Q: My 8-month-old had a 39°C fever over the weekend but is now playing well. Should we see a doctor?

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 8-month-old boy (9.8 kg) had a fever of 39.0°C on Saturday afternoon. I tried giving him a fever reducer, but he refused it, so he only swallowed about 1 ml. His temperature dropped slightly to 38.7°C. His formula intake has been very low lately—only 250 ml the day before and 160 ml on Saturday. He also refuses water, though he has been eating his solid baby food well (three meals of 130 g each).

He looked lethargic, vomited slightly once, and cried a lot before falling asleep early at 6:30 PM (he usually sleeps at 7:00 PM). Four hours later, his fever was 38.8°C. I woke him up to give him more medicine, but he resisted again, taking only about 1 ml. He slept well after that, so I didn't wake him again. By 4:00 AM, his temperature was 37.7°C, and by 7:00 AM, it was down to 36.8°C.

Since it was the weekend, we didn't go to the clinic. He is still refusing formula but is currently playing well. Do we need to visit the doctor to find out the cause of the fever, or should we just observe him since he seems fine now?

Answer:

It is a great relief that your 8-month-old's fever has returned to a normal temperature (36.8°C) and that he is playing well. However, his formula intake is quite concerning, as 160 ml in a day is significantly lower than what he needs. It is definitely a positive sign that he is still eating his solid foods well, but hydration remains very important.

Please monitor him closely for signs of dehydration at home. These signs include having fewer than six wet diapers a day, having dry lips or mouth, or an absence of tears when he cries.

You should take him to see a pediatrician immediately if:

• He continues to refuse formula, consuming less than 300 ml total per day.

• He goes 8 hours without a wet diaper, or his urine becomes dark yellow.

• His fever spikes again to 38°C or higher, or he becomes lethargic.

• He experiences rapid breathing or his chest pulls in while breathing (retractions).

For now, since he is refusing the bottle, try offering water or barley tea frequently in small amounts using a spoon. You can also provide extra hydration through cool baby foods or fruit purees.

Additionally, please note that the proper dosage of an acetaminophen-based fever reducer for his weight (9.8 kg) is typically around 3 to 4 ml per dose. Giving only 1 ml is too little to effectively reduce a fever, which is likely why his temperature did not drop significantly when he was hot.

While most temporary fevers like this are caused by simple viral infections, maintaining proper hydration is critical for his recovery. Even though his fever has broken, if his formula intake does not improve shortly, please visit your pediatrician for a thorough evaluation to ensure he is not becoming dehydrated.

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

https://fevercoach.us