Colds and influenza (the flu) are both caused by viruses. Although they share many of the same symptoms, there are some key differences.
Colds can occur throughout the year. The flu generally infects people from late fall through early spring.
The symptoms of a cold include a stuffy or a runny nose, sneezing, sore throat, mild fatigue, headache, and a cough.
Flu symptoms are usually more severe than those of a cold and tend to come on suddenly. They can include fever (100.4 degrees F or higher), fatigue (very tired), muscle or body aches, headache, chills, sore throat, cough, and a stuffy or a runny nose. Some people may have vomiting and diarrhea, but this is more common in children than adults.
People who have the flu may be able to infect others from 1 day before getting sick until 5 to 7 days after.
Young children and people with weakened immune systems can be infectious even longer.
An annual flu shot can help prevent or reduce the severity of illness caused by flu viruses. There are no vaccines for cold viruses. It is advisable to get a flu shot every year because the vaccine is only effective for a year. Also, flu viruses are constantly changing.
The flu is more serious than a cold. According to the CDC, every year in the United States:
- Up to 20 per cent of Americans (1 in 5 people) get the seasonal flu.
- More than 200,000 people are hospitalized from seasonal flu complications, including 20,000 children.
- Up to 36,000 people die from the flu every year.
Check out this Flu Fact Sheet for tips and prevention and care during the Flu Season.
Remember, if you are sick with a severe cold or with the flu, stay home and take care of yourself. Let’s not pass it on to others.
Reviewed by: Randy Bergen, MD, October 2015
© Kaiser Permanente, 2018