RSV (respiratory syncytial virus): symptoms, causes, treatment, prevention and when to worry

Respiratory syncytial virus, better known as RSV, is a common virus that infects the respiratory tract, including the nose, throat and lungs. For many healthy children and adults, RSV causes a mild illness that resembles a common cold. However, the same infection can become serious in young infants, older adults and people with certain underlying health conditions.

RSV is particularly important in babies because infection can progress from a runny nose and cough to bronchiolitis or pneumonia, sometimes requiring hospital care. Nearly all children encounter RSV by the age of two, and reinfection can occur throughout life.

Understanding the early symptoms, knowing how RSV spreads and recognising warning signs can help you seek medical care at the right time.

What is RSV?

RSV stands for respiratory syncytial virus. It is an RNA virus that infects cells lining the respiratory tract. RSV belongs to the Pneumoviridae family and occurs in two major subgroups, RSV-A and RSV-B.

RSV is a virus, not a bacterium, so antibiotics do not treat the RSV infection itself.

Most infections affect the upper respiratory tract and cause symptoms similar to a cold. In some people, particularly vulnerable infants and older adults, the infection can move into the lower airways and lungs.

RSV can cause:

• Bronchiolitis
• Pneumonia
• Wheezing
• Difficulty breathing
• Low oxygen levels
• Dehydration due to poor feeding or drinking

Most infections are mild, but severe RSV disease can require hospitalisation.

What is the main cause of RSV?

The cause of RSV infection is exposure to the respiratory syncytial virus.

RSV spreads readily from an infected person through respiratory particles and direct contact. You can become infected when an infected person coughs or sneezes near you, or when respiratory secretions reach your eyes, nose or mouth. The virus can also spread through contaminated surfaces and objects.

This is one reason RSV can spread quickly among families, schools, childcare settings and other places where people are in close contact.

How is RSV transmitted?

RSV can spread in several ways:

• Coughing and sneezing
• Close face-to-face contact
• Kissing
• Touching contaminated surfaces
• Touching your nose, mouth or eyes after contact with the virus

For example, kissing babies can spread RSV if the person kissing the baby is infected. CDC specifically identifies kissing the face of a child with RSV as a form of direct contact through which the virus can spread.

Good hand hygiene, avoiding close contact when sick and improving indoor ventilation can reduce the risk of transmission.

What are the first signs of RSV?

The very first signs of RSV can be easy to mistake for an ordinary cold.

Symptoms generally begin about 4–6 days after infection, although the timing can vary.

Early symptoms may include:

• Runny nose
• Stuffy or congested nose
• Sneezing
• Reduced appetite
• Mild cough
• Fever
• Fatigue
• Sore throat in older children and adults

In babies, the earliest symptoms may be less obvious. A baby may simply become unusually irritable, less active or feed less than usual. Very young infants may develop breathing difficulties or pauses in breathing.

What are the very first signs of RSV in babies?

In babies, look for:

• Irritability or unusual fussiness
• Reduced activity
• Eating or drinking less
• Runny nose
• Cough
• Changes in breathing

A particularly important point is that very young babies may not always have a fever even when they have RSV.

Because symptoms can become more severe several days after the infection begins, parents should pay attention to changes in breathing and feeding rather than looking only for fever.

RSV symptoms by age

RSV does not look exactly the same in everyone.

Symptoms in babies

Babies may develop:

• Irritability
• Poor feeding
• Runny nose
• Cough
• Reduced activity
• Wheezing
• Rapid or difficult breathing
• Pauses in breathing

In severe cases, the chest may pull inward with each breath, and the baby may struggle to breathe.

Symptoms in toddlers and children

Older children may experience:

• Runny nose
• Congestion
• Cough
• Sneezing
• Fever
• Reduced appetite
• Wheezing
• Breathing difficulty

Some children develop bronchiolitis or pneumonia when the infection reaches the lower respiratory tract.

Symptoms in adults

Adults generally experience a cold-like illness, including:

• Runny or blocked nose
• Sore throat
• Cough
• Headache
• Fatigue
• Fever
• Wheezing

Healthy adults often recover without complications. However, RSV can be more serious in older adults and those with chronic heart or lung disease.

Is RSV a serious illness?

RSV can be serious, but it is not serious for everyone.

For most healthy older children and adults, RSV causes a mild illness that gets better with supportive care. The risk changes considerably depending on age and overall health.

Severe RSV disease is more likely in:

• Young infants, particularly those under 6 months
• Premature babies
• Children with chronic lung disease
• Children with congenital heart disease
• People with weakened immune systems
• Older adults
• Adults with chronic heart or lung disease

WHO estimates that RSV causes millions of lower respiratory tract infections and millions of hospitalisations among children under five worldwide each year.

What age is scariest for RSV?

There isn’t one single age at which RSV is always dangerous, but very young infants are among those at greatest risk of severe disease.

The younger the infant, the less developed the airways and immune system are. Babies under six months, particularly premature infants and those with underlying medical conditions, deserve close attention.

Older adults are another important high-risk group, especially those with heart or lung disease or weakened immunity.

