Flu cases are rising. Here’s how to treat it and when antivirals work best

Flu season is peaking. Learn how antiviral treatments can shorten flu symptoms, when to get tested, and why vaccination still matters.

Flu cases are climbing across the United States as the season reaches its peak, and millions of people may get sick in the weeks ahead. If you catch the flu early, antiviral medications can help shorten how long symptoms last and reduce the risk of serious complications.

Influenza, commonly known as the flu, is entering its seasonal peak as the new year begins. Flu activity across the U.S. increased by about 15% in the final days of 2025, according to the U.S. Centers for Disease Control and Prevention (CDC).

If you think it’s too late to protect yourself this season, it may not be. Flu season often unfolds in two phases, driven by different virus types.

Influenza A typically peaks first, most often between December and January. A second wave, driven by Influenza B, usually peaks later — on average between February and April.

What to do if you think you have the flu

Common flu symptoms include high fever, chills, cough, body aches, fatigue, and a runny or congested nose. Some people, especially children, may also experience vomiting or diarrhea. The CDC notes that not everyone with the flu will develop a fever.

Over-the-counter flu tests are available at many pharmacies, and rapid tests at a doctor’s office can help confirm whether influenza is causing your symptoms. However, false negatives are common, especially very early or later in the illness. Testing is most accurate within the first three days of symptoms.

What are the treatment options for the flu?

If started as soon as possible, antiviral medications can shorten the duration of illness and may reduce the risk of complications. The CDC recommends starting antiviral treatment within one to two days of symptom onset for the greatest benefit.

This season, four FDA-approved antiviral drugs are recommended to treat influenza:

• Oseltamivir phosphate (available as a generic or under the brand name Tamiflu®)

• Zanamivir (Relenza®)

• Peramivir (Rapivab®)

• Baloxavir marboxil (Xofluza®)

Tamiflu is the most widely prescribed antiviral and is approved for patients as young as 14 days old, according to the American Academy of Pediatrics (AAP). It is taken as a pill or liquid twice daily for five days.

Peramivir is also approved for young children — as young as six months old — but is given intravenously by a health care provider, typically in hospital or outpatient settings.

Zanamivir is administered through an inhaler and is approved for patients 7 years and older. Like Tamiflu, it is taken over five days and is not recommended for people with certain respiratory conditions, such as asthma.

Baloxavir is the newest flu treatment, approved by the FDA in 2018. It is a single-dose oral medication for early treatment of flu in patients 5 years and older. It is not recommended for people who are pregnant, breastfeeding, or experiencing severe or complicated influenza.

Why prevention still matters

Getting a flu shot each year helps protect against both Influenza A and Influenza B. Even if vaccination does not completely prevent infection, it can reduce the severity and length of illness.

The AAP and the CDC recommend an annual flu vaccine for everyone 6 months and older.

"Each year, it is possible that flu, COVID-19, and other common viruses will spread at the same time," Dr. Kristina Bryant, a member of the AAP Committee on Infectious Diseases, said in a statement. "Sometimes, the vaccine is not an exact match with the strains in the community. But the vaccine still can protect against serious illness."

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