It may seem overly precautious to stay home at the first sign of illness, but in terms of a cold or the flu, you are most contagious during this time, says Judah Fierstein, MD, of Mount Sinai Urgent Care in New York City. "From a contagion standpoint, the very first days of the illness, and even the day before, is the time where you don't want to have your desk partner next to you," he says. He suggests taking off as soon as it's clear that you are getting sick—your throat's sore, your body aches, and your head's pounding. "You might have the ability to intervene by really resting and just taking good care of yourself and therefore shorten the illness overall."
Some of us run hotter than others, says Aileen M. Marty, MD, director of the Florida International University Health Travel Medicine Program and Vaccine Clinic in Miami. Still, if your thermometer reads over 100 degrees Fahrenheit, you should just stay in bed. "If you've got a fever, then something is wrong enough in your system that your brain has set your temperature higher in order to kill off something that it is perceiving as a danger," she says. Steer clear of the office until you've been fever-free for 24 hours to avoid spreading contagious illnesses to co-workers.
You know you won't be productive
Aside from the possibility of infecting your co-workers, it's important to assess just how much you'll actually get done if you tough it out and head to work. If your sickness disrupts your ability to do work, you won't impress anybody by coming in. "I think you are more likely to be fired for being unproductive or messing something significant up than calling out for a day or two," says Dr. Fierstein.
You aren't getting better
After battling mild to moderate symptoms for a few days, you should start to recover. If not, it's time to take a day off and consider checking in with a doctor, says Dr. Marty. "Even if it's not a significant problem, that's enough to be a red flag," she says. Your body may just need some solid downtime to begin to repair itself.
You're taking medication with side effects
Just because you pay a visit to the doctor and are prescribed medication, doesn't mean that you are in the clear. Some treatments have side effects that can make getting work done difficult. One example is medication that may cause drowsiness. "It can put you at risk if you are driving or using heavy machinery," says Dr. Marty. "You're much better off staying at home, getting over it and getting back to work even more productive afterward."
This article originally appeared on Health.com