A Cold vs. The Flu: How to Tell the Difference

The flu is running rampant this season. How do you distinguish it from its less perilous cousin, a cold? Symptoms often overlap, so when should you be concerned?

Sanaz Majd, MD
5-minute read
Episode #257

image of a man with the cold or the flu

Last week, the CDC reported that the flu death count of children so far this season has reached a high of 30. The most prevalent strain this year seems to be the H3N2, and is now widespread throughout the country. The flu is particularly threatening to the elderly and children, tragically killing up to 50,000 people in the U.S. each year alone.

Winter also brings a slew of common cold viruses which are not nearly as perilous. But the symptoms often overlap with the flu. So how do you know when it’s a cold and when it’s the flu? How do you know when you should be more concerned?

What is a Cold?

The common cold is, well…more common. It is caused by a virus that is transmitted through touch or most commonly via air droplets (via the coughing or sneezing of someone plagued with it). It is self-limiting, meaning that it resolves on its own through time. But fortunately it is rarely deadly.

People experience the following symptoms:

Check out this useful graph (via the American Rhinologic Society) depicting the course of a typical virus. Understanding this graph will help relieve any concerns about what is the normal and expected progression of a typical virus.

The common cold virus often begins as a sore throat, malaise, perhaps a mild fever (although usually none) on day one and gradually progresses to a runny and stuffy nose by day three or so, when the sore throat tends to resolve. The nasal symptoms are the most prominent and annoying feature in the common cold. As I often tell my patients, it causes a significant amount of fluid buildup in the face, resulting in symptoms like congested nasal passages, plugged ears, and a postnasal drip.

The typical common cold virus worsens each day after onset, then gradually peaks sometime between day three and five. After the peak, patients gradually improve with each day. Most people feel much improved sometime between day seven and ten.

But once plagued with the cold, all of that fluid built up has to go somewhere. So how does it exit the face? Down and out through the nostrils, or down the throat where it is swallowed (aka postnasal drip). Sorry to break it to you, but no matter how gross it seems to swallow snot, it happens to each and every one of us. That postnasal drip irritates the throat and causes a cough. Have you noticed that your cough may be waking you up at night? This is due to gravity pulling the drainage down the throat when lying down. Move the head of the bed up if this is happening to you. This exiting process can take weeks until the fluid has fully drained. This is why that nasal discharge and cough can linger on way past day seven to ten for some people.

What is the Flu?

The flu, or “influenza,” is also a virus but one that is much nastier, carrying a risk of some serious complications. Here are the symptoms of the flu:

Note the differences between a typical cold and flu virus. First, the onset of the common cold is gradual, yet it is rather sudden in the flu. Also, the fever and fatigue are much more prominent with the flu than with the common cold virus. The cold also doesn’t cause body aches typically. And unlike the flu, the nasal symptoms are a prominent feature of the cold whereas they are minimal or absent with the flu.

The common cold is no picnic, but people tend to feel dreadful with the flu when compared to the common cold virus.


Please note that all content here is strictly for informational purposes only. This content does not substitute any medical advice, and does not replace any medical judgment or reasoning by your own personal health provider. Please always seek a licensed physician in your area regarding all health related questions and issues.

About the Author

Sanaz Majd, MD

Dr. Sanaz Majd is a board-certified Family Medicine physician who graduated from Drexel University College of Medicine in Philadelphia. Her special interests are women's health and patient education.