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How long is the flu contagious?

February 16, 2017 | UCI Health
when is it safe to go back to work after cold or flu?

You’ve finally kicked the worst of that flu bug, but you still feel tired and unable to shake a lingering cough. You don’t want to get anyone else sick, but deadlines are looming and your co-workers are counting on you.

When is it OK to return to work?

Dr. William C. Wilson, UCI Health chief medical officer, and Dr. Susan S. Huang, medical director of epidemiology and infection prevention, offer these tips:

  • No fever for 24 hours — without fever-reducing medications
  • No vomiting or diarrhea for at least 24 hours
  • Coughing or sneezing should be reduced and intermittent

For example, they say, if you are ill on Sunday but your symptoms have gone away by Sunday evening, you may return to work at the earliest on Tuesday.

That can be a tough pill to swallow, so to speak, when there are demands at work.

Risks of returning to work too soon

“There’s a degree of common sense involved, but also there are variables such as the risk of being taken to task for missing too many work days,” says UCI Health family medicine practitioner Dr. Robert Doomun of UCI Health — Yorba Linda.

“You also have to realize that if you go back too early, you’re probably going to relapse.”

Even worse, he adds, you might cause other people to get sick, too.

Making the right decision will depend on your energy level, your symptoms and your illness.

The most common workplace illnesses tend to be respiratory ailments such as colds and flu.

Gastrointestinal viruses, or “stomach flu," come in a close second during the winter season, says Doomun. Each has its own contagious period in which the ill person can spread sickness to others.

How long will you be contagious?

For most flu viruses, that window is about a week, starting from a day before your symptoms appear, to six or seven days afterward.

For colds, even people who are feeling better can spread the virus to others for up to three weeks. If your stomach bug was caused by a rotavirus, you can spread it to others even before you develop symptoms — and up to two weeks after you’ve recovered.

“You could feel perfect and still be shedding virus,” says Doomun. “But you can significantly reduce the risk of being contagious by waiting to return until you’ve gone 24 to 36 hours without a fever with no medicines on board. Meaning, no fever-reducing medication such as Aleve or Tylenol.”

For gastrointestinal illnesses, you should wait until you are symptom-free — no vomiting or diarrhea — for at least 24 hours.

Check your energy

Another good rule of thumb, he says, is to gauge your energy level and symptom severity. If you have at least 90 percent of your energy back and your overall symptoms have decreased by 75 percent, you are probably safe to return to work.

The opposite is also true: if you can barely drag yourself out of bed and you have a nasty cough or other symptoms, you probably should remain home until you feel better.

 If you push yourself to return to work too soon, you’ll likely delay your healing process, perform poorly and risk spreading illness throughout the workplace.

“Then two, three or even five more people will be out sick, which will severely affect the overall job site performance and productivity,” Doomun says.

Tips for returning to work after illness

When you do return, remember:

  • Wash your hands frequently and sanitize any surfaces such as computer keyboards and telephone handsets and receivers.
  • Protect your coworkers by avoiding those with weakened immune systems.
  • If you are still coughing or sneezing, wear a medical mask to prevent the spread of virus-filled droplets.
  • Sneeze or cough into a tissue or into the bend of your elbow — not your hand — to keep droplets from spreading.
  • Ease back into your work pace to allow your body to recover fully and to prevent yourself from relapsing back into illness.

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