Fever and poor feeding in babies: what should you check for with RSV infection?

Hello. I am Shunichi Gamo, MD, PhD, a board-certified pulmonologist and the director of Sendai International Airport North Clinic.

When your baby has a fever and is also drinking less breast milk or formula, the worries pile up. Is it RSV (respiratory syncytial virus, a major cause of colds and bronchiolitis in babies and young children)? Is your baby having trouble breathing?

This article explains what to watch for in your baby’s breathing and feeding, what to do when your baby cannot drink, and what to tell the doctor at the visit. It also covers how testing and treatment are approached, other illnesses that can develop alongside RSV when a fever lasts, and which babies are more likely to become seriously ill.

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Are fever and poor feeding in babies symptoms of RSV infection?

In RSV infection, fever and feeding problems (changes in how a baby drinks breast milk or formula) are commonly reported in children aged 5 and under. [1] However, these two signs alone are not enough to say a child has RSV.

One systematic review (a report that brings together and examines many studies) looked at children aged 5 and under. Across 25 studies, a runny or stuffy nose, cough, difficulty breathing, problems with feeding or eating, and fever were each reported in 40% or more of children. [1]

On the other hand, RSV infection can also appear as inflammation of the nose and throat with little or no fever. [2] A low fever does not rule out RSV infection.

Symptom	What was reported in children aged 5 and under with RSV
Runny or stuffy nose, cough, difficulty breathing	In 25 studies of children aged 5 and under, these were reported in 40% or more of children. [1]
Problems with feeding or eating, fever	In the same studies of children aged 5 and under, feeding or eating problems and fever were also reported in 40% or more of children. [1]
Nose and throat inflammation with little fever	RSV infection is described as sometimes appearing as inflammation of the nose and throat with little or no fever. [2]

Try to remember what time the fever started and when your baby began drinking less than usual, so you can tell the doctor at the visit.

How does RSV infection usually progress in babies, and what should you look for in their breathing?

RSV bronchiolitis is inflammation of the small airways deep in the lungs. It is described as usually starting with 2 to 4 days of cold-like symptoms such as fever and a runny or stuffy nose, then moving on to more coughing, wheezing and visible effort to breathe. [3] Early symptoms are reported to include a runny nose, stuffy nose, sneezing and fever. [4] A pediatric review article (an overview that brings together several reports) also says that a stuffy nose, runny nose and mild fever appear in the first 1 to 3 days. Symptoms then get worse over several days and settle over days to weeks. [5]

In RSV bronchiolitis, certain signs show that the infection has spread to the airways closer to the lungs (the lower airways). They include cough, fast breathing, retractions (part of the chest sinking in with each breath), difficulty feeding, and use of the extra muscles that help with breathing. [4] Wheezing is described as a lower-airway symptom that follows symptoms such as a runny nose and fever. [3]

What to watch	What the medical sources say	How you might describe it
Breathing rate	Fast breathing is listed as a sign that RSV bronchiolitis has spread to the lower airways. [4]	“My baby keeps breathing fast, even while resting quietly.”
Chest sinking in	Retractions (part of the chest sinking in with each breath) are listed as a sign that RSV bronchiolitis has spread to the lower airways. [4]	“The chest sinks in every time my baby breathes in.”
Wheezing	In RSV bronchiolitis, wheezing is listed as a lower-airway symptom. [3]	Tell the doctor what time the wheezing started
Feeding	Difficulty feeding is listed as a sign that RSV bronchiolitis has spread to the lower airways. [4]	Tell the doctor how the amount per feeding and the number of feedings have changed

While your baby is calm, loosen their clothes and watch how the chest and belly move. This will help you describe their breathing to the doctor in concrete terms.

When your baby is drinking less, what should you tell health care providers about fluids?

When your baby is drinking less, write down how much and how often they drink compared with usual, how often they pee, and any change in mood or responsiveness. Share this with health care providers. Also tell them if your baby starts to look short of breath as soon as they try to drink.

In RSV bronchiolitis, maintaining fluids and nutrition, in addition to maintaining oxygen levels, is considered one of the main parts of treatment. For infants who cannot keep up their fluids by drinking, fluids may be given as needed through a tube passed from the nose into the stomach (a nasogastric tube) or through an IV drip. [3][4]

Health care providers decide whether a tube or an IV drip is needed after examining your baby.

