New flu drugs: what works, how they differ, and when to use them

Flu doesn't always have to run its full course. Newer antivirals can shorten symptoms, reduce complications, and lower the chance you spread the virus. If you or someone you care for is high-risk, knowing how the latest drugs work makes it easier to get the right treatment fast.

What’s new and how these drugs work

Baloxavir marboxil (brand name Xofluza) is one of the most talked-about recent options. It blocks a viral enzyme called endonuclease, which the virus needs to copy itself. The big plus: a single oral dose can cut symptoms faster than no treatment and often reduces how much virus you shed. Best results come when it’s given within 48 hours of symptoms starting.

Favipiravir (Avigan) works differently — it messes up the virus’s RNA polymerase, stopping it from making copies. Favipiravir has been used in some countries for severe influenza or during outbreaks, but it’s not approved everywhere. It can cause birth defects, so pregnancy testing and contraception are important if this drug is considered.

Older drugs still matter. Oseltamivir (Tamiflu), zanamivir (Relenza), and peramivir (Rapivab) are neuraminidase inhibitors that reduce the length and severity of flu when started early. Peramivir is an IV option used mainly in hospitals.

When to treat, safety, and resistance

Timing matters. Antivirals work best when started within 48 hours of symptom onset. For people at high risk — young children, older adults, pregnant people, and those with chronic conditions — doctors sometimes start treatment even after 48 hours if the illness is severe.

Side effects are usually mild: nausea, headache, or diarrhea. Baloxavir can cause some stomach upset and, rarely, allergic reactions. Favipiravir’s major concern is harm to a fetus, so it’s avoided in pregnancy. Resistance can develop with any antiviral. Baloxavir resistance has been reported in some cases, so doctors watch how patients respond and may change treatment if needed.

Testing helps, but don’t wait if someone is very sick. Rapid flu tests can guide treatment, but clinical judgment is key — especially for high-risk patients.

Access and cost vary. Many antivirals need a prescription. Telehealth, urgent care, or your primary doctor can prescribe them. Prices differ by drug and location; check discount programs and your insurance plan.

Researchers are also testing monoclonal antibodies and new host-targeted drugs that might prevent or treat flu in different ways. Those options aren’t routine yet, but they’re worth watching, especially for high-risk groups.

If you want practical next steps: if symptoms start and you’re high-risk or very sick, contact a clinician fast. Ask about baloxavir and oseltamivir, mention any pregnancy or medication concerns, and follow dosing instructions exactly. Staying informed helps you get treatment that actually helps — and keeps complications less likely.