Do I Need Antiviral Drugs If I Have the Flu?

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Just as antibiotics fight bacterial infections, so do antiviral drugs fight viral infections. Bacteria and viruses are very different organisms, and drugs that treat one do not treat the other. Two antiviral drugs, oseltamivir (Tamiflu), a pill taken by mouth, and zanamivir (Relenza), an inhaled medication, are particularly effective against the influenza viruses that cause the flu. Virtually every flu virus tested during this flu season has proven to be susceptible to these medications.

What are the potential benefits of taking antiviral drugs for the flu?

Both Tamiflu and Relenza work only if taken within 48 hours of developing symptoms of the flu. Fever, headache, body aches, sore throat, cough, and eye pain (such as burning, light sensitivity, and pain with eye movement) are all classic symptoms of the flu. If you start taking one of these medications within that 48-hour window, the benefits include:

  • A shorter duration of illness (typically 1-2 days shorter)
  • A shorter period in which you will be contagious and can spread the disease to others
  • A lowered risk of developing complications from the flu, primarily pneumonia

What are the complications of the flu, and am I at risk for them?

The major complication is pneumonia. Pneumonia caused by the flu virus itself is, fortunately, very rare. It’s characterized by a persistent fever, shortness of breath and lots of phlegm. Sometimes, bacteria make their way into lungs already vulnerable from the effects of the flu virus. In this scenario, patients start to get better, but then fever returns, along with the production of thick, discolored phlegm, and progressive shortness of breath. These patients usually require a chest x-ray and antibiotic therapy. There is a third pattern–a combination of the two types just described–which almost always requires hospitalization.

No one is impervious to these complications of the flu, but certain people are at increased risk, including those with: serious underlying health issues, such impaired immunity (from illness or certain medications); chronic lung disease; chronic heart disease; asthma; malignancy; poorly controlled diabetes; chronic kidney disease; and other debilitating illnesses. Pregnant women in their second and third trimesters are also at increased risk, as are very young children and the elderly.

Who should take antiviral drugs for the flu?

Initially, health care providers recommended antiviral medications only for people at high risk of developing flu-related complications. But now, they’re a treatment option for anyone with the flu, no matter their age or underlying health. Of course, this doesn’t necessarily mean that you should take antiviral therapy for the flu–be sure to talk to your health care provider to ensure you have all the information you need to make an informed decision.

Additionally, although they’re graded as “Pregnancy Category C” medications (meaning that a potential risk to the fetus can’t be ruled out), antiviral drugs are commonly prescribed to women at any stage of pregnancy, who–particularly during the second and third trimesters–are at an increased risk of complications from the flu. Nursing mothers can also be treated with antiviral drugs. We recommend antiviral therapy for anyone who is unvaccinated and who will have close contact with unvaccinated children two years old or younger.

I feel OK now, but I’ve been around people with the flu; should I take antiviral medication?

Preventive therapy with antiviral drugs is helpful for unvaccinated, healthy people who have been exposed to the flu (although the dose is different than it is for someone who has been infected). During a flu epidemic, antiviral drugs can help reduce the risk of getting the flu in the first place for people who are at high risk of developing flu-related complications. At the beginning of a flu outbreak in a nursing home or other chronic medical facility, for example, all residents are put on preventive antiviral therapy.

If you’re a healthy person who has had close exposure to someone (or multiple people) with the flu, you can certainly consider preventative antiviral therapy; alternatively, you can wait to see if you begin to show any symptoms of the flu, and then immediately start therapy with Tamiflu or Relenza.

What are the side effects of antiviral medications?

The vast majority of people experience no side effects at all. With Tamiflu, the most common side effects are gastrointestinal, such as nausea and vomiting, but fewer than 1 in 10 people develop any of these side effects at all. With Relenza, the inhaled medication, the most common side effect is spasm of your large airways that can mimic asthma; however, this generally only occurs in people with pre-existing asthma or underlying chronic lung disease. And although extremely rare, either medication can cause seizures and other neurologic and psychiatric side effects–but again, this is exceedingly rare.

How do I take the drugs, and how long must I take them?

The standard course is five days for both medications. Tamiflu is a pill that you take twice a day, and Relenza is an inhalant, which you take two times, twice a day. If you have underlying kidney failure, your health care provider will have to adjust the dosing schedule of Tamiflu (but not Relenza), and instead, you would take it in a single dose every other day for 10 days. Other dosage adjustments are made for young children.

What do I do if I’ve already had symptoms for over 48 hours?

Don’t worry; you will almost certainly be fine. But you should not take the antiviral medications. They will not be effective and you won’t experience any of the benefits mentioned above. Stay home, rest, and the worst symptoms will usually resolve within several days to a week. If, after a few days, you aren’t getting better–and particularly if you’re getting worse–contact your primary health care provider.

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The One Medical blog is published by One Medical, an innovative primary care practice with offices in Boston, Chicago, Los Angeles, New York, Phoenix, the San Francisco Bay Area, Seattle, and Washington, DC.

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