How Do You Know if It’s a Cold or Flu?

Ask a Doctor

My 15-year-old son woke up with a stuffy nose and a bit of a fever. He wants to still play his football game tonight, but I don’t know if I should let him. A cold is one thing, but if he has the flu, the physical strain could be dangerous for him. How do you know if it’s a cold vs. flu?

Doctor’s Response

Either way, rest and plenty of fluids will be best for your son’s health. To prevent spreading the infection, he should stay away from people who are well until he has not had a fever for 24 hours.

Many people commonly and incorrectly confuse influenza (the flu) with the common cold. The common cold is a mild infection frequently caused by viruses other than the influenza virus.

Differentiating a cold from the flu by symptoms alone can sometimes be difficult or impossible, but in general, people with the flu get sick more suddenly, look much sicker, and feel much weaker than if the ailment were a common cold. Higher fever, body aches, extreme tiredness, and dry cough are more often symptoms of the flu, whereas runny or stuffy nose are more often associated with common colds.

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Jefferson, T., et al. "Neuraminidase inhibitors for preventing and treating influenza in healthy adults and children." Cochrane Database Syst Rev 4 Apr. 10, 2014:CD008965. doi: 10.1002/14651858.CD008965.pub4.

Mandell, Douglas, John E. Bennett, and Raphael Dolin. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases. Seventh Edition. "Influenza Viruses, Including Avian Influenza and Swine Influenza." Philadelphia: Churchill Livingstone Elsevier, 2010.

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United States. Department of Health & Human Services. "Seasonal Flu."