Your head’s stuffed up, your throat is sore, and your body aches like you were run over by a truck. You feel miserable enough to stay home, but you worry that work demands don’t give you the luxury. Before you pack up your tissues and head into the office, consider the co-workers who’d rather not share your germs.

Sneezing, fever, and a hacking cough are all signs that you could be contagious. Even if you feel all right, your symptoms — or lack thereof — could be deceiving. People with mild illnesses can spread germs, too.

Here’s how to tell whether you’re contagious, and if you need to stay home.

Each time you sneeze or cough due to a respiratory infection, you release a germ-filled projectile into the air. Those bacteria- or virus-filled particles can fly up to — making anyone near you a target. You also spread bacteria and viruses when you touch your eyes, nose, or mouth and then touch surfaces with those germy fingers. Certain cold and flu germs can survive on surfaces such as countertops, doorknobs, and phones for up to 24 hours.

In general, here’s how long you’re contagious with these common illnesses:

IllnessWhen you’re first contagiousWhen you’re no longer contagious
Flu1 day before symptoms start5-7 days after you get sick with symptoms
Cold1-2 days before symptoms start2 weeks after you’re exposed to the virus
Stomach virusBefore symptoms startUp to 2 weeks after you’ve recovered

You might still be contagious when you go back to work or school. To protect people around you, take the following steps:

  • wash your hands often with warm water and soap
  • warn others that you’ve been sick so they can remember to wash their hands, too
  • sneeze or cough into your elbow, not your hands
  • consider wearing a respiratory mask
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When deciding whether to stay home, consider your symptoms. If you have a mild tickle in your throat or a stuffy nose, you should be able to go into work. Allergy symptoms also don’t need to keep you from work — they’re not contagious.

If you’re really coughing and sneezing or you feel generally miserable, do stay home. Also avoid the office if you’re vomiting or have diarrhea.

Get plenty of rest, drink lots of fluids, and wait for your symptoms to subside. The also recommends staying home for 24 hours after a fever and other flu-like symptoms (chills, sweating, flushed skin) have cleared up.

Your doctor may recommend several treatments for your illness. It is important to consider when these treatments may be helpful and their potential side effects.


The flu is a viral infection caused by the influenza virus that targets your head and chest. You’ll have symptoms such as a cough, sore throat, and runny nose. Your body will hurt, you’ll be tired, and you might run a fever over 100°F (37.8°C). People often feel the achiness and fatigue first, before their respiratory symptoms develop.

Read more: Recognizing flu symptoms »

Since they kill bacteria rather than viruses, antibiotics won’t treat the flu. Rest, fluids, and over-the-counter (OTC) pain relievers such as acetaminophen (Tylenol) or ibuprofen (Advil, Motrin) may help you manage your symptoms.

To relieve your symptoms faster, your doctor may prescribe an antiviral drug such as oseltamivir (Tamiflu), peramivir (Rapivab), or zanamivir (Relenza).

For the medication to work, you’ll need to start taking it within 48 hours of your symptoms starting. Also, antiviral drugs can cause side effects such as nausea, vomiting, and diarrhea. Relenza is an inhaled medication, so you shouldn’t use it if you have asthma or chronic obstructive pulmonary disease.

If you’re at high risk for flu complications because you’re over 65, you have a chronic health condition, or you’re pregnant, let your doctor know if you get the flu. Also call your doctor right away if you have any of the more serious flu symptoms, such as trouble breathing or dizziness.


Common colds are caused by many different viruses. These viruses spread through the air, just like influenza. When they make their way into your nose, eyes, or mouth, cold viruses cause symptoms such as a runny or stuffy nose, watery eyes, sore throat, and sometimes a cough. You might get a low-grade fever, too.

Learn more: Common cold symptoms »

Treat your cold by taking it easy. Drink water and other non-caffeinated fluids, and get as much rest as you can.

You can also take an OTC cold remedy. Some of these drugs come in multisymptom (cold, cough, fever) varieties. Be careful not to treat symptoms you don’t have, because you could wind up with side effects you don’t expect — or want. Decongestant nasal sprays relieve congestion, but if you use a certain type for more than three days, it could give you a rebound stuffed nose. Some of these drugs can also cause a spike in blood pressure or a rapid heartbeat.

If you have high blood pressure, an irregular heart rhythm, or heart disease, let your doctor know before you use a decongestant. Antihistamines can also help clear up a stuffy nose, but older ones such as diphenhydramine (Benadryl) can make you sleepy.

Colds are usually mild, but they can sometimes lead to complications such as bronchitis or pneumonia.

Shop for nasal decongestant sprays.

Your sneezing, sniffling nose and watery eyes might not be contagious at all. If they happen at certain times of the year (like spring) and they stick around for a few weeks or months, you could have allergies. Allergies can be triggered by these irritants in your environment:

  • pollen
  • pet dander
  • dust mites
  • mold

One way to tell the difference between allergies and a contagious infection is that allergies typically don’t cause symptoms such as fever and body aches.

Avoiding your triggers is the best way to ward off allergy symptoms.

To relieve allergy symptoms when they happen, try taking one or more of these medications:

  • Antihistamines, which block the effects of histamine. Your immune system releases this chemical when you have an allergic reaction. Some antihistamines can make you tired. They can also cause other side effects such as constipation and dry mouth.
  • Decongestants, which narrow blood vessels in your nose to bring down swelling and reduce running. These drugs can make you jittery, keep you awake at night, and increase your blood pressure or heart rate.
  • Nasal steroids, which control inflammation and related swelling in your nose. Some steroid solutions can dry out your nose or cause nosebleeds.
Shop for antihistamines.

Most respiratory infections clear up within a few days. Stay home until you feel better, so you don’t allow the infection to worsen — or get anyone else sick. Also hold off on returning to work if your treatments are causing side effects such as excessive drowsiness. If your symptoms don’t improve or they start to get worse, let your doctor know. You might have a bacterial infection that needs treatment with an antibiotic.