Cough: Options for Self-Treatment

Cough: Options for Self-Treatment

W. Steven Pray, Ph.D., R.Ph.
US Pharmacist 27(2), 2002. © 2002 Jobson Publishing

Introduction

Cough is one of the more common conditions for which patients request pharmacist assistance. It is usually associated with the common cold, and is thus self-treatable in most cases. However, the patient with cough may also present in the absence of any symptoms that would indicate the presence of a common cold. In these cases, the best course of action is to refer the patient for a medical evaluation.

Figure. The cough reflex occurs when certain pulmonary and bronchial receptors in the lungs are irritated.

The Physiology of the Cough Reflex

Several stimuli can induce cough. If certain afferent cough receptors in the lungs are irritated, a signal is sent via the vagal nerve.^[1] Efferent nerves then send messages that stimulate effector organs such as the diaphragm and the intercostal, laryngeal, tracheal, bronchial and abdominal musculature.^[2] A cough is the end result of this muscular stimulation.

The Phases of Cough

A deep breath is often taken before the patient begins to cough. This is known as the inspiratory phase of cough.^[1] During the next phase of cough--the compressive phase--the glottis narrows and closes. The bronchi narrow to at least 50% of the normal lumen diameter. Next is the expulsive phase, in which the glottis suddenly opens, and the patient volun-tarily makes a forceful expiratory effort, with a brief, loud sound.

The Dual Nature of Cough

The positive aspect of cough is that high airflow speed and narrowed bronchi allow excessive mucus in the airways to be moved upward, where the patient may swallow or expectorate it.^[1] Often, the patient will describe the presence of a loose bronchial congestion. If the cough is helpful in removing these pulmonary secretions, it is termed a "productive cough." The pharmacist should strive to impress upon the patient the importance of preserving the effectiveness of a productive cough through proper hydration and use of an expectorant. Should the patient fail to remove secretions effectively, pneumonia could result.

The negative aspect of cough is that coughing itself can induce cough due to airway irritation. In these cases, a cough suppressant can help stop the cycle.

Cough in Asthmatic Patients

Asthmatic patients with cough should be referred to a physician. One reason is possible diagnostic confusion. While wheezing has traditionally been the complaint that points to asthma, a certain group of asthmatic patients have cough as their predominant complaint. This is known as cough-variant asthma,^[3-5] which is a dry, nonproductive cough that is virtually omnipresent without regard to time of day, and worsens any time the patient experiences airway inflammation due to viral infection, inhalation of cold air, exercise, or allergic rhinitis. People with cough-variant asthma may not have received a firm diagnosis, yet may suspect its presence due to a positive family history or the presence of additional indicators. Rather than treating the cough in isolation, this patient must seek physician care to establish a diagnosis and to receive appropriate treatment that addresses the totality of the symptomatology. Using a cough suppressant could delay diagnosis and blur the clinical picture by the time a physician is finally consulted. Diagnosing asthma is somewhat more difficult in the patient with cough-variant asthma since typical asthma measures such as forced expiratory volume in 1 second and peak expiratory flows may be within normal limits.^[2,3] Physicians are urged to diagnose cough-variant asthma via bronchoprovocation testing using histamine or methacholine. The patient usually experiences a good response to bronchodilators and corticosteroids.

In any asthmatic individual, cough may be an early sign that the condition is worsening.^[4] In this case, the cough is usually nocturnal, presenting concomitantly with wheezing and shortness of breath. The early morning peak flow rates may also fall. Thus, the patient should seek proper care rather than treating the cough as a condition independent of and unrelated to the asthma itself.

The Smoker's Cough

Smokers often suffer cough. Parental smoking is also a major cause of cough in children.^[6]

Two types of cells line the inner lumen of the respiratory tract: ciliary cells and goblet cells. The goblet cells produce a majority of the mucus that acts to entrap inhaled pollutants, carcinogens, bacteria, and viruses. Ciliated cells act via millions of constantly moving cilia to move the mucus and entrapped foreign material upward so the person may swallow or expectorate it. Thus, this process of mucokinesis protects the healthy individual against such problems as pulmonary carcinoma, the common cold, and influenza.

