Common Cold Contagious Period
A person infected with a cold virus may be contagious for two to three days before any symptoms appear and remain so until he or she doesn't show any symptoms. This is a period of up to two weeks or so. The height of the "common cold contagious period" is when symptoms are at their worst -- usually around day 2 to day 4 of the cold.
An Overview of the Common Cold Contagious Period
Many people wonder, "How long is the common cold contagious?" "Is it okay to send my sick child to school?" "Am I going to catch my friend's cold?" The answers to these questions begin by understanding a couple of things.
First, scientists involved with common cold research do not know exactly how long a person with a cold is contagious. Based on previous studies, their best guess is that a person becomes contagious about two to three days before developing the usual symptoms of a cold. Second, this contagious period can last until the person no longer shows any symptoms. So in theory, a person is contagious for about two weeks.
(Click Cold Symptoms to read about the symptoms of the common cold or Cold and Flu Symptoms to learn the difference between a cold and the flu.)
Let's assume you're the one with the cold. During the two-week period when you're contagious, research indicates that you'll be most likely to transmit the cold virus when you're experiencing cold symptoms. The period when you're most contagious is when your symptoms are at their worst -- day 2 to day 4 of the cold. You'll become less contagious as the cold symptoms improve.
Keep in mind that while it is possible to transmit the common cold or "catch a cold," a cold virus is not as contagious as other viruses such as the flu virus or RSV (respiratory syncytial virus). If you have a cold, there are some things you can do to decrease the chances of spreading it (see Transmission of the Common Cold). If you are trying to avoid the common cold, there are also some prevention tips you can try (see Common Cold Prevention).
Until there is a cure for the common cold, scientists continue to perform research studies to better understand when the common cold contagious period starts and when it ends.