Q: Can an Influenza A infection last for over two weeks, and is Tamiflu still effective?
- Myeongchan Kim, MD
- Jun 30
- 2 min read
Updated: Jul 8
Medically reviewed by Sang Hyun Ahn, MD
Content edited by Myeongchan Kim, MD
This post is a dramatization of a question and answer session experienced by our actual medical reviewers. Please note that this content is for informational purposes only and does not constitute medical advice. Always consult with a qualified healthcare professional for any health concerns or before making any decisions related to your health or treatment.
Question:
I heard that Tamiflu is only effective if taken within 48 hours of flu symptom onset. My child developed a fever about two and a half weeks ago and has been continuously taking medication for severe bronchitis. The bronchitis was gradually improving with the medication, but suddenly, a high fever spiked again a few days ago. We got a flu test, and it came back positive for Influenza A. Is it possible that the Influenza A infection started over two weeks ago and has lasted until now? We didn't do a flu test back when the initial fever started.
Answer:
I understand your concern about the duration of the flu virus and the timeline of your child's illness.
Possibility of the initial infection lasting until now:
It is highly unlikely. Influenza A typically resolves within 5 to 7 days, or up to 2 weeks at the very longest. A duration of over 16 days is simply too long for a continuous, active flu infection.
Analysis of the current situation:
Here are the more likely clinical scenarios:
Most likely scenario: The illness that started two and a half weeks ago was a completely different viral bronchitis, and the sudden high fever a few days ago marks a brand-new Influenza A infection.
Alternative scenario: Your child contracted Influenza A very recently (with asymptomatic or mild symptoms initially), and the symptoms suddenly worsened a few days ago, leading to the positive test.
Regarding Tamiflu administration timing:
You are correct that antiviral medications like Tamiflu are most effective when started within 48 hours of symptom onset. However, in high-risk groups or severe cases, it can still be beneficial even if administered after the 48-hour window.
What you should do now:
It is highly probable that your child's immune system was weakened by the recent bout of severe bronchitis, making them more susceptible to catching the flu. To ensure a safe recovery, please take the following steps:
Consult your pediatrician immediately to evaluate your child's current condition and determine if Tamiflu is necessary at this stage.
Check with your doctor to confirm that any new flu medications are safe to take alongside the existing bronchitis medications.
Ensure your child gets plenty of rest and stays well-hydrated.
Wishing your child a smooth and speedy recovery. Please see your doctor for an in-person evaluation to finalize the best treatment plan.
For extra peace of mind and clear guidance when tracking your child's symptoms, the FeverCoach app is always there to help.
