RSV symptoms: What to look for if your child has a respiratory virus or the flu

As temperatures begin to drop, a handful of respiratory viruses are spreading at unusually high levels in the U.S. and landing children in the hospital, and doctors are urging parents to be aware of what symptoms signal a serious illness.

Pediatric cases of the flu and RSV, or respiratory syncytial virus, are on the rise. Covid cases are declining in kids, but the coronavirus, too, is circulating at high levels.

Most children should recover on their own from infections of Covid, RSV or the flu, especially with rest and plenty of fluids, said Dr. Paul Offit, a pediatrician and vaccine expert at Children’s Hospital of Philadelphia. But some, including very young children and those with underlying lung issues, may need additional care.

Here are the signs and symptoms to look out for if your child has a respiratory virus.

Does my child have RSV, Covid or the flu?

Because each virus typically begins as an upper respiratory infection, it can be difficult — if not impossible — for parents to know which one they are dealing with early on, said Dr. Kristin Moffitt, an infectious disease specialist at Boston Children’s Hospital. Even for doctors, the only way to determine which virus is causing an infection is by using a test.

Early symptoms of Covid, RSV and the flu can look similar for many children, including:

• Congestion

• Cough

• Runny nose

• Muscle aches

• Fever

• Headache

Less common symptoms include:

• Stomach ache

• Vomiting

• Diarrhea

A sore throat, Moffitt said, could be a sign of Covid, as doctors have noticed that infections with omicron subvariants often begin with sore throats.

At-home Covid tests can help parents determine whether Covid is the cause of their child's illness, although negative test results on rapid tests don't always mean a person is in the clear.

Children can also be tested for RSV or the flu at the doctor’s office, usually with what's called a multiplex test, Moffitt said.

It’s also possible, she said, for a child to be infected with more than one virus at the same time, known as having a coinfection.

Why are respiratory viruses dangerous for very young children?

It all comes down to anatomy: Babies and toddlers have much smaller airways than older children and adolescents. That means that when they get sick with respiratory viruses, their airways can fill up with mucus quickly, leading to breathing problems, said Dr. Deanna Behrens, a pediatric critical care physician at Advocate Children’s Hospital in Chicago.

Children with underlying health conditions, such as chronic lung disease or heart problems, may also be at higher risk for severe illness from respiratory viruses, said Dr. Nusheen Ameenuddin, a pediatrician at the Mayo Clinic in Rochester, Minnesota.

Moffitt said that if parents are unsure whether their children need more help recovering from infections, they should call their pediatricians.

"Pediatricians' offices are very responsive right now trying to alleviate the squeeze that urgent care and pediatric emergency department settings are feeling," she said. They often "open sick slots and things like that to be able to assess children who are not improving and whose parents are concerned but don't quite meet the criteria for an emergency department evaluation."

When should a child go to the emergency room?

Symptoms that warrant an immediate trip to the emergency room include a child's refusing to eat, having difficulty urinating or breathing abnormally, Behrens said.

That is especially important, she said, for "infants and maybe even the toddlers who can’t tell parents what is wrong with them."

Abnormal breathing can be exhibited as rapid breaths, loud wheezing or a struggle to draw in air, Behrens said.

Breathing problems can also manifest as the lips turning blue or the muscles between the ribs pulling inward on each breath, said Ameenuddin, of the Mayo Clinic.

Parents should also seek emergency help if their child has had a fever for more than 4 days, said Dr. Sunitha Kaiser, a pediatrician at UCSF Benioff Children's Hospitals in San Francisco.

If left untreated, severe cases of Covid, RSV or the flu can develop into pneumonia, an infection of the lungs, said Dr. Peter Hotez, a co-director of the Center for Vaccine Development at Texas Children’s Hospital.

RSV, Hotez said, is also known to cause bronchiolitis, an inflammation of the small airways in the lungs. Both conditions can be deadly, especially in children with underlying health conditions.

Is there a treatment for RSV?

A child who is sick with Covid may be given steroids or the antiviral drug remdesivir, Moffitt said. Likewise, a handful of antivirals might be given for the flu, including Tamiflu.

There isn't a treatment for RSV, however, so a child who becomes infected with the virus and is sick enough to go to the hospital is usually offered only supportive care, which can include being put on oxygen, Moffitt said.

There is also no vaccine for RSV, Hotez said. A handful are in development, one of them from Pfizer.

And certain kids with underlying health conditions may be eligible for monoclonal antibody injections to prevent severe RSV.

Hotez also urged parents to get their children vaccinated against Covid and the flu.

"There are three viruses circulating," he said, "and if you can take one or two of them off the table by getting your child vaccinated, that makes things much more straightforward."

Ameenuddin said parents can protect their children who are too young to get vaccinated by creating a “cocoon" in which everyone around the children is vaccinated, decreasing the likelihood of transmission and severe disease.

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This article was originally published on NBCNews.com