Antiviral treatment for flu

Who should get an antiviral

CDC recommends starting antiviral treatment as soon as possible for anyone with suspected or confirmed flu who:[1]

• is in the hospital with flu;
• has severe, complicated, or worsening illness, at any point in the illness; or
• is at higher risk of complications, such as adults 65 and older, young children, pregnant people, and people with conditions like asthma, diabetes, or heart disease.

For otherwise healthy people, a clinician can still prescribe an antiviral if it can be started within two days of getting sick.[1] Started in that window, treatment lessens symptoms and shortens illness by about a day.[3]

Timing

The two-day window applies to people who are otherwise healthy and have an ordinary course of flu. For people who are hospitalized, or whose illness is severe or getting worse, observational studies show benefit even when treatment starts after 48 hours, and CDC recommends treating them regardless of when symptoms began.[1][2]

The four FDA-approved flu antivirals

Special situations

Pregnancy and the 2 weeks after

Pregnant people and those up to two weeks postpartum are in a higher-risk group and should be treated promptly. Oral oseltamivir is preferred, at the same dose as for anyone else. Baloxavir is not recommended during pregnancy or breastfeeding.[1][2]

Children

Oseltamivir is dosed by weight and comes as a liquid. Children younger than 2 are a high-risk group and should be treated as soon as flu is suspected.[1][9] Baloxavir is not approved under age 5 because resistance emerged more often in younger children in trials.[5]

Never give aspirin or aspirin-containing products to anyone under 19 with flu: it can cause Reye syndrome, a rare but serious illness of the liver and brain.[12]

Kidney disease

Oseltamivir doses are reduced when kidney function is lower. Your clinician will adjust it; tell them about any kidney disease or dialysis.[4]

Severely weakened immune system

Oseltamivir is preferred. Baloxavir should not be used alone because resistance is more likely; a clinician may consider combining medicines.[2]

Side effects

The most common side effects of oseltamivir are nausea and vomiting, usually mild and less likely when it is taken with food. The label also notes rare reports of confusion or unusual behavior, mostly in children; flu itself can cause these, and the medicine's role has not been established.[4] Call your clinician if anything unusual happens.

After an exposure: preventing flu

Antivirals can also prevent flu after close contact with a sick person. This is mainly for people at very high risk (for example, a severely immunocompromised household member) for whom the vaccine is not an option or may not work well. It should start within 48 hours of the exposure and usually continues for 7 days after the last exposure.[9][1] For healthy people, CDC and IDSA generally prefer watching for symptoms and starting treatment early if they appear.[9]

Do the drugs still work?

Yes. Of more than 4,400 flu viruses CDC tested in the 2025–26 season, about 99% were susceptible to all four antivirals, and none showed reduced susceptibility to baloxavir.[10]

Taking care of yourself at home

• Rest and drink plenty of fluids. Acetaminophen or ibuprofen can ease fever and aches if they are safe for you.
• Stay home while you are sick. You can go back to normal activities once, for at least 24 hours, your symptoms are improving overall and you have had no fever without fever-reducing medicine. Take extra precautions for the next 5 days, such as a well-fitted mask around others.[11]
• Watch for the emergency warning signs, especially a fever or cough that gets better and then comes back worse, which can signal pneumonia.

Longer read: TeleDirectMD's flu treatment guide covers medicines, home care, and recovery week by week.