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Respiratory syncytial virus

Medically reviewed by Last updated on Mar 18, 2024.

What is respiratory syncytial virus?

Harvard Health Publishing

Respiratory syncytial virus (RSV) is one of the many viruses that cause the common cold and infections in the upper parts of the respiratory tract. RSV also can cause infection in the lower respiratory tract, such as pneumonia in the lung tissue and bronchiolitis inside the smallest airways (bronchioles) in the lungs.

RSV is spread in secretions when someone with it coughs or sneezes. RSV also can be carried on unwashed hands and on contaminated objects such as dirty tissues, doorknobs, and desk tops. It typically enters the body through the eyes, nose, or mouth when someone with contaminated fingers touches his or her face or eyes or breathes in droplets.

People who have the greatest risk of serious illness from RSV include:

The highest rates of serious childhood RSV illness occur in infants under 8 months old. Almost all children have been exposed to RSV by the age of 2. Most do not become dangerously ill. Getting RSV more than once can happen, but infections that follow the first one generally are mild.

Symptoms of RSV

RSV tends to cause typical cold symptoms, including:

In general, the symptoms caused by RSV tend to be more severe than the average common cold. Symptoms generally begin within a week after an exposure to someone with an RSV infection.

In infants and children younger than age 3, or older children with underlying lung, heart, or immune problems, RSV may start out looking like a mild cold with sneezing and runny nose. After two or three days, RSV can spread into the chest, causing a cough, breathing that is faster than normal, and wheezing. Babies who were born prematurely, or those with lung problems, congenital heart disease, or problems with their immune systems, have a higher chance of getting a serious RSV infection.

Young children also can have a high fever. Infants with breathing difficulties may grunt, flare the nostrils, or have "retractions," which means the chest muscles are drawn in so that the ribs can be seen as the baby struggles to breathe.

Diagnosing RSV

Your doctor may suspect an RSV infection based on the symptoms and a physical examination during certain times of the year when RSV is most common. In most adults and older children, further testing is unnecessary because RSV symptoms generally are mild, and the illness usually is treated at home.

When examining infants and children younger than age 3, or children with underlying lung, heart, or immune problems, the doctor will check for fever, cough, nasal discharge that may interfere with feeding, the chest drawing in, wheezing, breathing quickly, and a bluish color to the lips and fingernails. If your child's symptoms are severe or not as expected, the doctor may want to confirm the diagnosis of RSV infection by taking a sample of nose or throat secretions to test for the virus in a laboratory.

Expected duration of RSV

In people who are basically healthy, RSV infection typically lasts about one to two weeks. However, the wheezing that is caused by RSV can last a month or longer.

Preventing RSV

Preventing RSV is difficult because the virus is highly contagious and is spread easily from person to person. The best way to prevent RSV infection is to wash hands regularly, especially when someone in the family has cold symptoms. Adults and older children should always wash their hands frequently, avoid touching their face and eyes unnecessarily, and stay away from direct contact with people who have obvious cold symptoms. Young infants should be kept away from anyone who has symptoms of a respiratory infection, even if it's just a slight cold.

The American Academy of Pediatrics and United States Centers for Disease Control and Prevention recommends that infants less than 8 months old receive one dose of nirsevimab during the peak RSV season, unless the mother received RSV vaccination. Infants older than 8 months who are at risk of severe infection may be offered a second dose. Nirsevimab is a monoclonal antibody given by injection.

Vaccination against RSV is available for adults 60 years and older. The vaccine helps prevent severe symptoms and hospitalization secondary to RSV pneumonia. Older adults with significant heart or lung disease or who have compromised immune systems will benefit most from the vaccine.

Treatment options

The following list of medications are related to or used in the treatment of this condition.

View more treatment options

Treating RSV

For mild RSV infections, treatment is aimed at making the person comfortable. Treatment may include:

Infants and younger children with severe RSV infection may need to be hospitalized. In the hospital, the infant or child may receive oxygen, fluids (by vein), and medications to help him or her breathe easier. Certain patients with weakened immune systems may be given a medication called ribavirin.

When to call a professional

Call your doctor immediately if your infant or younger child has:

If you have a premature infant or one with serious respiratory or other health problems, speak to your doctor about your baby's need for preventive medicines from late fall through early spring.


Most RSV infections go away completely with no lasting effects. With prompt diagnosis and appropriate treatment, most infants and children recover from serious respiratory illnesses caused by RSV infections. Deaths from RSV infections are relatively rare, but RSV infection can cause death in high-risk infants ages 2 months to 8 months, and in older infants and older adults with certain chronic diseases or who have immune system problems.

Children who have RSV bronchiolitis in infancy have a slightly higher risk of having recurrent wheezing as they get older. It's not known if RSV causes this, or whether children who are at higher risk of asthma are more likely to become ill with RSV exposure during infancy.

Additional info

Centers for Disease Control and Prevention (CDC) 

Learn more about Respiratory syncytial virus

Treatment options

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.