Normally, the mucus is of sufficiently low viscosity that it is easily moved upward by ciliated cells. Smoking increases the volume of mucus produced in the lungs, and increases its viscosity. Smoking also decreases the activity of the ciliated cells. The pulmonary system must remove increased quantities of abnormally thickened mucus containing entrapped carcinogens, but this is simply not possible in the face of a clinically impaired muco-ciliary defense system. The result is chronic bronchitis. While some smokers have a dry, hacking cough, others report a productive cough. The productive smoker's cough is vital to supplement the impaired cilia, and must not be suppressed. This is the reason that self-treatment of cough by smokers must be prohibited.

Infective Cough

Patients are cautioned not to self-treat cough if excessive mucus is present. Bronchial or sinus infection may cause the patient to develop a cough that produces sputum. The bacteria (often Haemophilus influenzae, Streptococcus pneumoniae, branhamella, or moraxella) cause the sputum to have a yellowish or greenish color.^[4,7] Hence, excessive sputum--especially discolored sputum--requires a physician visit.

GERD-Induced Cough

Gastroesophageal reflux disease is an under-diagnosed cause of chronic cough.^[8] It causes 10% to 21% of chronic coughs.^[3] Its etiology is most often due to serial distal esophageal stimulation, though the patient might occasionally experience cough secondary to tracheal aspiration. An unfortunate fact is that most patients with GERD-induced cough do not experience additional GERD symptoms because reflux is confined to the distal esophagus and does not reach the pharynx.^[5] Thus, cough in these patients may be treated as an isolated complaint, while the unrecognized GERD continues to damage the esophagus and stimulate additional coughing. GERD-associated cough may be positively identified when anti-reflux medications help the problem, or when esophageal pH testing uncovers clear acidic changes consistent with reflux episodes.^[2,4]

Postnasal Drip

The most common cause of chronic dry cough is a combination of postnasal drip, chronic rhinitis and sinusitis.^[5] The patient with postnasal drip-induced cough will complain of secretions in the back of the throat coupled with a frequent need to clear the throat, as well as ancillary symptoms such as sneezing and nasal congestion.^[2,4,5] If congestion is profound, the patient will speak with a nasal voice. Cough may be a direct result of upper airway inflammation, or it may result from secretion-induced stimulation of laryngeal cough receptors.^[2,4] Topical corticosteroids combined with anti histamines may be helpful; premedication with topical nasal decongestants can enhance sinus penetration.

Treatment of Cough

Ingredients that are safe and effective for productive cough include guaifenesin. Nonproductive coughs may be safely treated with dextromethorphan, camphor/menthol ointments or steam inhalants, oral menthol (in lozenges, etc.), or codeine (but only in states that allow sales of codeine as a Schedule V substance).

References

Piirila P, Sovijarvi ARA. Objective assessment of cough. Eur Respir J 1995;8(11):1949-1956.
Corrao WM. Chronic persistent cough: Diagnosis and treatment update. Pediatr Ann 1996;25(3):162-168.
Patrick H, Patrick F. Chronic cough. Med Clin North Am 1995; 79(2):361-372.
Chung KF, Lalloo UG. Diagnosis and management of chronic persistent dry cough. Postgrad Med J. 1996;72(852)L594-598.
Lalloo UG, Barnes PJ, Chung KF. Pathophysiology and clinical presentations of cough. J Allergy Clin Immunol 1996;98(5 Pt 2): 591-597.
LeJeune HB, Cote DN. Passive smoking. J La State Med Soc 195;147(10):444-447.
Burns MW. Chronic cough. Aust Fam Physician 25(2):161-2,166-7.
Johnston BT, Gideon RM, Castell DO. Editorial: Excluding gastroesophageal reflux disease as the cause of chronic cough. J Clin Gastroenterol 1996;22(3):168-169.

