Q: Can we take a flu test with a mild fever of 37.9°C, muscle aches, and a cough?
- Myeongchan Kim, MD
- Jul 2
- 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 have a question about the flu. Yesterday, my child had a fever of 37.9°C, accompanied by muscle aches and a cough. Can we still get a flu test done? Will the test come back negative just because it is not a high fever?
Answer:
Thank you for your inquiry regarding flu testing. Although 37.9°C is considered a mild fever, a flu test can certainly be performed and yield accurate results.
Here is some important information regarding flu testing:
When to take the flu test
• The test is most accurate when performed 12 to 48 hours after symptoms begin.
• The influenza virus can be successfully detected even without the presence of a high fever.
• The combination of muscle aches, a cough, and a mild fever is highly indicative of the flu.
Why testing is recommended
• Early diagnosis is crucial because antiviral medications (such as Tamiflu) are most effective when started within 48 hours of symptom onset.
• Confirming the diagnosis helps take measures to prevent spreading the virus to other family members.
• Flu symptoms can escalate very suddenly, so catching it early is beneficial.
Precautions
• It is possible to have the flu even if the initial test result is negative (known as a false negative).
• If symptoms worsen after a negative result, a retest may be necessary.
• Please make sure both you and your child wear a mask when visiting the clinic.
Please keep in mind that younger children are at a higher risk for flu-related complications and require proactive testing and careful treatment. I highly recommend visiting your pediatrician promptly for a thorough in-person evaluation and proper medical guidance.
For extra peace of mind and clear guidance when tracking your child's symptoms, the FeverCoach app is always there to help.
