Quick answer: Antiviral medicines like oseltamivir (Tamiflu) and baloxavir (Xofluza) work best when started within 48 hours of your first flu symptoms. They can shorten the flu by about a day and lower the risk of complications. They are recommended for anyone hospitalized and for people at higher risk, and may be prescribed to healthy people seen early. Urgent care providers can prescribe them after a quick exam or flu test.
When it comes to flu treatment, timing matters. Here’s how antivirals work, who should take them, and why getting seen early makes a difference.
What do flu antivirals do?
Antivirals stop the flu virus from multiplying in your body. They don’t cure the flu instantly, but they can:
- Shorten symptoms, typically by about 1 day
- Reduce the risk of complications like pneumonia and ear infections
- Lower the chance of hospitalization in high-risk patients
Antivirals are different from antibiotics. Antibiotics don’t work on viruses like the flu (read can urgent care prescribe antibiotics?).
Why the 48-hour window matters
The flu virus multiplies fastest in the first 1 to 2 days. Starting an antiviral during that time gives it the best chance to help. That’s why it’s worth getting a rapid flu test as soon as symptoms hit, rather than waiting to see if you get better. Track where you are with flu symptoms day by day.
For people who are hospitalized, very sick or at high risk, antivirals may still help even after 48 hours.
Common flu antivirals
| Medicine | How it’s taken | Notes |
|---|---|---|
| Oseltamivir (Tamiflu) | Pill or liquid, twice a day for 5 days | Approved for all ages, including infants; most common choice |
| Baloxavir (Xofluza) | Single dose | For otherwise healthy people 5 and older; not for pregnancy |
| Zanamivir (Relenza) | Inhaled, twice a day for 5 days | Not for people with asthma or COPD |
| Peramivir (Rapivab) | One IV dose | Usually given in hospital settings |
Your provider will choose the right option based on your age, health and insurance coverage.
Who should get antivirals?
- Strongly recommended: people at higher risk, including adults 65+, children under 5, pregnant people and people with chronic conditions
- Strongly recommended: anyone hospitalized or with severe illness
- May be considered: healthy adults and children seen within 48 hours, or those who live with high-risk family members
For children, read flu in kids.
Side effects
Tamiflu’s most common side effects are nausea and vomiting, which are less likely if you take it with food. Rarely, children and teens may have unusual behavior; contact a provider if you notice this.
How to get antivirals fast
- Walk in: visit PACS in Alexandria or Ruther Glen for a test and prescription in one visit
- By video: a telehealth visit can lead to a prescription sent to your pharmacy when appropriate
Frequently asked questions
Can I get Tamiflu without a test?
Sometimes. During flu season, a provider may diagnose flu based on your symptoms, especially if you’re high-risk. Testing helps confirm the diagnosis.
Is it worth taking Tamiflu after 48 hours?
For high-risk or very sick patients, yes, it may still help. For healthy adults, the benefit is smaller after 48 hours.
Can Tamiflu prevent the flu?
Yes. It’s sometimes prescribed to prevent flu after close exposure, especially for high-risk people. It doesn’t replace the flu shot.
How much does Tamiflu cost?
Generic oseltamivir is widely available and often covered by insurance. Prices vary by pharmacy.
Where can I learn more?
See the CDC’s antiviral guidance at cdc.gov/flu.
Get care today at PACS Urgent Care
Walk in or book online at our Alexandria flu clinic (3481 N Beauregard St, open 7 days, 8 AM to 8 PM) or book at our Ruther Glen flu clinic (17067 Merchants Dr, Monday to Friday 8 AM to 8 PM, Saturday and Sunday 9 AM to 5 PM). Prefer to stay home? Start with a telemedicine visit.
This article is general information and is not a substitute for advice from your own clinician.