Sidebar: ACE Inhibitor-Induced Cough

The Angiotensin Converting Enzyme (ACE) inhibitors have become mainstays in the treatment of hypertension and congestive heart failure since their introduction in the late 1970s.^[3] About 2% to 14% of people who are placed on an ACE inhibitor complain of a chronic cough.^[4] The onset varies from 3 to 4 weeks to a full year after the initiation of therapy. The cough is typically nonproductive, and worsens at night and whenever the patient assumes a supine position. For these reasons, ACE inhibitor-induced cough is often misdiagnosed as GERD-induced cough. Women and nonsmokers are suffer from ACE inhibitor-induced cough more frequently than other groups. When this type of cough occurs, it is futile to switch to another ACE inhibitor; however, the physician may attempt dose reduction. If this does not help, withdrawal of the medication will effect rapid resolution of cough, and a different group of antihypertensive agents should be chosen.

Sidebar: Patient Information: How to Treat Your Cough

Cough is a common symptom in patients of virtually all ages. The severity of cough ranges from a mild, barely noticeable, quiet cough to loud, rattling coughs that are accompanied by barking sounds. Many people cough once or twice during the day. These coughs are usually harmless attempts to clear the airways, and need not be treated. However, airway clearance can be facilitated by drinking 8 to 10 eight-ounce glasses of water daily.
Cough of the Common Cold
Almost everyone has had a common cold and can recognize its presence. In most cases, it begins with a scratchy or painful throat, followed by nasal congestion and runny nose, and the development of a cough. At first, the cough may help you raise thick secretions in the lungs to prevent pneumonia. These "productive" coughs are beneficial, and should not be stopped. Instead, you should drink lots of water, use a vaporizer or a humidifier, and take a nonprescription product containing guaifenes-in, such as Robitussin.

However, there are times when all other cold symptoms have disappeared, but a cough hangs on for several days. This dry, hacking, nonproductive cough can be halted with the use of such nonprescription ingredients as dextromethorphan (Vicks 44), topical menthol products (Vicks Vaporub, Mentholatum), menthol lozenges or tablets (Hall's), or vaporizer inhalants (Kaz Inhalant, Vicks Inhalant).

If the cough is productive but disrupts sleep, a product containing guaifenesin and dextromethorphan may be the best choice (e.g., Vicks 44-D, Robitussin DM).

When to See a Physician
There are times when a person with cough should have a professional checkup. For instance, cough in those under the age of 2 years should be evaluated by the pediatrician. Any time cough lasts longer than 7 days or recurs, a more serious underlying condition such as cystic fibrosis could be present, and a physician must be seen.

If a cough is not accompanied by runny nose or sore throat, it may not be due to a common cold at all. Some patients already suspect that the cough is caused by another problem. If it is due to smoking, asthma, or is accompanied by excess phlegm, a physician appointment should be made. You may recall a specific event, such as use of a chemical or solvent in a closed place, that preceded the airway irritation. You may have experienced lung damage from the chemical, and a check-up is a wise idea. Certain blood pressure medications ("ACE-inhibitors") can cause a chronic dry cough. If you suspect your cough is a side effect of medication, Consult Your Pharmacist. These vital beneficial medications should not be discontinued without your physician's approval.

You may experience episodes of gastroesophageal reflux, in which stomach contents travel up into the esophagus. As they damage the esophageal tissues, they can also damage some of the airway tissues and produce a cough. You may choose to try several lifestyle modifications, along with such nonprescription products as Gaviscon, Pepcid AC, Zantac 75, Axid AR, or Tagamet HB 200.

Remember, if you have questions, Consult Your Pharmacist.

W. Steven Pray, Ph.D., R.Ph., Professor of Nonprescription, Products and Devices,, School of Pharmacy,, Southwestern Oklahoma State University,, Weatherford, OK