Doctors prescribe antiviral medications to treat the flu, with four FDA-approved options currently recommended in the United States. The most common is oseltamivir (Tamiflu), an oral medication taken twice daily for five days. These drugs work best when started within 48 hours of your first symptoms, and they typically shorten the illness by about one to two days.
The Four Approved Flu Antivirals
The CDC recommends four antiviral medications for treating influenza. Three of them work by blocking an enzyme the virus needs to spread from cell to cell in your body: oseltamivir (Tamiflu), zanamivir (Relenza), and peramivir (Rapivab). The fourth, baloxavir (Xofluza), works differently. It interferes with the virus’s ability to copy itself inside your cells.
Two older medications, amantadine and rimantadine, are no longer recommended because circulating flu strains have developed high levels of resistance to them.
Oseltamivir: The Most Common Prescription
Oseltamivir is by far the most frequently prescribed flu antiviral. It comes as a capsule or liquid suspension, making it usable across nearly all age groups. Adults and teenagers take 75 mg twice a day for five days. Children one year and older receive a weight-based dose, typically between 30 and 75 mg twice daily for the same five-day course. Even infants as young as two weeks old can receive it, with dosing determined by their weight.
The most common side effect is nausea and vomiting. In clinical trials, about 10% of adults experienced nausea and 9% experienced vomiting, compared to roughly 6% and 3% on placebo. Children had slightly higher rates of vomiting (14% versus 8.5% on placebo). Taking the medication with food can help reduce stomach upset. Only about 1% of people in trials stopped the drug because of these symptoms.
There have been rare reports of neuropsychiatric effects like confusion or unusual behavior, mostly among Japanese adolescents and adults. Multiple analyses have found no clear causal link, but the FDA still advises monitoring for abnormal behavior during treatment.
Baloxavir: The Single-Dose Option
Baloxavir (Xofluza) stands out because it requires just one dose. Instead of five days of pills, you take a single tablet and you’re done. In the CAPSTONE-1 clinical trial, it reduced flu symptom duration from an average of about 80 hours to roughly 54 hours, a gain of just over a day compared to no treatment.
This convenience makes baloxavir appealing, especially for people who struggle with multi-day medication schedules. It’s approved for otherwise healthy people ages 5 and older, as well as for those at high risk of complications ages 12 and older.
Less Common Options
Zanamivir (Relenza) is an inhaled powder, which means you breathe it into your lungs using a disk inhaler. It’s generally not a first choice because it requires proper inhaler technique and isn’t suitable for people with asthma or other chronic lung conditions.
Peramivir (Rapivab) is given as a single IV infusion. It’s reserved for situations where someone can’t take medication by mouth, such as hospitalized patients who are too sick to swallow pills or keep them down.
The 48-Hour Window
All flu antivirals work best when started within 48 hours of symptom onset. The earlier you begin, the more viral replication the drug can suppress before your body’s immune response peaks. Starting treatment on day one tends to produce a bigger benefit than starting on day two.
After 48 hours, the benefit drops significantly for most otherwise healthy people. However, doctors may still prescribe antivirals beyond that window for hospitalized patients or people at high risk of serious complications, where even a modest reduction in viral activity can make a meaningful difference.
Who Gets a Prescription
Not everyone who catches the flu needs antivirals. Many healthy adults and older children recover on their own within a week or so. Doctors are more likely to prescribe antivirals for people at higher risk of flu complications. This includes adults 65 and older, children under 5 (especially those under 2), pregnant women, and people with chronic conditions like asthma, diabetes, heart disease, or weakened immune systems. Anyone sick enough to be hospitalized with flu will typically receive antivirals regardless of how long symptoms have been present.
If you’re otherwise healthy and your symptoms are manageable, your doctor may decide that antivirals aren’t necessary and instead recommend supportive care to manage your symptoms at home.
Over-the-Counter Medications for Symptom Relief
Whether or not you receive a prescription antiviral, doctors commonly recommend over-the-counter medications to help you feel better while your body fights the virus. These don’t treat the flu itself, but they address the misery.
- Fever and body aches: Acetaminophen (Tylenol) or ibuprofen (Advil, Motrin) are standard choices. For children, use the infant or pediatric versions. Aspirin should never be given to children or teenagers with the flu because of the risk of Reye’s syndrome.
- Congestion: Saline nasal sprays can help relieve stuffiness without medication. Decongestants are an option for adults and children over 5.
- Cough: Over-the-counter cough suppressants and antihistamines may ease symptoms in adults and children 5 and older, though evidence for their effectiveness is mixed.
Staying hydrated matters more than most people realize. Fever and sweating deplete fluids quickly, and dehydration can make fatigue, headaches, and muscle aches feel significantly worse. Water, broth, and electrolyte drinks all help.
Antibiotics Don’t Treat the Flu
The flu is caused by a virus, so antibiotics have no effect on it. Doctors will only prescribe antibiotics if you develop a secondary bacterial infection on top of the flu, such as bacterial pneumonia or a sinus infection. If your symptoms improve and then suddenly worsen again after several days, that pattern can signal a bacterial complication worth getting checked out.