Signs to watch at home	When and how to seek care
Your baby is clearly drinking less, or less often, than usual	Tell health care providers how much the amount and number of feedings have dropped, and contact a medical facility soon.
Your baby is peeing less often	Write down how often your baby pees and how that has changed, tell the doctor, and get advice soon.
Your baby is limp and less responsive	Do not hesitate to seek medical care, even at night.
Your baby looks short of breath when trying to drink	If your baby cannot drink because they look short of breath, see a doctor and describe how they are drinking and breathing.

Does a baby need a test to diagnose RSV infection?

A review article describing the American Academy of Pediatrics guideline says that bronchiolitis is diagnosed mainly from the symptoms and the physical examination. [3] Another review (a rapid evidence review) also does not recommend routine chest X-rays or virus testing. [4]

The approach in the US guideline and the reviews described here may differ by country, including Japan, and by medical facility. Please ask the doctor at the visit whether testing is needed and what it is for.

How is RSV treated?

Treatment of RSV bronchiolitis centers on supportive care (care that supports the body). A rapid evidence review (a literature review put together over a short period) mentions keeping oxygen saturation (the oxygen level in the blood, shown as a percentage) above 90%. It also mentions keeping up fluids and nutrition, through a nasogastric tube or an IV drip if needed. [4] Bronchodilators, epinephrine (adrenaline), inhaled hypertonic saline, steroids and chest physiotherapy are not recommended. [4]

The pediatric review article also lists nasal suction, oxygen (when oxygen levels are low) and fluids as supportive care. Bronchodilators and systemic steroids are not recommended for babies and young children aged 1 to 23 months. [5]

If the fever continues, please see a doctor to check whether another illness, such as an ear infection or pneumonia, has developed as well.

Treatment	Recommendation for babies and young children with RSV bronchiolitis (reviews and guidelines)
Supportive care to maintain oxygen, fluids and nutrition	Supportive care to maintain oxygen, fluids and nutrition is listed (rapid evidence review). [4]
Bronchodilators, systemic steroids (by mouth or injection)	Not recommended for babies and young children aged 1 to 23 months with RSV bronchiolitis (pediatric review article). [5]

Before giving an infant any over-the-counter medicine or medicine you have at home, always ask a doctor or pharmacist. Please do not give medicine based on your own judgment.

When a fever lasts, should you worry about complications of RSV infection?

The most common complication (another illness that develops on top of the original one) of RSV infection is reported to be an acute middle ear infection. [2] If the fever is slow to come down, please see a doctor to check whether an ear infection or pneumonia has developed as well.

Are very young babies and premature babies more likely to get seriously ill with RSV?

In a study of hospitalized children, very young babies and premature babies were linked to a more severe course. Age 3 months or younger, premature birth and apnea (pauses in breathing) were identified as risk factors for a severe course. [6]

However, a study at children’s hospitals in the US pointed out that many children hospitalized for acute respiratory infection caused by RSV had been previously healthy. In the same study, younger age was linked to hospitalization among children who tested positive for RSV. [7] Even if there is nothing worrying in your baby’s background, please see a doctor if there are changes in their feeding or breathing.

Your baby’s background	What to keep in mind when seeking care
Babies aged 3 months or younger	If feeding or breathing seems different from usual, see a doctor soon. Tell the doctor your baby’s age in months.
Babies born prematurely	If feeding or breathing seems different from usual, see a doctor soon. Tell the doctor your baby was born prematurely.
Babies who seemed to stop breathing	If your baby seems to stop breathing, call an ambulance right away.

If feeding or breathing seems different from usual, see a doctor soon. At the visit, tell the doctor if your baby was born prematurely or is very young.

When you take a baby with fever and poor feeding to the doctor, what is helpful to mention?

