What Are the Worst Days of RSV? Symptoms and Timeline

Respiratory Syncytial Virus, commonly known as RSV, is a widespread respiratory virus that infects the lungs and airways. While it often causes mild, cold-like symptoms, RSV can lead to more serious illness, particularly in infants and older adults. Understanding the typical progression of an RSV infection and recognizing signs of increased severity can help in managing the illness.

Typical Course of RSV Infection

Symptoms of an RSV infection appear around four to six days after exposure to the virus. Initial signs resemble a common cold, including a runny nose, sneezing, and a cough. A low-grade fever can also be present, along with a sore throat or headache.

The illness lasts for one to two weeks. While recovery typically occurs within this timeframe, a lingering cough might persist for a longer period, sometimes up to four to eight weeks. For some, the infection can extend into the lower respiratory tract, potentially leading to conditions like bronchiolitis or pneumonia.

Identifying the Most Severe Days

RSV symptoms are most pronounced between days three and five after illness onset. During this peak period, the infection may move beyond typical cold symptoms to affect the lower respiratory tract. This can result in increased breathing difficulty.

Indicators of more severe RSV include wheezing, a high-pitched sound, particularly when breathing out. Rapid, shallow breathing or struggling to breathe, where the chest muscles and skin pull inward with each breath (retractions), can also occur. Nostrils might flare with each breath, indicating increased effort. In infants, severe coughing fits, unusual tiredness, irritability, or poor feeding can signal a worsening condition.

When Emergency Care is Needed

Certain signs indicate immediate medical attention for RSV symptoms. Severe difficulty breathing, such as gasping, choking, or an inability to speak, requires attention. The skin, particularly around the lips or fingernails, can develop a bluish or grayish tint due to a lack of oxygen.

Other red flags include very rapid breathing, pauses in breathing, or a significant decrease in activity and alertness. Signs of dehydration, such as very few wet diapers in infants or an absence of tears when crying, also require prompt evaluation. If symptoms worsen after an initial period of improvement, or if a high fever is present, especially in very young infants, seeking emergency care is appropriate.

Individuals at Higher Risk

Some populations face an increased likelihood of developing severe RSV and complications. Premature infants, especially those born before their lungs and immune systems are fully developed, are at a higher risk. Infants younger than six months are also vulnerable to severe illness.

Children with underlying health conditions, such as chronic lung disease, congenital heart disease, or weakened immune systems, are more susceptible. Older adults, particularly those aged 65 and above, or individuals with pre-existing heart or lung conditions, also have an elevated risk for severe RSV.