Coughs are your body's way of clearing dust and other obnoxious (in the strictest sense) things out of your windpipe and lungs.
When your body senses that there is something in your airway that shouldn't be there, you automatically take a deep breath, close your windpipe at the "glottis" (the top of the windpipe at the back of your throat) momentarily, push air against the closed glottis with your lung muscles to build up extra pressure, and then open your glottis. When the glottis opens, the high-pressure air comes out explosively, and the explosion helps force the extraneous matter out of your airways. You can also cough whenever you want to, whether to clear your throat or for other reasons.
Although you can almost always cough when you want to, the "automatic" cough reflex is an important defense against smoke, mis-swallowed food, nasal mucus, and other things that might accidentally enter your airway. Without the cough reflex you are much more likely to develop infections or allow chemical irritation to damage your airways and lung tissue.
Sometimes you cough because of irritation to the airways with secretions -- either from inhaled irritants such as smoke and some chemicals, or infections of the upper airways. In particular, some viruses and bacteria can attack the larynx (voice box) and/or the glottis. A common example is croup, which happens when a virus attacks the larynx and windpipe. Typically a child with croup has a "barking" cough that sounds like a seal, with noise ("stridor") on inhaling. Croup usually can be treated with steam or with cool, moist air; rarely we need medicines to reduce the swelling in the larynx. Fluid in the lungs -- pneumonia -- will also cause coughing, but this is much rarer, and there are other symptoms as well. Another reason for coughing is irritation in the small airways, or bronchiolitis, or in the large airways -- bronchitis. Both bacteria and viruses can cause this kind of irritation. One particular virus that appears every winter is respiratory syncytial virus (RSV), which can also cause pneumonia as well as bronchiolitis. Asthma can also cause coughing, since the basic problem in asthma is inflammation of the airways.
Our cough reflex is not the only way we have to protect our airways. Most of the time we breathe through our noses. There are several folds and ridges at the back of the nose, on the way to the throat and windpipe, which are covered with mucous membranes. These membranes secrete mucus, a thin but slightly sticky liquid. As the air we breathe passes over these folds and ridges, it is humidified by evaporating water from the membranes and mucus, and many of the dust particles present in the inhaled air stick to the mucus so they cannot continue to the lungs. (Mucous membranes also line the windpipe and airways and help to trap smaller dust particles, and there are microscopic hairs, known as "cilia", on the surface of the lung's mucous membranes that continuously "sweep" the dirty mucus up through the airways and toward the windpipe where you can cough it all the way out.)
Sometimes, when our noses and lungs are irritated by something in the air, our mucous membranes will produce more mucus to help pick up and clean out the irritants. This can also happen when we breathe in something that we are allergic to, like ragweed pollen (the cause of "hay fever": the allergic reaction of the mucus membranes to the offending material makes the membranes produce a lot more mucus, and a lot of extra water enters that mucus because of the allergic effect on the membranes. Unfortunately, the excess mucus and water makes you very uncomfortable and doesn't do any better as far as self-cleaning goes.
Viruses can also attack the mucus membranes and cause extra watering and extra mucus production. This, in fact, is how the common cold occurs. The virus is spread from person to person through droplets in the air or on hands: remember that there's a lot of extra liquid around with all the irritation, and a lot of that is sprayed into the air every time you cough or sneeze. Other people who breathe those droplets may be infected also, since the droplets will be caught on their mucus membranes. Once you've been infected by a particular cold virus you'll be immune to it forever, but there are hundreds of cold viruses around for you to catch, and there'll almost always be a few around that you haven't had yet. Since, as with the vast majority of viruses, there are no medicines we can use to kill cold viruses, when we get a cold we have to wait it out, possibly with medicines to relieve some of the misery.
Medications of several different types are available over the counter (without a prescription) for relief of cold symptoms. I describe some of the types of medications below.
Most of these medicines have side effects, which are worse in younger patients. More to the point, none of these medicines have ever been proven to make any difference to how long a cold lasts. Neither the American Academy of Pediatrics or the World Health Organization believe that any of these medicines are any better than fluids or humidity (with one exception -- see below.). The US Food and Drug Administration has raised questions about the safety and effectiveness of these medicines in young children, especially those under 2 years old, and has announced a review of how safe and effective these medicines really are. On October 11, 2007, major manufacturers of cough-and-cold medicines for infants announced that they are voluntarily removing those medicines from the market. Subsequently, these medicines have been deemed inappropriate for any child under 4 years old. And high time, too. I do not recommend cough-and-cold medicines, except in very limited situations, and many pediatricians have said publicly that these medicines should not be used at all. (For more information and comments on cough and cold medicines, take a look at Well, a blog by New York Times columnist Tara Parker-Pope.)
