Should you run with a cold or the flu?

It is always difficult to know whether to run with a cold or flu.

For colds, the general rule is that running doesn’t hurt – and can actually help – if the symptoms are above the neck. If you have a cough, however, it is probably best to take the day off.

Flus are a different matter. The flu presents a greater challenger to your body’s immune system than the common cold and should not be taken lightly. has a good breakdown of what running with the flu does to your body.

So what happens if a stubborn runner decides to run during a fever-rich viral infection? The exercise has two prominent effects:

  • It takes vital energy resources necessary for recovery away from the immune system, and redirects it toward exercise. Thus immune-system activity is decreased.
  • It increases core body temperature even further, thus facilitating greater viral spread. This is most dangerous in the early stages of infection, when the body has yet to develop virus-killing antibodies.

In short, running with the flu is a bad idea. Don’t try to be a hero – rest and get better.


Special giveaway for new running book, "Science of Running"!
McMillan Running Calculator