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'Am I Contagious?' When to Stay Home Sick

To Work or Not to Work?

Maybe it began with a tickle in your throat or a stuffy nose. The next morning, you wake up coughing and sneezing, and are faced with a serious dilemma: to work or not to work?

Everyone has a strong incentive to go to work every day — even when sick — whether it's for an important meeting, today's pay, or tomorrow's promotion. Despite such incentives, sometimes it's important for your health (and the health of others) to stay home. 

Find out what symptoms to look for to know when you're contagious, and when it's important to play it safe and stay home.

Cold, Flu, Allergies, or None of the Above?

Before you decide whether to go to work, it's important to assess what might be causing your symptoms. If you're suffering from a sore throat, runny nose, and general feeling of exhaustion, but don't have a fever, you could have a common cold, the flu, seasonal allergies, or a different virus altogether.

Both the common cold and the flu are caused by viruses. Viruses can easily spread from person to person, either through the respiratory system or through direct physical contact. You're contagious if you have a cold or the flu. 

Unlike colds and flu, seasonal allergies arise from your body's immune response to pollen. Allergies are not contagious. Therefore, you can safely go to work if you know that allergies are causing your symptoms.

It's difficult to give a foolproof diagnosis without a definitive test such as a lab test for influenza pathogens or a skin test for allergies. However, this chart, compiled by the National Institute of Allergy and Infectious Diseases, breaks down which symptoms are associated with the flu, a cold, and allergies.

SymptomColdFluSeasonal Allergies
CoughOften (moderate)Often (severe)Sometimes
Itchy eyesRarelyRarelyOften
Muscle/body achesSometimes (minor)Often (severe)Rarely/Never
Runny/stuffy noseOftenOftenOften
Sore throatOftenSometimesSometimes
Swelling of sinusesOftenRarelyOften

Still not sure what ails you? Keep reading!


If you've recently been exposed to someone with a cold, the flu, or another virus, it's likely that you have a virus as well.


Colds and the flu occur more frequently during winter months (October through April), while seasonal allergies are most common during spring and fall.


While cold and flu viruses last three to 14 days, seasonal allergies can last for weeks. Grass pollen season during the fall, for instance, lasts six weeks.

A person with the flu can often tell you the exact time of day that their symptoms started.
Dr. Stephanie Vomouras, of Health Care Service Corporation.


Typically colds and allergies begin gradually, but the flu often appears suddenly. You may experience:

  • headache
  • severe cough
  • muscle aches
  • diarrhea
  • chills
  • fever

The onset of the flu is also more noticeable because the symptoms are more severe. "A person with the flu can often tell you the exact time of day that their symptoms started," says Dr. Stephanie Vomouras, of Health Care Service Corporation.


Aside from obvious symptoms, Dr. James Malow of Advocate Illinois Masonic Medical Center explains: "Classic influenza feels like you've been hit by a truck." If your symptoms keep you from performing everyday activities, you most likely have the flu.

You need to stay home until symptoms improve if your symptoms indicate cold or flu. However, feel free to go to work if your symptoms indicate seasonal allergies.

Classic influenza feels like you’ve been hit by a truck.
Dr. James Malow of Advocate Illinois Masonic Medical Center

Cold Versus Flu

It's likely that you have a virus and are contagious if your symptoms indicate a cold or the flu. However, you might still feel well enough to go to work. Should you?

If you have reason to suspect the flu, don't go to work. Although the flu and cold might initially cause similar symptoms, the flu can cause serious complications in some people. These complications include:

  • influenza encephalitis (swelling of the brain)
  • pneumonia
  • kidney problems,
  • respiratory failure

Thousands of people die each year of influenza and its complications. In a 30-year study, the Centers for Disease Control and Prevention (CDC) reported that the number of deaths from influenza ranged from a low of 3,000 to a high of 49,000. While you might recover from the flu without complications, you could spread the virus to someone who might not be so lucky.

While few drugs work reliably against colds, antiviral drugs like oseltamivir (Tamiflu) often work effectively against flu. Better yet, the antiviral drug may make you less contagious as it starts to make you feel better. Antiviral drugs work most effectively when taken within 24 to 48 hours of the first sign of illness. The bottom line? Stay home from work and don't wait to go to the doctor if you suspect you have the flu.

Cold, Flu, and Workplace Safety

If you have a cold, you may remain contagious for as long as you have symptoms. According to the CDC, you may remain contagious for up to seven days after becoming sick if you have the flu.

Because you may still be contagious, it's important to know how to reduce your impact on others if you return to work. Use the following simple tips to help keep everyone healthy.

Avoid Direct Contact

The less time you spend with coworkers, the less likely it is that you'll make them sick.

Cover Your Cough (and Sneezes)

Because viruses travel through the air, "one way to stop the spread of illness is to practice respiratory etiquette," says Dr. Daniel Levy of Mercy Medical Center. When a tissue isn't available, use the inside of your elbow instead of your hands.

Wash Your Hands

Whether you use soap and water or alcohol-based gel, hand hygiene prevents the spread of illness by contact.

When in Doubt, Stay Home

With a busy work schedule, staying home often doesn't seem like an option for many people. If you're sick and contagious, you'll do more harm at the workplace — and to yourself — than good. When in doubt about the precise cause of your symptoms, it's best to stay home and see how you feel after a good day's rest.