The Centers for Disease Control and Prevention (CDC) usually blasts us with one message at the start of flu season: Get your flu shot. Now the CDC is adding another message: Take an antiviral medication if you get the flu. Why the two-pronged approach?

The flu season has been a real doozy this year, thanks to a particularly potent strain of flu virus that is making its way across the country called H3N2. (The flu is not one virus but a group of related influenza viruses, with some strains stronger than others.) As in years past, whenever the potent H3N2 strain shows up, the number of people who get sick from the flu increases. Hospital and death rates from the flu among young children and older adults also go up, in some cases nearly doubling. 

Adding insult to injury, this year’s flu shot seems to have missed the mark. The CDC makes educated guesses about which strains will be prevalent each year and builds a vaccine against those. However, this year’s vaccine doesn’t protect well against H3N2 (though the CDC still recommends getting a flu shot to protect against other strains).

This perfect viral storm has already led to 26 flu-associated deaths in children this flu season, according to the CDC.

What to do if you get the flu

The CDC has sent out an advisory stating that anyone who has flu symptoms and is at high risk of complications should take Tamiflu (oseltamivir) or Relenza (zanamivir), the two antiviral medications approved to treat the flu. These drugs can reduce complications, cut the time you’re sick by one to two days and possibly make flu symptoms milder. Tamiflu is approved to treat flu in children 2 weeks and older; Relenza can be used with kids age 7 and older, per the CDC website. For the most benefit, the medications should be started within 48 hours of developing the flu. People considered at high risk for complications include:

  • Adults 65 and older
  • Children younger than 5 years old, and particularly children younger than 2
  • Pregnant women and postpartum women who gave birth within two weeks of falling ill with the flu
  • American Indians and Alaska Natives
  • Anyone with chronic health conditions, including asthma, lung disease, diabetes, heart disease, kidney and liver disorders. A full list can be found on the CDC’s flu webpage

Antiviral medications are underused in high-risk populations. This leaves many people at unnecessary risk. “There’s low awareness of the CDC recommendations and there’s a perception that the drugs don’t work,” says Angela Campbell, MD, MPH, a medical officer at the CDC. “And a lot of patients don’t come in within the 48 hour window when it’s the most beneficial, so many feel they’ve missed the window,” she says. The fact is, for high-risk patients, taking the medication at any point is better than not taking it all.

“Physicians should be aware that all hospitalized patients and all outpatients at high risk for serious complications should be treated [with antivirals] as soon as possible,” says Joe Bresee, MD, branch chief in CDC’s Influenza Division. He recommends treatment whether someone has had the flu shot or not, and not waiting until the flu has been confirmed by blood tests. Studies have shown that in people with underlying medical conditions, antivirals can reduce the chances of developing pneumonia and being hospitalized.

If you’re low-risk, the CDC leaves the decision to take antivirals up to you and your doctor. People who are low-risk are not likely to have serious complications, so the CDC doesn’t urge them to take antivirals. But if you want relief sooner (and who doesn’t?), it may be a good idea.

Common side effects reported with Tamiflu and Relenza include nausea and vomiting. But “common” doesn’t mean they’re likely to happen to you. For instance, in clinical studies, vomiting occurred in nine percent of adults with flu who took Tamiflu compared to three percent of those who took a placebo drug; in children, 15 percent had vomiting compared to nine percent in those who took placebo. These side effects can be reduced if the medication is taken with food, and they usually subside after a day or so, according to Campbell. Other side effects, which are even less common, include dizziness, runny or stuffy nose, cough, diarrhea and headache.

Laurie Tarkan is an award-winning health journalist for the New York Times, national consumer magazines and websites.