Seasonal illnesses like flu and RSV (respiratory syncytial virus) often arrive when the weather turns cool. At MU Health Care, our experts can diagnose, treat and help you recover from seasonal viruses or infections. For prevention, we offer vaccinations in our primary care and Quick Care clinics.

Seasonal illnesses are common, but they sometimes turn serious in people who have compromised or developing immune systems. Infants and children born prematurely are at a greater risk of severe illness, as are people with preexisting heart or lung conditions, such as asthma, and older adults.

Our doctors have experience in caring for people who are sick with infectious diseases, both in primary care settings and with teams dedicated to adults and children specifically.

Seasonal Illness guide

Seasonal illnesses, many of which are viruses, are contagious and spread in day cares, schools, at work and in public spaces. If you feel sick, or if someone in your family is sick, doctors recommend staying at home until you feel better whenever possible. Washing your hands, covering coughs and sneezes and disinfecting surfaces can help stop seasonal illnesses from spreading.

Diagnosis is an important part of understanding care and recovery, especially if you or someone in your family is at a high risk of severe illness. The very young, very old and those with preexisting heart or lung conditions should closely monitor their symptoms.

If you develop new symptoms, or if symptoms worsen, you should seek medical attention, such as MU Health Care’s primary care or Quick Care clinics. Come to the emergency department if you need help urgently, or if you need help outside of clinic hours.

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Colds are very common infections of the nose, throat or ears. They are contagious and spread from close contact with someone who is sick.

Symptoms include:

  • Mild fever
  • Mild cough
  • Runny nose
  • Sore throat
  • Sneezing

You may also feel chills or aches. These symptoms may last a few weeks and usually improve at home with rest and over-the-counter medication: cough drops, antihistamines, decongestants.


Influenza, or flu, is a common respiratory tract (mouth to lungs) infection. It is contagious and spreads from close contact with people who are sick.

Flu can cause symptoms including:

  • Dehydration
  • Fatigue
  • Headaches
  • Chills
  • Fever
  • Sneezing and coughing
  • Vomiting or diarrhea in some cases

Most people start to feel better after five days, though you may cough or feel tired for a week after other symptoms have cleared.

In some cases, flu infection can cause serious complications that require hospitalization. The best way to guard against serious illness from the flu, which mutates every year to overcome human immune systems, is by getting vaccinated.


RSV (respiratory syncytial virus) is a common seasonal viral infection of the respiratory tract. For most people it feels similar to a bad cold, but it can be a serious risk for children 6 months or younger, older adults, and those with preexisting conditions. It is contagious and spreads from contact with sick people.

RSV can cause symptoms such as:

  • Low-grade fever (about 100.4 F or 38 C)
  • Dehydration
  • Coughing
  • Headache
  • Runny nose
  • Severe congestion that is not an allergic reaction.

Symptoms can last as long as two weeks, and if they are not severe, can be treated with over-the-counter medications.


Croup is a common respiratory tract infection in children 3 years old and younger. It causes inflammation that leads to a distinct barking cough and makes breathing more difficult. It is contagious and spreads from contact with sick people.

The infection can also cause fever and a hoarse voice, and symptoms are usually worst in the evening. Most children recover from croup at home in three to five days with rest.

Croup can lead to hospitalization in severe cases. Seek medical attention if your child shows signs of an inflamed, narrow airway:

  • A whistling or high-pitched sound when breathing
  • Breathing faster than normal or struggling to breathe normally
  • Difficulty swallowing or excessive drooling
  • Visible distress, anxiety or fussiness

Blue or gray skin color around the nose, mouth or fingers

In many cases, relieving symptoms and treating the illness at home is a good idea. For those at a greater risk of becoming seriously ill, and in cases where symptoms do not improve at home.