Most decongestants are chemical relatives of adrenaline. Some are meant to be taken orally, while a few are made to be sprayed in the nose. If you use the nasal sprays, be careful not to use them for very long: once the spray wears off your mucus membranes will start putting out fluid again, and the more and more often you use the spray, the worse the "rebound" congestion gets. I personally recommend to my patients that they never use nasal spray decongestants for that reason. The time-release pills and capsules, in my experience at least, work as well if not better and have fewer side-effects, too -- assuming they work at all.
Since decongestants are related to adrenaline, they can make some people jittery. Small children seem to be especially susceptible to this, which is why I have never recommend decongestants in children under 6 months old. Also, you should not use decongestants if you are also using albuterol for asthma.
One problem with many of the antihistamines is that they will make you very sleepy. The most notorious antihistamine in this respect is diphenhydramine (Benadryl®), which is so sedating that many people use it, and many doctors recommend it, as a mild sleeping pill. Newer antihistamines, such as loratadine (Claritin®), do not sedate nearly as much as the older agents, but different people will have different effects from the different agents, and some people may need the sedating antihistamines for relief from their allergies.
The over-the-counter cough suppressants usually contains dextromethorphan, which is also chemically related to codeine but does not have the narcotic effects of codeine. The chemical change does not affect the cough-suppressant ability. Dextromethorphan works almost as well as codeine as far as coughs are concerned.
One problem with any cough suppressant is that getting rid of the cough may leave you unable to get rid of mucus and irritants from the lungs. It's possible to end up with pneumonia if you prevent your body from clearing the lungs regularly and automatically. Because of this, I usually recommend that children who are coughing up sputum not take cough suppressants. They can be used, however, for children with "dry" coughs -- carefully; there are potential problems with overdoses and side effects.
The World Health Organization generally does not recommend use of cough suppressants in children. However, they believe that a single dose of a cough suppressant at bedtime, in a child with a dry cough (a cough that doesn't bring anything up) may help the child by helping him to fall asleep. The American Academy of Pediatrics does not recommend cough suppressants at all, since they feel, based on clinical studies, that there is no true benefit to cough suppression even at bedtime. I personally follow the WHO recommendation and recommend cough suppressants only at bedtime and only in children with dry coughs.
There are also many cold medicines available over the counter that combine two or more of the basic preparations listed above. These combination medicines do not seem to work any better than the single-ingredient medicines they contain. Some of the combinations don't even make sense: for example, the (fairly popular) combination of a decongestant, which reduces and dries out mucus, and an expectorant, which is supposed to make mucus wetter and looser. Which one of the ingredients wins the tug-of-war isn't clear and isn't necessarily the same for different people or even for the same person at different times. I do not recommend combination medicines to my patients at all.
Humidity -- in a steamy bathroom or from a bedroom
vaporizer -- helps to thin out mucus and make it easier to cough out.
It can also soothe irritated throats and mucus membranes, and steam is the
first thing we usually try when a child has
Drinking lots of fluids also helps keep mucus thin.
Coughs are one of the most common reasons for visits to the doctor. They
are also probably one of the most common reasons for unnecessary
visits to the doctor.
Common viral colds can take anywhere from 1 to 2 weeks to clear by themselves.
When I see a child who has been coughing for only 1-2 days and has a runny
nose as well, I usually don't do anything except tell the parents to watch
the child and encourage fluids, and humidify the child's bedroom. I am
concerned mainly with:
When should we call the doctor?
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PLEASE NOTE: As with all of this Web site, I try to give general answers to common questions my patients and their parents ask me in my (real) office. If you have specific questions about your child you must ask your child's regular doctor. No doctor can give completely accurate advice about a particular child without knowing and examining that child. I will be happy to try and answer general questions about children's health, but unless your child is a regular patient of mine I cannot give you specific advice.
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Written 09/06/96; major revision 10/11/07; last revised 01/01/09
Coughs are one of the most common reasons for visits to the doctor. They are also probably one of the most common reasons for unnecessary visits to the doctor.
Common viral colds can take anywhere from 1 to 2 weeks to clear by themselves. When I see a child who has been coughing for only 1-2 days and has a runny nose as well, I usually don't do anything except tell the parents to watch the child and encourage fluids, and humidify the child's bedroom. I am concerned mainly with: