What You Should Know About Flu Antiviral Medications

Flu season is here, which means it is time to protect yourself and your loved ones from all the germs that are going around. Your first stop on the road to prevention should always be getting a yearly flu vaccine in the fall. But it is also important to know that several treatment options are available if you do become sick.

If you start having symptoms like fever, body aches, cough and congestion, walk into any CityMD urgent care or Book a Visit for a specific time – to get a timely flu test and treatment. You can also make an appointment with a primary care physician at Summit Health.

This season, the Centers for Disease Control and Prevention (CDC) recommends four antiviral medications approved by the U.S Food and Drug Administration (FDA) to treat flu.

Shannon Rosario, PharmD, BCACP, who specializes in ambulatory clinical pharmacy services at Summit Health, provides answers to the most common questions about flu antiviral medications. Find out below who should take antivirals, when they should be started, how they work and potential side effects.

Q. What medications are available to treat the flu? What ages are eligible and how long do you need to take them?

There are four FDA-approved antiviral drugs recommended by the CDC this season:

• Oseltamivir (Tamiflu®): Available as pill or liquid and can be used by adults and children of all ages. It is preferred for the treatment of flu in pregnant people and children.
• Zanamivir (Relenza®): Available as an inhaler and is used by adults and children 7 years and older. It is not recommended for people with respiratory diseases like asthma or chronic obstructive pulmonary disease (COPD).
• Peramivir (Rapivab®): Given through an IV by a healthcare provider and is used by adults and children 6 months of age and older.
• Baloxavir (Xofluza®): Available as a pill and can be used by adults and children 5 years and older. It is not recommended in pregnancy or breastfeeding.

Oseltamivir (Tamiflu®) and zanamivir (Relenza®) are both taken for 5 days for the treatment of flu. Peramivir (Rapivab®) is given once by IV and baloxavir (Xofluza®) is given as a one-time oral dose.

Q. How do antivirals work, and are they effective?

Antiviral flu medications work by preventing the flu virus from multiplying in your body. Early antiviral treatment can shorten the length of fever and other symptoms by about one day and may reduce the risk of some complications from influenza.

Q. Do you need to take antivirals within the first 48 hours? Will they be ineffective if they are taken after that period of time?

Antivirals work best when they are taken within 48 hours of flu symptom onset. Starting Oseltamivir (Tamiflu®) after 48 hours can be considered in hospitalized patients, patients with severe/complicated illness, or patients at a higher risk for influenza complications.

Q. What are the most common side effects?

Side effects vary for each medication. The most common side effects of oseltamivir (Tamiflu®) are nausea and vomiting, which are usually not severe and can be decreased by taking oseltamivir (Tamiflu®) with food. Zanamivir (Relenza®) can cause bronchospasms, or a tightening of the airways in the lungs, and peramivir (Rapivab®) and baloxavir (Xofluza®) can cause diarrhea.

Q. Can antiviral flu medications be used prophylactically to prevent the flu in someone who has been exposed to it?

Annual vaccination is the best method for preventing influenza. Antiviral medications should not be used for routine prophylaxis or prevention in the community. Prophylaxis can be considered after a household exposure for patients at high risk for influenza complications for whom influenza vaccination is contraindicated, unavailable or expected to have low effectiveness. 

Oseltamivir (Tamiflu®), zanamivir (Relenza®) and baloxavir (Xofluza®) are approved for prophylactic use.

Q. Should elderly adults or people with compromised immune systems take antivirals? Is there anyone who should not take medication for the flu?

All four antiviral medications recommended by the CDC can be used in elderly adults. Patients with compromised immune systems can take antivirals, but the CDC does not recommend the use of baloxavir (Xofluza®) for the treatment of influenza in severely immunosuppressed patients.

Patients should not take an antiviral medication if they are allergic to the active ingredient or any component of the medication. Check with your doctor if you have any questions.