Who is most at risk for RSV?

Anyone can get RSV, but severe disease is more likely in certain groups.

Babies and young children

Risk is higher in:

• Premature infants
• Infants under six months
• Children with chronic lung disease
• Children with congenital heart disease
• Children with neuromuscular disorders
• Children with weakened immunity

Adults

Higher-risk adults include:

• Older adults, particularly those 75 and above
• Adults with chronic heart disease
• Adults with chronic lung disease such as COPD
• People with weakened immune systems
• People living in nursing homes or long-term care settings

RSV can also trigger worsening of existing asthma, COPD or heart failure.

What happens when adults get RSV?

In most healthy adults, RSV resembles a common cold and gets better within one to two weeks.

However, older or medically vulnerable adults can develop more serious disease. RSV may progress to pneumonia or worsen existing conditions such as asthma, COPD or heart failure. Severe cases may require hospitalisation.

Adults should seek medical advice if symptoms are getting worse rather than better, particularly if breathing becomes difficult or there is chest pain, dizziness, confusion or difficulty maintaining fluid intake.

Is RSV worse than COVID?

There is no universal answer to whether RSV is worse than COVID-19.

RSV and COVID-19 are caused by different viruses and can affect people differently. Both can cause mild respiratory illness in many people and severe disease in people at higher risk.

RSV is particularly important in infants and can cause bronchiolitis and pneumonia. COVID-19 can also cause severe respiratory disease and other complications, particularly in vulnerable people.

Because symptoms overlap, symptoms alone cannot reliably tell you whether you have RSV, COVID-19, influenza or another respiratory infection. Testing can help distinguish some of these infections.

Is RSV a form of COVID?

No. RSV is not a form of COVID-19.

RSV is caused by respiratory syncytial virus, while COVID-19 is caused by SARS-CoV-2. They belong to different virus families.

They can, however, produce similar symptoms such as cough, fever, fatigue and breathing problems. It is also possible for respiratory viruses to circulate at the same time, which can make diagnosis based on symptoms alone difficult.

Is RSV as bad as pneumonia?

RSV and pneumonia are not directly comparable because they describe different things.

RSV is a virus. Pneumonia is an infection or inflammation of the lungs that can be caused by viruses, bacteria and other organisms.

RSV can cause pneumonia as a complication. It can also cause bronchiolitis, particularly in babies.

So, having RSV does not automatically mean you have pneumonia. However, if an RSV infection progresses into the lungs, the illness can become serious.

How is RSV diagnosed?

A healthcare professional may diagnose RSV based on symptoms and the person’s age and risk factors. When confirmation is needed, laboratory testing can detect RSV.

Common tests include:

• PCR or other nucleic acid amplification tests (NAATs): highly sensitive
• Antigen tests: generally faster but less sensitive than molecular tests

Testing may be particularly useful when distinguishing RSV from influenza, COVID-19 or other respiratory infections could affect treatment or infection-control decisions.

What is the best treatment for RSV?

There is currently no routinely recommended specific antiviral treatment for uncomplicated RSV. Treatment generally focuses on relieving symptoms and supporting the body while it recovers.

Depending on the person’s age and condition, supportive care may include:

• Adequate fluids
• Rest
• Fever and pain relief when appropriate
• Nasal saline and gentle suction for babies with congestion
• Monitoring breathing
• Medical treatment for complications or worsening underlying conditions

Severe cases may require hospital treatment, including oxygen and fluids.

How to treat adult RSV at home

For a healthy adult with mild RSV, home care usually focuses on comfort and hydration.

You can:

• Get adequate rest.
• Drink plenty of fluids.
• Use appropriate fever or pain medicine if needed and medically suitable.
• Keep the air comfortable and avoid cigarette smoke.
• Consider saline nasal rinses or sprays for congestion.
• Avoid close contact with vulnerable people while you are sick.
• Monitor symptoms rather than assuming every cough is harmless.

If you have heart disease, lung disease, a weakened immune system or are an older adult, speak with a healthcare professional earlier if symptoms develop.

Do you need antibiotics if you have RSV?

Usually, no.

RSV is a viral infection, and antibiotics do not kill viruses. Taking antibiotics unnecessarily will not make RSV disappear faster and can expose you to medication side effects and contribute to antibiotic resistance.

An antibiotic may be prescribed if a healthcare professional identifies a separate bacterial infection, such as a bacterial complication.

Do not start leftover antibiotics or take someone else’s prescription simply because you have a persistent cough.

How long does RSV last?

For many people, RSV symptoms improve within one to two weeks.

The duration can vary depending on age, immune status and whether complications develop.

A cough or tiredness can sometimes persist after the main symptoms have improved. In high-risk individuals, the illness may become more serious before recovery begins.

If symptoms initially improve and then suddenly worsen, medical evaluation is advisable.

Is RSV worse at night?

RSV itself does not necessarily become biologically more severe at night. However, coughing and congestion can feel worse when lying down, particularly at night.

Nasal congestion can make breathing and feeding more difficult for babies, while coughing may interfere with sleep in children and adults.

