Q: My 3-year-old had Influenza A and the fever dropped, but a 40°C (104°F) high fever returned after 5 days. Is this normal or should we see a doctor?
- Myeongchan Kim, MD
- Jun 14
- 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:
My 3-year-old child was diagnosed with Influenza A on Monday. After receiving IV fluids, the fever seemed to be well under control. However, starting on Friday (5 days later), a high fever of up to 40°C (104°F) has suddenly returned. Can a flu-related fever spike this high again after subsiding? Could there be another cause, and should we visit the hospital?
Answer:
I understand how worried you must be to see your child experience a recurrent 40°C (104°F) high fever five days after being diagnosed with Influenza A.
⚠️ A recurrent high fever after initial improvement requires immediate medical re-evaluation.
Here are the possible causes of a fever returning after a flu infection:
Secondary Bacterial Infection: This is the most common cause and can include conditions like pneumonia or otitis media (middle ear infection).
Double-Peak Fever Pattern: While relatively rare, the flu virus itself can sometimes cause a biphasic (double-peaking) fever pattern.
Viral Co-infection: Your child may have contracted a new, different virus while their immune system was vulnerable.
Dehydration or Other Complications.
You should visit a hospital or urgent care immediately, especially if you notice any of the following danger signs:
Fast, labored, or difficult breathing
Chest pain or a severely worsening cough
Pulling or rubbing the ears while crying (signs of an ear infection)
Refusal to drink fluids or a noticeable decrease in urine output
When you go to the hospital, please prepare the following to share with the doctor:
A record of the fever pattern (when it spiked, when it dropped, and recent temperatures)
A list of all medications your child is currently taking
Any newly developed or changing symptoms
A high fever returning 3 to 5 days after a flu diagnosis carries a high probability of a secondary bacterial infection, which may require a prescription for antibiotics. Please make sure to have your child evaluated by a pediatrician today for an accurate examination and proper treatment.
For extra peace of mind and clear guidance when tracking your child's symptoms, the FeverCoach app is always there to help.
