Q&A: Antiviral Medications

Vaccines are the first line of defense against the seasonal and H1N1 flu viruses, but there are other options for preventing and treating the flu, too. This Q&A answers common questions about antiviral drugs, including who should take them, how effective they are and how they work.

What are antiviral drugs, and how do they work?

Prescription antiviral drugs are designed to slow the spread of influenza viruses. In doing so, they can help to prevent the flu or at least reduce its duration and the severity of its symptoms.

What antiviral drugs are recommended?

The Centers for Disease Control and Prevention (CDC) recommends treatment with two particular antiviral medications: oseltamivir (Tamiflu®) and zanamivir (Relenza®). Both are used to treat seasonal and H1N1 flu viruses. Oseltamivir comes as a capsule or liquid, and zanamivir comes as an inhaled powder.

Who should take antiviral drugs?

The CDC prioritizes groups for treatment of seasonal flu with antiviral drugs. Many people with the flu — particularly those with mild cases — recover without the drugs, but they can help people at higher risk avoid serious complications. These include:

• People with severe flu cases, including those who have been hospitalized
• People with the flu who are naturally at a higher risk, including children younger than 2, adults older than 65, pregnant women and people with chronic medical or immunosuppressive conditions
• Youth under 19 who receive long-term aspirin therapy

Doctors may prescribe antiviral drugs for patients who aren’t in these groups, of course, particularly if they have suspected or confirmed flu and symptoms of respiratory-tract illnesses.

When should someone start taking antiviral drugs? Is it ever too late?

Studies show that antiviral treatment works best when started within 48 hours of the onset of illness. However, studies also have shown the drugs to provide benefit to hospitalized patients who start taking them after that time frame, too.

How long does treatment last? Should I stop taking the drugs if my symptoms go away?

Doctors typically prescribe five days' worth of treatment, but the course may be longer for severe cases. Even if you start to feel better, you should take the full course of treatment as prescribed.

If I’ve been exposed to the flu, should I take antivirals?

If you are healthy, the answer is likely no. The CDC discourages this usage.

What drugs are available for children, and are they safe?

The same antiviral drugs, oseltamivir and zanamivir, are available for use in children. Oseltamivir comes as a liquid or capsule in children’s dosages and is approved by the FDA for children 1 year or older — and also for children under a year in an emergency. Zanamivir is an inhaled powder and is approved for children 7 years or older, as long as they do not have other respiratory conditions, such as asthma, or heart conditions.

If oseltamivir is unavailable in the children’s doses, adult dosages can be prepared into a pediatric formulation by a healthcare professional. Likewise, if the liquid is not available and your child cannot swallow capsules, the children’s capsules of oseltamivir may be opened and mixed with sweetened liquids.

Ask your doctor or pharmacist about possible side effects for these drugs.

Can I have the flu vaccine and still take antiviral drugs?

Antiviral drugs can be taken safely and effectively along with the inactivated form of a flu vaccine. However, the nasal spray form of vaccine — live attenuated influenza vaccine, or LAIV — can be weakened by antiviral drugs. Consult your physician about taking antiviral drugs if you have received or plan to receive LAIV.

Read more about antiviral drugs at the CDC’s website.

» Return to flu information page.

Published Oct. 26, 2009