Cold or flu? There’s no way to know

I really have a knack for shitty coincidences. And tempting fate.

Last Wednesday on Facebook I shared a mildly amusing thought about how super intense the flu is compared to the common cold:

People throw around the word “flu” too casually. “I think I have a touch of the flu.” There’s no such thing. Flu does not TOUCH — it’s a #%!!^%* battering ram. If you feel anything less than slammed around like a rag doll in a industrial washing machine, it’s probably not infuenza.

I was not sick when I posted that. I was not even worried that I might be coming down with something. It was just a funny excerpt from something I was writing.

Then I got sick on Thursday

And I’m now being hammered. It’s harsh. I’ve been sicker, but only a few times. And it seems worse than what I think of as a “cold,” but not quite as bad as a “flu.” So I started wondering, and reading.

Turns out we mostly can’t classify these infections as either cold or flu based on their clinical features. Why? Because “it’s complicated,” of course! As complicated as a jungle. There are just way too many species and subspecies of viruses. (And probably too much variability in the course of infections and immune reactions too.)

Turkish researchers did virus ID checks in over 5000 patients who had some kind of respiratory tract infection.1 They found a confusing mess, and notably only 33% of people had just a rhinovirus. Influenza and adenovirus viruses were more common, and many people were infected with more than one kind of virus. (And never mind the complication of bacterial infections! )

So the next time you’re sick and you’re wondering just what exactly is trying to kill you … well, keep on wondering, because you’re never actually going to know.


  1. Specifically, “pediatric and adult outpatients and inpatients who were admitted to hospital with the symptoms of upper and lower respiratory tract infections, during a 12-year period.”