Colds and the flu have so much in common that it can sometimes be hard to tell them apart. Both are caused by viruses that infect your airways. They have some of the same symptoms that can leave you feeling miserable.
There are enough differences, though, that may help you figure out which one you have. That can change how you treat your symptoms.
You can get a cold anytime -- spring, summer, or fall, but most likely in winter.
Flu season typically runs from November through March, although you can get it in October or as late as May. You can catch the flu at other times of the year. But symptoms outside of flu season are more likely to be from a cold or an allergy.
Flu tends to be much worse than a cold. And the flu, especially in children and older people, is more likely to lead to serious health problems such as pneumonia and a hospital stay.
Rarely, symptoms may not be enough for your doctor to know if it's a cold or the flu. Then she may do a test to find out what you have.