The Good Cough
Ever notice that everyone describes his cough as “bad”? This post is a somewhat tongue-in-cheek defense of the lowly cough (except for those who cough in theaters, which should be a hanging offense.)
Why do we cough? To clear our airway of bothersome stuff: pollen, bacteria, viruses, toxins and the cellular reaction to them, collectively known as mucus. If not for the cough reflex our lungs would be like vacuum-cleaner bags.
When do we cough? The timing can indicate the cause. Exercising, especially in dry windy weather triggers an asthmatic cough in many people. Breathing via the nose helps humidify and warm the air, but I can attest to how difficult it is to do that while running. Night coughs may signify the common “post-nasal drip” one gets with colds and allergies.
The lining of our respiratory tract consists of microscopic cells with cilia, tiny hair-like structures that sweep invaders away from the lungs; these in turn are interspersed with cells containing goblets of mucus. Some infections such as influenza can destroy this delicate lining, which is why it takes three weeks to recover while the new lining grows. Smokers lose this defensive layer and it is replaced by squamous epithelial cells similar to skin cells, not only ineffective but prone to cancer.
Cough is different in babies for many reasons. They spend a great deal of time on their back, their muscles are relatively weak and their immune systems are rather slow to respond especially if not breast-fed. Respiratory viruses tend to be nastier the first time a baby encounters them, whereas the same virus appearing in later years will cause a simple cold. Children’s coughs are so ineffective that cases of tuberculosis under age 10 are not considered contagious (although no one seems to haver told this to the folks who make 3-year-olds get TB tests before attending pre-school).
Treatment of cough has changed dramatically in recent months with the withdrawal of all over-the-counter cough and cold preparations for kids under 2 (perhaps soon to be followed by further restrictions). The evidence for efficacy in babies was never established, and the dizzying array of new multi-symptom preparations was leading to overdoses. So now what? It’s back to your great-grandma’s remedies: moisture, positioning, suctioning, herbal tea, chicken soup, and good old honey (except under one!!) People ask about Vicks Vaporub and I have no idea if the stuff works or is safe, so you’re on your own! Much of the help we get from cough medicines is the topical anesthetic action on the throat, which is why cough drops have enjoyed a new life. Cough syrups taste awful because they contain things like chloroform and phenol; if you wash them down with water right away they don’t do much good. The most common ingredient in cough preparations is “DM”, a synthetic codeine imitator which has never impressed much in controlled studies. There are prescription medicines for cough, mostly with codeine. I feel that they are overused. If I’ve examined the patient and feel the cough is “useless” and lack of sleep is becoming an issue (for the child, not the parents) I’ll give an Rx for nighttime use only, and almost never in an asthmatic.