Cold vs. Flu vs. RSV in Children: How To Tell the Difference
Does your child have a cough, runny nose or congestion, a fever, and is generally feeling unwell? They likely have a virus that causes the common cold, influenza, or RSV. These are common childhood illnesses that are usually resolved with fluids, rest, and time.
But what is the difference between these common childhood illnesses? And when should you be worried? Additionally, when should you contact your child’s pediatrician or even take them to the emergency room?
Today we’ll explain the differences and similarities between the common cold, influenza (flu), and RSV in children. We’ll help you recognize common symptom patterns, understand why these illnesses can be difficult to distinguish, and know when symptoms warrant contacting your child’s pediatrician.
If you do need help, contact Nevada Pediatric Specialists. We offer sick visits, a walk-in clinic for non-emergency issues that can’t wait for regularly scheduled appointments, and telemedicine for when you can’t make it into our office.
What Is the Difference Between RSV, Flu, and a Cold in Children?
The common cold, the flu (officially influenza), and RSV (or respiratory syncytial virus) are all common illnesses that anyone can acquire but may affect children differently.
These illnesses are caused by viruses, which are unaffected by antibiotics. There is no pill your child can take to combat these diseases directly. Fortunately, with time, rest, and fluids, your children’s immune system will generally fight them off on their own.
In general, all these illnesses affect the respiratory system, but all have slightly different presentation patterns in the body. However, there is significant overlap between symptoms, and they can’t always effectively be diagnosed at home.
The Common Cold
The common cold is generally caused by the rhinovirus, although there are some other viruses that can cause cold-like symptoms. Symptoms include a cough, runny or stuffy nose, sneezing, and occasionally a mild fever, all often presenting slowly.
Symptoms generally start getting better within a few days and begin disappearing within a week or so.
Influenza
Influenza is caused by the influenza virus. In contrast to the common cold, symptoms generally come on suddenly. Symptoms include fever (including high fever), body aches, headaches, cough, and congestion. Vomiting and diarrhea are also possible.
In general, flu symptoms are more intense than a cold. Starting at 6 months of age, your child can get a flu vaccination, which will help them fight any instances of the disease.
RSV
RSV is caused by the respiratory syncytial virus, and has symptoms similar to the common cold: cough, runny or stuffy nose, sneezing, etc. However, RSV has a greater cause of causing complications, such as bronchitis or pneumonia, especially in children.
How Can I Tell If My Child Has RSV Symptoms vs. a Cold?
RSV often begins like a cold. It may begin with a runny nose and a cough, for example, but a cold generally stays in the upper respiratory tract (the face, mouth, and throat) and rarely progresses deeply into the lungs.
However, RSV often progresses into the lungs and may include a deep cough. While RSV can begin mildly like a cold, it may get noticeably worse after a few days instead of getting better.
Since there is significant overlap between the two illnesses, they often cannot be accurately diagnosed at home. If you suspect your child may have RSV, or their symptoms do not improve within a couple of days or get worse, contact Nevada Pediatric Specialists for further advice.
What Are the Differences Between RSV vs. Flu Symptoms?
The flu often presents suddenly and often leaves children feeling generally awful and exhausted with significant body aches. In many cases, it comes with a fever and often can include vomiting or diarrhea. Children generally start to feel better within a few days.
RSV often begins more mildly, like a cold, but can progress and get worse as time passes. It is less likely to have issues such as body aches, vomiting, or diarrhea.
Again, caution should be warranted in attempting to diagnose either of these illness at home by symptoms alone, and if your child’s condition does not improve within a few days, contact your pediatrician.
Are RSV Symptoms Different in Babies and Older Children?
Yes, RSV symptoms are often different in babies and older children. Babies may experience difficulty eating, have fewer wet diapers, show decreased activity, and, in severe cases, difficulty or rapid breathing.
Since babies are more delicate and can become dehydrated more quickly than older children, changes in feeding, toileting, or breathing should be taken seriously.
Contact us promptly if your child develops breathing issues, especially if they are younger than 6 months old.
When Should I Call My Child’s Pediatrician for Respiratory Symptoms?
You should contact us if your child’s symptoms are concerning, are unusually severe, last an unusually long time, or are getting worse over time, rather than improving. When in doubt, it’s best to contact us or visit us for a walk-in appointment.
Concerning symptoms include the following:
- A high fever that lasts for several days or returns after improving
- Breathing difficulty or wheezing
- A cough that doesn’t improve
- Signs of dehydration
- In babies, difficulty feeding
- Symptoms that do not improve or get worse
Emergency symptoms include any difficulty breathing or signs your child is getting a lack of oxygen, such as blue lips or fingernails, breathing pauses, and unresponsiveness. In addition, if your child experiences a seizure, you should also seek immediate medical attention by visiting an ER or by calling 911.
Call Nevada Pediatric Specialists
If your child is experiencing any concerning symptoms, call Nevada Pediatric Specialists today for an appointment, or visit our walk-in clinic in Henderson or Las Vegas.
Sources:
Foley, D., et al. (2025). RSV: An Update on Prevention and Management.
Respiratory syncytial virus. (2026).