Test Your Cough IQ

Why you cough, when you cough, and how you cough -- plus a quiz to test your cold and flu smarts.

Medically Reviewed by Michael W. Smith, MD on November 08, 2010

Do you hear that coughing sound? It's cold and flu season, and people all around you are coughing. Why?

"Coughing is a normal, protective reflex," says Neil Schachter, MD, author of The Good Doctor's Guide to Colds and Flu. "We cough to clear our airways," he explains.

Think of coughing as a defense mechanism designed to rid your lungs and windpipe of substances that don't belong there. In the case of colds, this intruder is usually mucus, which builds up more than the airways can comfortably handle. At other times, the foreign substance might be something irritating, like smoke or pollution that has gotten trapped in the flypaper-like coating of the air passages.

So What Is a Cough?

First, your body senses an irritant, so the nerves in the lungs send an intruder-alert message to your brain. The brain responds by telling you to take a breath and close the epiglottis -- the small flap behind the tongue that seals off the windpipe. This causes a tremendous amount of air pressure to build up in the lungs. The chest muscles get tighter and tighter until the epiglottis is forced open, releasing the pressure in a noisy propulsion of air. In other words, you cough.

And just how forcefully do you expel air -- and with it foreign substances, such as droplets of flu virus? Well, let's just say that moving at 4 to 64 miles per hour, those droplets could get a speeding ticket.

Because you can also cough on command (such as when you clear your throat), coughing is not totally a reflex, says Schachter, who is also a professor of pulmonary medicine at Mount Sinai School of Medicine in New York City. But coughing is one of the top reasons people visit their doctors. When his patients come in to see him about their coughs, what is the No. 1 question they ask? "Is it good that I'm coughing something up? Or is bad that I'm coughing something up?" And he explains, "Well, if you've got mucus in your airways, it's good that you're coughing it up because bacteria just love to grow on [mucus]." But on the other hand, he says, "If you have an irritation and your chest is clear, then it's not necessarily advantageous to produce a lot of mucus."

Cold Coughs, Flu Coughs

Most viral infections, such as the flu, are accompanied by a pretty dry cough, Schachter says, unless some complication occurs. "Colds, which irritate the upper airways, tend to produce wetter coughs because they generate more mucus," he says. But the cough reflex is also influenced by a number of individual factors -- how sensitive you are to irritants; whether you have an underlying condition such as allergies, asthma, or bronchitis; or whether or not you smoke, for example -- as well as the type of infection.

One infectious disease that's made a comeback, Schachter says, is whooping cough, which as its name implies is distinguished by its particular sound: a fit of coughing followed by a whooping sound as you try to catch your breath. "But most coughs associated with colds and flu will ultimately get better no matter what we do," he says.

How much do you know about coughing? Test yourself with our questions here, but be sure to take our full cough quiz, too.

1.What can cause a cough?
a. Allergies
b. Acid reflux
c. Secondhand smoke
d. All of the above

Answer -- d. With allergies, a cough can be caused by postnasal drip -- mucus from your nose or sinuses that builds up in your throat. With heartburn, it might be from acid reflux -- acid that backs up into your throat. Exposure to secondhand smoke can also cause a cough.

2. If you are coughing because you have a cold or flu, it's normal to cough up mucus.

Answer -- True. Coughing up clear or yellow mucus is normal with a cold. You should see your doctor if you're coughing up mucus and have fever, chills, or shortness of breath. It could be a sign of pneumonia.

3. What kind of cough can be treated with cough medicine?
a. Asthma
b. Chronic bronchitis
c. Cold or flu
d. Pneumonia

Answer -- c. Cough medicine won't cure a cold- or flu-related cough, but it can help calm a cough. Talk to your doctor before you use cough medicine for a cough that is helping to clear your lungs -- such as one caused by smoking, emphysema, pneumonia, asthma, or chronic bronchitis. If your cough is due to asthma, it means your asthma is not under control.

4. Which of these home remedies can help calm a cough?
a. Whiskey
b. Milk
c. Hard candy
d. Chocolate

Answer -- c. Hard candies may ease a dry cough and soothe an irritated throat. Grandma might have prescribed a shot of whiskey for a cough, but there's no proof that it works. Plus, some cough and cold medicines should not be taken when drinking alcohol. Read the label. Chocolate and milk won't hurt a cough, but they won't necessarily help it.

5. You should see a doctor for a cough that lasts:
a. One week
b. More than 10 days
c. More than three weeks
d. More than eight weeks

Answer -- c. Most coughs from colds or flu go away in one to two weeks. But a cough that lingers two or more weeks after a cold or other respiratory tract infection might still go away on its own or it might need to be treated, so you should see a doctor for a diagnosis.

Show Sources

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News release, Imperial College London. 
Neil Schachter, MD, author, The Good Doctor's Guide to Colds and Flu; professor of pulmonary medicine, Mount Sinai School of Medicine, New York.
Hertzbert, J. Bulletin of the American Physical Society, 58th Meeting of the Division of Fluid Dynamics, November, 2005.
American Lung Association: "How Lungs Work."
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Roehr, B. BMJ, 2010; vol 241: p 4627.

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