Flu season is in full swing. When do you need Tamiflu?

The flu is raging across the United States — and the Centers for Disease Control and Prevention expects cases will remain high over the next few weeks.

“It’s out of control,” said Dr. Sean Liu, an associate professor of infectious diseases at the Icahn School of Medicine at Mount Sinai in New York City. The CDC estimates that there have been at least 12 million flu infections so far this season, leading to 160,000 hospitalizations and 6,600 deaths.

Doctors frequently prescribe Tamiflu, an antiviral medication, to people who are at high risk of becoming seriously ill from the flu. The drug can ease symptoms and help people recover a bit faster. But there’s a catch: The medication works best if people take it soon after they feel sick, and it can be tricky to decipher whether a pesky cough or sneeze is the flu or another virus.

This flu season, however, new at-home rapid tests can detect both COVID and the flu and can help you determine whether you should ask a doctor about Tamiflu. Here’s what else to know about the drug.

How does Tamiflu work?

Tamiflu works against both influenza A and influenza B viruses. The drug, which can be taken as a liquid or a pill, blocks the flu virus from spreading in the body.

“It’s not a magical medication,” said Dr. William Schaffner, an infectious disease specialist at Vanderbilt University Medical Center. “It doesn’t make you instantly better, able to leap tall buildings.” But the drug can speed up a patient’s recovery by about a day, which might not sound like much, but can get people back to work or school more quickly.

And by limiting the spread of flu virus in someone’s body, the drug could help prevent an infection from developing into a more severe illness like pneumonia, Schaffner said.

It can be tricky to measure just how effective Tamiflu is, though, in part because many people recover from the flu on their own, he added.

Researchers have debated whether Tamiflu prevents flu deaths or hospitalizations, for example. But some evidence suggests that it may reduce the risk of death among hospitalized adults, especially when taken early.

Who should take Tamiflu?

Not everyone who comes down with the flu should take the drug. The CDC recommends the medication for people who are at high risk for complications from the flu, which includes adults who are 65 and older, children younger than 2, pregnant women and people who are immunocompromised. The agency also recommends the drug for patients with certain chronic conditions, like diabetes, asthma and lung and heart disease.

Doctors also prescribe Tamiflu to people who are hospitalized or very ill from the flu. And they sometimes give the medication to everyone in a setting like a nursing home, where the virus can spread rapidly during an outbreak.

The CDC recommends Tamiflu for anyone infected with avian influenza, also known as bird flu, and for people who have been exposed to those infected with bird flu.

What are the side effects?

It can be hard to differentiate the side effects of Tamiflu from symptoms of the flu itself. Roughly 10% to 20% of patients who take the drug experience nausea and vomiting, said Dr. Sean O’Leary, a professor of pediatric infectious diseases at the University of Colorado School of Medicine.

There have been rare reports of side effects, including hallucinations and delirium, among children in Japan who took Tamiflu. But the flu itself can also cause those issues, and doctors and health agencies have emphasized that Tamiflu is safe.

The drug “has been out for a long time, and we’ve got a really good handle on its safety profile,” said Dr. John Bradley, the medical director of infectious diseases at Rady Children’s Hospital-San Diego.

Are there other drugs that treat the flu?

The CDC has recommended three other antiviral medications for use this flu season:

• Relenza, an inhaled drug for people 7 and older who do not have asthma or other breathing issues.
• Rapivab, an intravenous drug for people 6 months and older.
• Xofluza, a pill for those 12 and older and for children between the ages of 5 and 11 who do not have any chronic health conditions. The CDC does not recommend Xofluza for pregnant or breastfeeding women.

Doctors prescribe these drugs less often, but they can be helpful for patients who cannot take Tamiflu, or useful when Tamiflu is not available. Some doctors may use Xofluza because it is a single dose.

While vaccines do not treat the flu, doctors stressed that a flu shot offers valuable protection and can reduce the risk of developing severe symptoms and dying. It’s not too late to get a flu shot, O’Leary said.

Given the choice between Tamiflu when you get sick, or a flu shot to prevent sickness in the first place, “I would take the influenza vaccine 100 times out of 100,” O’Leary said.