I think that childhood cough is the number two leading cause of calls to the pediatrician (after fever, of course). Parents generally want that cough stopped, and sooner rather than later. Before throwing medicine willy-nilly at a coughing child, there are a few things to consider in any discussion of cough and how to treat it (or not to treat it). It only makes sense, for example, that if we can determine why someone coughs, we can arrive at a more intelligent approach to cough management.

Function of coughing

Coughing obviously serves a vital purpose. The cough reflex exists to allow the body to clear the airways and lungs of foreign substances. We should reflect on that basic fact first, before trying to eliminate coughing entirely; in other words, coughing is, generally speaking, for our own good. Any proposed treatment should improve the patient's well being without subjecting him or her to unacceptable side effects.

Mechanism of coughing

Coughs are controlled by a center in the brain that produces the coordinated activity of the body called coughing, or the cough reflex. Coughing is triggered by stimulation of nerves in the voicebox (larynx), the larger airways and smaller bronchial tubes, the lower part of the oral cavity (oropharynx), as well as the eardrum (tympanic membrane) and the external ear canal (which is why children sometimes cough when we clean the earwax).

The reflex itself consists of a coördinated sequence of events: a deep inspiration, then forceful expiration against a closed glottis1 which is then released to create a burst of high velocity air flow, expelling material from the lungs and airways, and finally followed by inspiration.

Causes of coughing

Treatment of coughing begins with a consideration of what might be the cause for the cough. What is stimulating the cough reflex? Causes can include:

  • Inflammation of the respiratory tract due to
    • infection
      • upper respiratory tract, viral: colds - by far the leading cause of coughs in children
      • upper respiratory tract, viral: croup - distinctive "barking" cough, stridor (raspy "Darth Vader" breath sounds)
      • upper respiratory tract, bacterial: rhinosinusitis
      • lower respiratory tract, viral: pneumonia, bronchitis
      • lower respiratory tract, bacterial: pneumonia
      • lower respiratory tract, mycoplasma or chlamydial: pneumonia, bronchitis
    • asthma
      • asthma itself - bronchial irritation
      • exercise-induced: cough due to bronchial cooling
    • gastroesophageal reflux - small amounts of acidic stomach contents leak into the upper esophagus, irritating the posterior part of the throat and/or seeping into the trachea (windpipe) - rare, but a consideration; cough medicines of no value
  • irritants: chemical or environmental, e.g. cigaret smoke
  • involuntary: tic or habit cough, for which no medicine works
Often the history of symptoms and signs will point to a likely cause for the cough and suggest a reasonable approach to treatment choices. At least, that is the logical place from which to start.
  • Loose, productive coughs suggest lung congestion such as that of bronchitis or asthma.
  • Loud "brassy" coughs suggest tracheitis (inflammation chiefly in the windpipe) or habit cough.
  • Stridor - the raspy "Darth Vader" breathing - implies narrowing of the airway in or just below the larynx. Sudden onset of stridor while something is in a child's mouth could mean a foreign body lodged in the larynx.
  • A staccato (rapid cough-cough-cough-cough) cough in a very young infant would suggest chlamydial pneumonitis.
  • Night cough is characteristic for both asthma and sinusitis.
  • Cough with exercise is probably exercise-induced asthma until proven otherwise.
  • Cough, especially harsh, "brassy" exaggerated cough that disappears with sleep is a classic habit cough.
  • Tight or wheezy cough in children is generally asthma (aka "reactive airway disease") until proven otherwise. This one is often missed on cursory stethoscope examination: the child must exhale forcefully to produce the wheezing, but is often reluctant to do so - knowing instinctively that this will trigger a coughing fit. But the doctor must encourage this to be sure whether wheezing is present.

Treating coughs

If a child has a viral cold, the cause of coughing is simple upper respiratory tract irritation. A suppressant may help, but until the cold is better and the inflammation and excessive mucus production subsides, we cannot expect total resolution of the cough. Research has shown that cough and cold medicines generally have limited benefit in children, and if used indiscriminantly or without careful attention to proper dosing can produce significant, even harmful side effects. This is especially true in younger children.

Or, an asthmatic child, or a child with pneumonia or bronchitis with chest congestion, is going to cough as long as there is excessive mucus or pus in the lungs. This is a natural protective reflex which cleans out the lungs the only way possible, by expelling the foreign material. We may be able to give some relief, but not only are such coughs more or less unsuppressable, but it is probably not in the patient's interest to even attempt to totally suppress the cough. We would not only be interferring with the natural process of recovery - the lung cleanup - but we would subject the child to the additional risk of side effects from the cough medicines.

We would of course prefer that there always be some "safe and efficacious" solution for children's coughs - good relief without side effects. Certainly children consume large amounts of prescription and non-prescription cough remedies. Bear in mind that considering the variety of medicines available, there is a scarcity of good evidence that cough medicines accomplish much. Some commonly used drugs or remedies include

  • guaifenesin - a liquifying agent for mucus
  • dextromethorpham - non-narcotic; the "DM" in many cough preparations; as effective (or ineffective) as narcotics
  • codeine - narcotic
  • synthetic codeine - hydrocodone "HD"
  • honey; in small studies as good or better than any of the above (!).
  • cough drops - somewhat soothing in the throat, more or less harmless
  • homeopathic (placebo) remedies - take your pick

1. glottis - a stiff flap of tissue that functions during swallowing to prevent material in the throat from flowing into the lungs.

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