Medically reviewed on Oct 31, 2018
Commonly used brand name(s)
In the U.S.
Available Dosage Forms:
Therapeutic Class: Antiviral
Pharmacologic Class: Neuraminidase Inhibitor, Influenza A&B Virus
Uses For zanamivir
Zanamivir belongs to the family of medicines called antivirals, which are used to treat infections caused by viruses. Zanamivir is used in the treatment of the infection caused by the flu virus (influenza A and influenza B). Zanamivir may also be used to prevent and treat swine influenza A.
Zanamivir may reduce flu symptoms (weakness, headache, fever, cough, runny or stuffy nose, and sore throat) by 1 to 1.5 days. Zanamivir may also be used to prevent influenza infection if you have come into close contact with someone who has the flu.
Zanamivir must be started within 2 days of having flu symptoms. Zanamivir will not keep you from spreading the flu virus to other people. It may not work for everybody. Zanamivir may not be for you if you are severely sick or have a breathing problem (e.g., asthma or chronic obstructive pulmonary disease). If you receive the flu vaccine every year, continue to do so. Zanamivir is not a substitute for your yearly flu shot.
Zanamivir is available only with your doctor's prescription.
Before Using zanamivir
In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For zanamivir, the following should be considered:
Tell your doctor if you have ever had any unusual or allergic reaction to zanamivir or any other medicines. Also tell your health care professional if you have any other types of allergies, such as to foods, dyes, preservatives, or animals. For non-prescription products, read the label or package ingredients carefully.
Appropriate studies have not been performed on the relationship of age to the effects of zanamivir for the treatment of influenza in children younger than 7 years of age and for the prevention of influenza in children younger than 5 years of age. Safety and efficacy have not been established in these age groups.
Note: Zanamivir is available in Canada. It is not recommended in children younger than 12 years of age.
Appropriate studies performed to date have not demonstrated geriatric-specific problems that would limit the usefulness of zanamivir in the elderly. However, elderly patients may be more sensitive to the effects of zanamivir than younger adults, which may require caution in patients receiving zanamivir.
There are no adequate studies in women for determining infant risk when using this medication during breastfeeding. Weigh the potential benefits against the potential risks before taking this medication while breastfeeding.
Interactions with Medicines
Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. Tell your healthcare professional if you are taking any other prescription or nonprescription (over-the-counter [OTC]) medicine.
Interactions with Food/Tobacco/Alcohol
Certain medicines should not be used at or around the time of eating food or eating certain types of food since interactions may occur. Using alcohol or tobacco with certain medicines may also cause interactions to occur. Discuss with your healthcare professional the use of your medicine with food, alcohol, or tobacco.
Other Medical Problems
The presence of other medical problems may affect the use of zanamivir. Make sure you tell your doctor if you have any other medical problems, especially:
- Allergy to lactose or milk proteins—Should not be used in patients with this condition.
- Brain disease (e.g., encephalopathy) or
- Mental illness or
- Seizures, or history of—Use with caution. May make these conditions worse.
- Heart disease—Safety of zanamivir for patients with this condition has not been established.
- Lung disease or breathing problems (e.g., asthma, chronic obstructive pulmonary disease or COPD)—Use is not recommended in patients with this condition.
Proper Use of zanamivir
Talk to your doctor about the possibility of getting a flu shot if you have not had one yet. Zanamivir works best if used as soon as possible after exposure to people who have the flu. If you already have the flu, continue using zanamivir for the full time of treatment even if you begin to feel better after a few days. This will help to clear up your infection completely. If you stop using zanamivir too soon, your symptoms may return. Zanamivir should be taken for 5 days.
Inhaled zanamivir is to be used only with a special inhaler (Diskhaler®). Do not mix zanamivir with other solutions. Do not use zanamivir in any nebulizer or mechanical ventilator.
Zanamivir usually comes with patient instructions. Read them carefully before using the medicine. If you do not understand the directions or you are not sure how to use the inhaler, ask your doctor to show you how to use it.
To load the inhaler:
- Pull off the blue cover. Make sure the mouthpiece is clean and free of foreign objects.
- Pull the white mouthpiece until the tray is extended.
- Hold the corners of the white tray and pull out gently until you can see all the raised ridges on the sides of the tray.
- Put your finger and thumb on the ridges, squeeze inward, and gently pull the tray out of the body of the inhaler.
- Place a disk on the wheel and then slide the tray back into the inhaler.
- To replace the empty disk with a full disk, follow the same steps you used to load the inhaler.
To use the inhaler:
- Hold the inhaler flat in your hand.
- A plastic needle will break the blister containing one inhalation of medicine. When the flap is raised as far as it will go, the blister will be pierced. Do not lift the flap if the cartridge is not in the inhaler. Doing this will break the needle and you will need a new inhaler.
- After the blister is broken open, close the lid. Keeping the inhaler flat and well away from your mouth, breathe out to the end of a normal breath.
- Raise the inhaler to your mouth, and place the mouthpiece in your mouth.
- Close your lips around the mouthpiece and tilt your head slightly back. Do not bite down on the mouthpiece. Do not block the mouthpiece with your teeth or tongue. Do not cover the air holes on the side of the mouthpiece.
- Breathe in through your mouth as steadily and as deeply as you can until you have taken a full deep breath.
- Hold your breath and remove the mouthpiece from your mouth. Continue holding your breath as long as you can up to 10 seconds before breathing out. This gives the medicine time to settle in your airways and lungs.