For infants, difficulty breathing, pauses in breathing, poor feeding or a change in skin colour should never be dismissed as simply “night-time RSV.”

Do I need to isolate if I have RSV?

If you have RSV symptoms, it is sensible to stay home and away from others while you are sick, particularly from babies, older adults and people at higher risk of severe respiratory illness.

Current CDC respiratory-virus guidance recommends returning to normal activities when, for at least 24 hours, your symptoms are improving overall and you have been free of fever without using fever-reducing medication. After returning to normal activities, additional precautions such as better ventilation, hygiene, masking and distancing are recommended for the next five days.

The exact precautions may need to be adapted to your household, workplace or healthcare setting.

How can I prevent RSV?

Several everyday measures can reduce the spread of RSV.

Practise good hand hygiene

Wash your hands regularly with soap and water or use an alcohol-based hand sanitiser when appropriate.

Avoid close contact when sick

Don’t kiss babies or share close face-to-face contact with others when you have a respiratory infection.

Clean frequently touched surfaces

Regularly clean objects and surfaces that are frequently handled, particularly in households with young children.

Improve indoor air

Ventilation and cleaner indoor air can reduce exposure to respiratory viruses.

Consider immunisation where appropriate

RSV immunisation options are now available for certain infants, pregnant people and older or higher-risk adults, depending on the recommendations and products available in the country. Eligibility and schedules vary, so discuss RSV prevention with your doctor.

Is RSV risky?

RSV can be risky, but the level of risk varies greatly.

A healthy adult may experience nothing more than a cold-like illness. A premature infant, very young baby, older adult or person with significant heart or lung disease may develop severe respiratory disease.

The most important question is therefore not simply “Is RSV dangerous?”, but “Who has RSV, and what risk factors do they have?”

When should you seek medical help?

Seek urgent medical attention if you or your child develops:

• Difficulty breathing
• Rapid or laboured breathing
• Blue or grey lips, face or skin
• Chest pulling inward during breathing
• Significant dehydration or inability to drink
• Pauses in breathing in a baby
• Severe weakness or unusual sleepiness
• Chest pain or pressure
• Confusion or sudden dizziness
• Symptoms that are getting significantly worse

In babies, poor feeding combined with breathing difficulties deserves particular attention. Severe RSV can progress quickly in vulnerable infants.

What is the fastest way to recover from RSV?

There is no guaranteed shortcut that makes RSV disappear immediately. The fastest route to recovery is generally supportive care, adequate hydration, rest and appropriate symptom management, while watching for complications.

Avoid unnecessary antibiotics or unproven treatments. If you are in a high-risk group, seek medical advice promptly rather than waiting for symptoms to become severe.

Most uncomplicated RSV infections improve naturally within one to two weeks.

Frequently asked questions about RSV

Can kissing babies spread RSV?

Yes. Kissing a baby’s face can spread RSV if the person is infected. Because very young infants are among those at greatest risk of severe disease, people with respiratory symptoms should avoid close contact with babies.

Is RSV worse than COVID?

Neither infection is universally “worse.” Severity varies according to age, underlying conditions and the individual infection. RSV is particularly significant in young infants, while COVID-19 can also cause severe illness in vulnerable people.

Is RSV a virus or bacteria?

RSV is a virus, specifically an RNA respiratory virus. Antibiotics do not treat RSV.

Can RSV turn into pneumonia?

Yes. RSV can cause pneumonia, particularly in infants, older adults and people with underlying health conditions.

Can adults get RSV more than once?

Yes. Immunity after infection is not lifelong, so people can become infected with RSV again. Subsequent infections are often milder, although older adults and people with underlying conditions can still become seriously ill.

How long is RSV contagious?

People are generally most contagious during the early part of illness, but the duration can vary. Infants and people with weakened immune systems may remain able to spread the virus for longer.

Should I get tested for RSV?

Testing may be useful when the result could affect medical care, infection-control decisions or the evaluation of a high-risk patient. PCR/NAAT tests and antigen tests are available.

Does RSV always cause fever?

No. Fever is common but isn’t present in everyone, particularly some very young infants.

Can RSV cause wheezing?

Yes. Wheezing can occur when RSV affects the lower respiratory tract. It is particularly important when accompanied by rapid or difficult breathing.

Final thoughts

RSV is common, highly transmissible and usually mild in healthy people, but it should not be underestimated in young infants, older adults and people with underlying heart, lung or immune problems.

The earliest symptoms can look like an ordinary cold: a runny nose, congestion, cough, reduced appetite or fatigue. The key is to watch how the illness progresses. Increasing breathing difficulty, poor feeding, dehydration, unusual sleepiness, chest retractions or pauses in breathing are warning signs that require prompt medical attention.

Good hand hygiene, avoiding close contact while sick, cleaner indoor air and appropriate RSV immunisation for eligible groups can all help reduce the risk of severe disease and transmission.

Important: This article is intended for general health education and does not replace an examination or advice from a qualified healthcare professional. Babies with breathing difficulties, poor feeding or pauses in breathing should be assessed urgently.

To consult a Doctor at Sparsh Diagnostic Centre, call our helpline number 9830117733.

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