Infections are the most common cause of illness in otherwise healthy people. The vast majority of these infections are caused by viruses, especially respiratory illness associated with cough, sore throat and runny nose.

There are many different kinds of viruses that cause colds. Within those groups of viruses there are many different strains of viruses. This means your child can get many colds in a year in both the summer and the winter, although these illness are more common in the winter. Although you develop immunity to a virus when you have an infection, for these types of illnesses, that immunity reduces over time, so you will be able to be infected with the same virus every few years.

This is why the common cold is so common.

In general, an illness with cough, sore throat and sneezing/runny/stuffy nose is a viral upper respiratory infection, or “common cold." Colds can occur with or without fever. Usually, if there is a fever associated with a cold, it occurs in the first few days of the illness and then resolves. Other symptoms may persist for days, and up to one to two weeks, depending on the particular virus.

As time goes by, symptoms should slowly improve. Nasal discharge will turn from clear to yellow to green. This is normal during a cold and does not indicate a bacterial sinus infection. This graph from the Centers for Disease Control and Prevention shows the typical duration of various cold symptoms.


In addition to common cold viruses, there are many viruses that cause fevers or fevers with rashes or other symptoms. Many of these viruses such as chicken pox, measles, mumps and rubella are now prevented by vaccines. These infections are now very rare because of the amazing vaccines used to prevent them. There are other viral illnesses that can make your child sick for a few days, often with fever, but also resolve on their own like colds. These include roseola, fifth disease (slapped cheek disease), hand, foot and mouth disease and many others.

Antibiotics do not help any of these illnesses resolve more quickly. Taking an antibiotic when it will not help only exposes you or your child to possible side effects like rashes and diarrhea with no expectation of any benefit. When a doctor says you have a virus, that tells you antibiotics are not necessary at that time. Your doctor should not give antibiotics when she thinks an infection is due to a virus, so there is no reason to go to the doctor unless you or your child are not getting better the way you expect from the graph above. 

Sometimes when you have an infection with a virus results in a bacterial infection. This does not occur in most cases but is most likely to occur in young children and the elderly. Examples include ear infections (otitis media), bacterial sinus infections or pneumonia. These are infections for which antibiotics may be indicated, and it is reasonable to go to the doctor.

How do you know when you or your child may be developing a bacterial infection?

  • Fever - From the graph, you can see that fever usually lasts only a few days at the onset of the illness. If the fever goes on for longer than 2-3 days or goes away and comes back a few days later, that could be the result of a bacterial infection.
  • Ear pain - especially with new or persistent fever, this could indicate an ear infection.
  • Persistent or worsening nasal discharge – if nasal discharge persists without improving or is getting worse after 10 days, or sooner if associated with a new fever, you could have a bacterial sinus infection.
  • Worsening cough, difficulty breathing or chest pain, especially with new or persistent fever, could indicate pneumonia.
  • Worsening cough and difficulty breathing in young children (less than 2 years) - certain types of respiratory viruses can cause difficulty breathing after having cold symptoms for a few days. Have your child seen by a doctor if this occurs, regardless of presence of fever, because sometimes children will need support for their breathing with oxygen until they get over this illness.