Cold Versus Flu

Differences between cold and flu

Influenza (flu) and the common cold are both contagious respiratory illnesses, but they are caused by different viruses. Flu is caused by influenza viruses only, whereas the common cold can be caused by a number of different viruses, including rhinoviruses, parainfluenza, and seasonal coronaviruses. Seasonal coronaviruses should not be confused with SARS-CoV-2, the virus that causes COVID-19. Because flu and the common cold have similar symptoms, it can be difficult to tell the difference between them based on symptoms alone. In general, flu is worse than the common cold, and symptoms are typically more intense and begin more abruptly. Colds are usually milder than flu. People with colds are more likely to have a runny or stuffy nose than people who have flu. Colds generally do not result in serious health problems, such as pneumonia, bacterial infections, or hospitalizations. Flu can have serious associated complications.

Key differences between cold and flu

Because colds and flu share many symptoms, it can be difficult (or even impossible) to tell the difference between them based on symptoms alone. Special tests can tell if a person is sick with flu.

Flu symptoms vs. cold symptoms

The signs and symptoms of flu can include fever or feeling feverish/chills, cough, sore throat, runny or stuffy nose, muscle or body aches, headaches, and fatigue (tiredness). Cold symptoms are usually milder than the symptoms of flu. People with colds are more likely to have a runny or stuffy nose. Colds generally do not result in serious health problems.