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Q: My 32-month-old has a high fever up to 39°C and lethargy. Should we get a flu test tonight or wait until tomorrow morning?

  • Myeongchan Kim
  • 2 days ago
  • 2 min read

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:

My 32-month-old daughter is currently taking medication, including antibiotics, for nasal symptoms. Today at 6:00 AM, her temperature was 38.2°C. I gave her a fever reducer at 38.4°C, and it dropped to 37.3°C. At 12:40 PM, it went up to 38.6°C, so I gave her another dose, and it went down to 37.7°C. However, at 4:20 PM, it spiked to 39.0°C, and I gave her another dose of the fever reducer.


I was initially planning to wait and take her for a flu test tomorrow, but whenever her fever spikes, she suddenly becomes extremely lethargic. After taking the fever reducer, she plays well for about an hour, but then her energy drops sharply again just before the fever returns.


I found a clinic that is open late. If we go for a flu test around 7:00 PM tonight, will the results be accurate if it is the flu? Or would it be better to wait and get tested tomorrow morning?


Answer:

It is completely understandable that you are worried about your daughter's recurrent high fevers and sudden drops in energy. Watching a child's condition fluctuate so rapidly with a fever can be very distressing.


Regarding the timing of the flu test:

• Flu tests are most accurate when performed 12 to 48 hours after symptoms begin.

• Since her fever started at 6:00 AM today, testing at 7:00 PM tonight (which is 13 hours after symptom onset) is an appropriate time and can yield reliable results.

• Antiviral medications (like Tamiflu) are most effective when started within 48 hours of symptom onset, so an early diagnosis is highly beneficial.


I strongly recommend taking her to the clinic tonight rather than waiting until tomorrow. This is advised because:

  1. She is experiencing a high fever (39.0°C) accompanied by sudden, severe lethargy.

  2. The duration of the fever reducer's effectiveness appears to be shortening.

  3. If it is the flu, starting early treatment is crucial for a smooth recovery.


When you visit the clinic, please be prepared to share:

• A brief fever log (times the fever spiked, the temperatures, and the exact times fever reducers were given).

• The names of the medications she is currently taking (including the antibiotics).

• An estimate of her fluid intake over the past day.


⚠️ Please head to the nearest emergency room immediately if you notice any of the following severe signs:

  • Her consciousness becomes cloudy or she becomes unresponsive.

  • Her breathing becomes rapid, heavy, or labored.

  • She has not urinated for more than 4 hours.


Because flu symptoms can progress rapidly in toddlers, having her evaluated by a doctor today is the safest and best course of action.



For extra peace of mind and clear guidance when tracking your child's symptoms, the FeverCoach app is always there to help.








 
 
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