Expectorants or mucolytics are usually given for productive cough in the belief that they will help liquefy and loosen phlegm, making it easier to expel it from the body. Unfortunately, there is little evidence that these drugs work. The only exception to this rule is guaifenesin which the US Food and Drug Ad¬ministration (FDA) said may help in some cases.



"There's a big market out there for something called 'expectorants.' They're supposed to loosen your cough so that you can spit out the mucus in your airways. There are several different commercially available prescriptions including potassium iodide, hypertonic saline, and guaifenesin. In my view, you're probably wasting your time, money and effort on any of these preparations. With the exception of guaifenesin, which may have some liquefying effect in very large doses, I have never found these products to work," said Dr. Isadore Rosenfeld of the New York Hospital - Memorial Sloan-Kettehng Cancer Center in "The Best Treatment."

When coughing doesn't bring up phlegm or mucus, it's called dry or "unproductive." This can be triggered by ingesting cold foods or beverages which stimulate the nerves in the roof and back of the mouth. A persistent, dry cough can also be a symptom of a tumor, a heart disorder, the irritation of breathing passages from chemicals, dust and cigarettes, or the inflammation of the vocal cords.

The best treatment for this particular cough depends on what's causing it. Once the underlying condition is treated, the cough will disappear. However, it may be appropriate to take cough medicine at this time since a dry cough can be irritating and harmful in the long run.

"A harsh or forceful cough can be an irritant to the lining of the airways, just as cigarette smoke can be irritating. The act of coughing causes the air passages to contract. When this happens over and over, it leads to inflamed membranes and helps to perpetuate the cough. Coughing is similar to scratching an itch over the skin: If overdone, it can do more harm than good," according to Dr. David E. Larson, editor-in-chief of the "Mayo Clinic Family Health Book."

Faced with this problem, what medicine should you take? If the root of the problem is simple throat irritation, take honey, hard candy, or medicated throat lozenges. Look for products containing menthol or camphor. Their vapors have an anesthetic or analgesic effect on the throat.

"Some cough lozenges contain soothing substances such as honey, liquorice, or glycerin which may act on the surface of the throat. They may also contain pleas¬ant smelling and tasting substances such as pepper¬mint, eucalyptus, cinnamon, lemon, clove or aniseed. The main effect of these preparations is that their smell or taste may help you feel better. They may increase the production of saliva which is soothing and helps to wash the inflamed surface of the throat. Don't take cough medicines which contain the same ingredients in liquid form since they are swallowed directly into the stomach and only have a fraction of a second to work locally on the throat," said Andrew Chetley in "Problem Drugs."

If that doesn't work, you may need a cough suppressant or antitussive. These medicines act on the portion of the brain that controls the cough reflex. Three drugs have been approved by the FDA for this purpose: codeine, dextromethorphan, and diphenhydramine. What can you expect from these drugs? Find out in the third part of this series.

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