in adults or children using Relenza in clinical studies. It’s also not known whether Relenza or the flu itself caused these side effects.

Be sure to tell your doctor if you experience any issues with your mind or nervous system while using Relenza.

Can I take Relenza more than 48 hours after my first flu symptoms appear?

No. In most cases, you shouldn’t start using Relenza more than 48 hours after your first flu symptoms appear.

However, be sure to take all of the Relenza doses that your doctor prescribes. You should take all doses even after your flu symptoms start to go away. Taking all of your doses will help ensure your body is rid of all of the flu virus.

If you have questions about when it’s best to take Relenza, talk with your doctor.

Is Relenza an antiviral?

Yes, Relenza is an antiviral. Relenza works by blocking an enzyme (protein) called neuraminidase. The neuraminidase enzyme is responsible for releasing particles of the flu virus into your blood. By blocking this enzyme, Relenza helps prevent the flu virus from spreading in your body.

Relenza and alcohol

There aren’t any known interactions between Relenza and alcohol.

However, drinking alcohol while you have the flu can worsen certain flu symptoms, such as headache or nausea. Drinking alcohol can also weaken your immune system, making it less effective at fighting off the flu. Therefore, if you’re using Relenza to help prevent or treat the flu, you may need to avoid drinking alcohol.

If you drink alcohol, talk with your doctor about how much is safe for you to drink while using Relenza.

Relenza interactions

Relenza isn’t known to interact with supplements, foods, or other medications. However, it may interact with certain flu vaccines.

Different interactions can cause different effects. For instance, some interactions can interfere with how well a drug works. Other interactions can increase side effects or make them more severe.

Before using Relenza, you should talk with your doctor and pharmacist. Tell them about all prescription, over-the-counter, and other drugs you take. Also, tell them about any vitamins, herbs, and supplements you use. Sharing this information can help you avoid potential interactions.

If you have questions about drug interactions that may affect you, ask your doctor or pharmacist.

Relenza and flu vaccines

Relenza can make certain types of flu vaccines less effective.

The injectable flu vaccine (flu shot) contains an inactive (dead) version of the flu virus. You may be able to receive this version of the flu vaccine while using Relenza.

However, the intranasal flu vaccine (nasal spray) contains a live version of the flu virus. If you’ve had the intranasal flu vaccine in the last 2 weeks, you shouldn’t take Relenza. This is because Relenza might make the vaccine less effective. You should also wait at least 48 hours after your last dose of Relenza before getting the nasal spray version of the flu vaccine.

For helping prevent the flu, Relenza shouldn’t replace an annual flu vaccination. The Centers for Disease Control and Prevention (CDC) recommends the flu vaccine as the most effective way to prevent the flu. The CDC encourages every person age 6 months and older to get a flu vaccine each year.

If you have questions about getting a flu vaccine while using Relenza, talk with your doctor.

Relenza and pregnancy

It’s not known if Relenza is safe to take during pregnancy. Not enough studies have been done in females who are pregnant to indicate whether Relenza will harm a fetus.

Animal studies generally didn’t find harmful side effects in the offspring of females receiving the drug. However, animal studies don’t always predict what will happen in humans.

If you’re pregnant or planning a pregnancy, talk with your doctor about the risks and benefits of using Relenza while pregnant.

Relenza and birth control

It’s not known if Relenza is safe to take during pregnancy. If you’re sexually active and you or your partner can become pregnant, talk with your doctor about your birth control needs while you’re using Relenza.

For more information about using Relenza during pregnancy, see the “Relenza and pregnancy” section above.

Relenza and breastfeeding

It’s not known whether Relenza can pass into breast milk in humans during breastfeeding.

In animal studies, the drug was present in the breast milk of lactating animals, but it didn’t cause harmful effects in offspring. However, animal studies don’t always predict what will happen in humans.

If you’re breastfeeding or planning to breastfeed while using Relenza, talk with your doctor about the risks and benefits of using Relenza.

Relenza precautions

Before using Relenza, talk with your doctor about your health history. Relenza may not be right for you if you have certain medical conditions or other factors affecting your health. These include:

• Certain lung conditions. If you have certain lung conditions, such as asthma or chronic obstructive pulmonary disease (COPD), you likely experience bronchospasm. Bronchospasm is also a possible side effect of Relenza. (For more information, see the “Relenza side effects” section above.) Therefore, using Relenza when you have asthma or COPD can increase your risk for this side effect even more. Before using Relenza, tell your doctor if you have a lung condition. They may want to monitor you more closely while you take this drug.
• Conditions that increase your risk for flu complications. Certain conditions,* such as diabetes or heart disease, can raise the risk of complications from the flu. Clinical studies haven’t shown the effectiveness of Relenza for people who have these conditions. Be sure to tell your doctor about any health conditions you have before you start using Relenza. They may recommend a different option for helping prevent or treat the flu.
• Allergic reaction. If you’ve had an allergic reaction to Relenza or any of its ingredients, you shouldn’t take Relenza. Ask your doctor which other medications are better options for you.
• Pregnancy. It’s not known if Relenza is safe to take during pregnancy. For more information, see the “Relenza and pregnancy” section above.
• Breastfeeding. It’s not known whether Relenza can pass into breast milk. For more information, see the “Relenza and breastfeeding” section above.

Note: For more information about the potential negative effects of Relenza, see the “Relenza side effects” section above.

* For a full list of these conditions, see the Centers for Disease Control and Prevention (CDC) website.

Relenza overdose

Do not use more Relenza than your doctor recommends. For some drugs, doing so may lead to unwanted side effects or overdose. (For more information on side effects, see the “Relenza side effects” section above.)

What to do in case you take too much Relenza

If you think you’ve taken too much of this drug, call your doctor. You can also call the American Association of Poison Control Centers at 800-222-1222 or use their online tool. But if your symptoms are severe, call 911 or your local emergency number, or go to the nearest emergency room right away.