People sometimes use the words cold and flu interchangeably, or they use flu to mean a stomach virus, with symptoms such as diarrhea. Actually, the flu is a viral disease called influenza. It may have symptoms in common with a cold, but it’s more serious, since it can have potentially fatal complications. The flu kills 20,000 Americans each year.
For the most part, the distinction between colds and flu is not especially significant. In healthy adults younger than 65, both diseases are usually self-limiting, meaning they’ll go away on their own. Antibiotics are useless treatments for both. Depending on which strain of the virus you catch, the flu generally packs a meaner punch. Its symptoms tend to be more severe and it may last one to two weeks, as opposed to a few days to a week for a cold.
The real reason to learn the difference is the possible after-effects. A cold may sometimes lead to a secondary bacterial infection, treatable with antibiotics. But for older people and those with weak immune systems, influenza carries the potential for deadly complications.
Even healthy people should be aware when they have the flu, so they can be extra careful not to spread it to people at risk of complications. There’s also an anti-viral drug that may be appropriate and necessary for treating influenza, but is never used for colds.
The chart below compares cold and flu symptoms. Once you’re familiar with the telltale signs of each infection, it will become pretty easy for you to discern whether you have a cold or influenza.
One final note on this subject. If you develop a cough that lingers for weeks, see a doctor. It could be something that requires antibiotics, or it could be whooping cough. This contagious disease is making a comeback, both among unvaccinated children, and adults. Some adults may never have been immunized; others may have received vaccines that are no longer providing protection.
| Symptoms | Colds | Influenza |
| Runny nose/head congestion/sneezing |
Extremely common | Sometimes. May be mild and start later. |
| Sore throat | Frequently | Sometimes |
| Cough/chest congestion | Sometimes. Not often severe | Common. May have severe or dry, hacking cough |
| Fever | Very uncommon. Rarely higher than 102°F. |
High fever, often lasting a few days, is typical |
| Achy muscles | Uncommon or mild | Typical |
| Fatigue/weakness | Rare | Common. Can be severe and long-lasting |
| Headache | Rare | Common |