At the visit, tell the doctor when the symptoms started and how they have changed, how your baby is breathing, how much they are drinking, how often they pee, and how they were born. Diagnosing bronchiolitis mainly from the symptoms and the physical examination is considered the standard approach, so what you have observed provides clues to the diagnosis. [3]

What to mention	Details
How the symptoms have progressed	Write down the time the fever started, the day the runny nose or cough began, and how the fever has changed.
Breathing	Tell the doctor if your baby has been breathing fast, the chest has been sinking in, there has been wheezing, or your baby has seemed to stop breathing.
Feeding and fluids	Tell the doctor how much your baby is drinking compared with usual, how many feedings there have been, and how often they pee.
Your baby’s background	Tell the doctor your baby’s age in months, whether they were born prematurely, and whether they have any ongoing health conditions.
Family and surroundings	Tell the doctor whether anyone in your family or at daycare or preschool has a cough or runny nose.

If your baby seems to be struggling to breathe, is limp and less responsive, or can take almost no fluids, seek medical care, even at night.

Summary

• Fever and drinking less breast milk or formula are common in RSV infection. But the fever may not stand out, and symptoms alone cannot confirm RSV.
• Besides fast breathing, the chest sinking in and wheezing, changes in feeding (difficulty feeding) are also worth checking and telling health care providers about.
• Treatment centers on supporting fluids, nutrition and oxygen.
• In a study of hospitalized children, very young babies and premature babies were linked to a more severe course.
• If your baby cannot take fluids, seems to be struggling to breathe, or is limp, seek medical care, even at night.

Frequently asked questions

Can my baby have RSV infection even without a fever?

Yes. RSV infection is described as sometimes appearing as inflammation of the nose and throat with little or no fever. [2] Even without a fever, if your baby is breathing fast or drinking less, please see a doctor.

Does every baby need a test to check for RSV infection?

No, not always. A review article describing the US guideline says that bronchiolitis is diagnosed from the symptoms and the examination, and that tests for diagnosis are not routinely recommended. [3] The doctor will decide at the visit whether a test is needed, so please see a doctor if you notice worrying symptoms.

If my baby cannot drink, might they need an IV drip or a tube?

Yes, sometimes. For infants who cannot keep up their fluids by drinking, fluids may be given through a tube passed from the nose into the stomach or through an IV drip. [3] Health care providers decide at the visit whether this is needed, so see a doctor if your baby is clearly drinking less than usual.

Should I be especially careful if my baby was born prematurely?

In a study of hospitalized children, premature birth was linked to needing oxygen and to respiratory failure. [6] Always tell the doctor at the visit that your baby was born prematurely.

Disclaimer

This article provides general medical information. It does not replace an examination, diagnosis or treatment by a doctor. The content is based on medical knowledge at the time of publication, but the right approach differs with each patient’s condition and background.

If you are worried about your symptoms, please talk to your regular doctor or a specialist medical facility.

References

1. Colosia A, Costello J, McQuarrie K, Kato K, Bertzos K. “Systematic literature review of the signs and symptoms of respiratory syncytial virus.” Influenza Other Respir Viruses, 2023 Feb; 17(2): e13100. DOI: 10.1111/irv.13100 PMID: 36824394
2. Casalegno JS. “[RSV and associated diseases].” Rev Prat, 2022 Oct; 72(8): S5-S7. PMID: 36512000
3. Smith DK, Seales S, Budzik C. “Respiratory Syncytial Virus Bronchiolitis in Children.” Am Fam Physician, 2017 Jan 15; 95(2): 94-99. PMID: 28084708
4. Oppenlander KE, Chung AA, Clabaugh D. “Respiratory Syncytial Virus Bronchiolitis: Rapid Evidence Review.” Am Fam Physician, 2023 Jul; 108(1): 52-57. PMID: 37440737
5. Lowe MC. “Childhood Respiratory Conditions: Lower Respiratory Tract Infection.” FP Essent, 2022 Feb; 513: 20-24. PMID: 35143151
6. Kobiałka M, Jackowska T, Wrotek A. “Risk Factors for Severe Respiratory Syncytial Virus Infection in Hospitalized Children.” Viruses, 2023 Aug 09; 15(8): 1713. DOI: 10.3390/v15081713 PMID: 37632055
7. Haddadin Z, Beveridge S, Fernandez K, Rankin DA, Probst V, Spieker AJ, et al. “Respiratory Syncytial Virus Disease Severity in Young Children.” Clin Infect Dis, 2021 Dec 06; 73(11): e4384-e4391. DOI: 10.1093/cid/ciaa1612 PMID: 33095882