- Hold the inhaler well away from your mouth and breathe out to the end of a normal breath.
- Prepare the cartridge for your next inhalation. Pull the mouthpiece to extend the tray then push it in until it clicks. The disk will turn to the next dose. Do not pierce the blister until just before the inhalation.
- Take the second puff following exactly the same steps you used for the first puff.
- When you are finished, wipe off the mouthpiece and replace the cover to keep the mouthpiece clean and free of foreign objects.
If you are also using another inhaled bronchodilator (e.g., albuterol, Atrovent®, Combivent®, or Serevent®), use it before you use zanamivir.
The dose of zanamivir will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of zanamivir. If your dose is different, do not change it unless your doctor tells you to do so.
The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.
- For inhalation dosage form (powder):
- For prevention of flu in a household:
- Adults, teenagers, and children 5 years of age and older—Two puffs once a day for 10 days. Doses should be taken at the same time each day. Zanamivir must be started within 36 hours after the onset of signs and symptoms of the flu in a household.
- Children younger than 5 years of age—Use and dose must be determined by your doctor.
- For prevention of flu during community outbreaks:
- Adults, teenagers, and children 5 years of age and older—Two puffs once a day for 28 days. Doses should be taken at the same time each day. Zanamivir must be started within 5 days after the outbreak was identified in the community.
- Children younger than 5 years of age—Use and dose must be determined by your doctor.
- For treatment of the flu:
- Adults, teenagers, and children 7 years of age and older—Two puffs two times a day (about 12 hours apart in the morning and evening) for 5 days. Doses should be taken at the same time each day. Two doses should be taken on the first day of treatment whenever possible provided there are at least 2 hours between doses. Zanamivir must be started within 48 hours after the onset of signs and symptoms of the flu.
- Children younger than 7 years of age—Use and dose must be determined by your doctor.
- Canada: For treatment of flu:
- Adults, teenagers, and children 12 years of age and older—Two puffs two times a day (about 12 hours apart in the morning and evening) for 5 days. Two doses should be taken on the first day of treatment whenever possible provided there are at least 2 hours between doses. Zanamivir must be started within 48 hours after the onset of signs and symptoms of the flu.
- Children younger than 12 years of age—Use and dose must be determined by your doctor.
- For prevention of flu in a household:
If you miss a dose of zanamivir, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not double doses.
If you miss a dose or forget to use it, use it as soon as you can, except if it is less than 2 hours before your next dose. Use your next dose at the normal time. Do not use extra medicine to make up for a missed dose.
Keep the medicine in the foil pouch until you are ready to use it. Store at room temperature, away from heat and direct light. Do not freeze.
Keep out of the reach of children.
Do not keep outdated medicine or medicine no longer needed.
Ask your healthcare professional how you should dispose of any medicine you do not use.
Precautions While Using zanamivir
It is very important that your doctor check your or your child's progress after treatment. This is to make sure that the infection is cleared up completely, and to allow your doctor to check for any unwanted effects.
Zanamivir is not a substitute for an annual flu shot. It also will not keep you or your child from getting a bacterial infection that starts with flu-like symptoms.
Zanamivir may cause people with lung disease (e.g., chronic obstructive lung disease or asthma) to have shortness of breath, trouble breathing, or wheezing. If you have these symptoms after using zanamivir, stop using zanamivir and call your doctor right away.
Bronchospasm (wheezing) is a risk for patients with asthma or chronic respiratory disease. Always have a fast-acting inhaled bronchodilator available for your use.
Zanamivir may cause serious allergic reactions, including anaphylaxis. Anaphylaxis can be life-threatening and requires immediate medical attention. Stop using zanamivir and call your doctor right away if you or your child have itching, hives, hoarseness, trouble breathing, trouble swallowing, or any swelling of your hands, face, or mouth while you are using zanamivir.
Zanamivir may cause some people, especially children and teenagers, to be agitated, irritable, or display other abnormal behaviors, which may result in injury. If you, your child, or your caregiver notice any of these side effects, tell your doctor or your child's doctor right away.
Make sure your doctor knows if you or your child plan to get the live nasal flu vaccine (FluMist®) before you start using zanamivir. You should not receive the vaccine within two weeks before or 48 hours after using zanamivir.
If your or your child's symptoms do not improve after you or your child finish taking the medicine, or if they become worse, check with your doctor.
Zanamivir Side Effects
Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.
Check with your doctor immediately if any of the following side effects occur:
- dizziness and fainting
- fast, slow, or irregular heartbeat
- flushing or reddening of the skin
- increased sensitivity to sunlight
- itching, pain, redness, swelling, or watering of the eye or eyelid
- joint pain
- severe skin rash or hives
- shortness of breath or troubled breathing
- swelling or puffiness of the face
- swollen glands or tightness in the throat
- tightness in the chest or wheezing
Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:
- Change in hearing
- cough producing mucus
- ear drainage
- ear, nose, and throat infections
- fever or chills
- nasal signs and symptoms
- pain and pressure over cheeks
- pain in the ear
- shortness of breath
Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.
Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.
Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.
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More about zanamivir
- Zanamivir Side Effects
- During Pregnancy or Breastfeeding
- Dosage Information
- Drug Interactions
- En Español
- 3 Reviews
- Drug class: inhaled anti-infectives
Other brands: Relenza