Chronic Cough

Coughing is a protective “reflex” given to us by nature as part of our body’s vital defense mechanisms.  It forcibly expels harmful bacteria, viruses, foreign objects, and excessive mucus from the respiratory tract protecting our lungs from irritation, inflammation, and infections.

Mechanism:

There are 4 stages in a cough reflex:

  1. An initial deep inspiration filling the lungs with air.
  2. Closure of epiglottis [the flap over the opening of the windpipe (i.e., trachea)].
  3. Forcible contraction of the muscles of the chest and abdomen which pushes up the diaphragm causing compression of the lungs.
  4. As the pressure builds up, the epiglottis is forced open allowing the air to rush out at a high speed producing a whooping noise.

Coughing can be a voluntary act, conscious action, or more commonly an involuntary uncontrollable process.  The reflex is initiated by stimulation of the nerve fibers in the respiratory tract by various substances such as smoke, cold air, allergens, microbes, and tumors, as well as from irritation by normal secretions such as mucus and/or stomach acid.

All of us cough from time to time.  It is very common during colds (i.e., upper respiratory infections), which are usually viral in nature.  Coughing also is common during acute bronchitis and pneumonia (i.e., lower respiratory infections involving mainly the lungs).  It should be noted that following infections, a cough may linger for a few weeks before it subsides.

A cough that lasts for months (and sometimes years) is described as “chronic” and is one of the most common reasons why healthcare providers are consulted.  A cough may interrupt sleep resulting in daytime somnolence and affect school and work performance. Vigorous coughing may also cause physical effects such as urinary incontinence and rib fractures.

Causes:

  1. Smoking:  Most cigarette smokers eventually develop a “smoker’s cough”. Irritation by noxious chemicals is the predominant cause.  Smoke also plays a significant role in causing chronic bronchitis, emphysema, and lung cancer.
  2. Post-nasal Drip:  In addition to aiding in the perception of smell, the nose also protects the lungs by filtering, warming, and humidifying the air entering the lower respiratory tract.  It accomplishes this by secreting warm, moist, and sticky mucus. When the nose is irritated by chemicals, allergens, microbial organisms, etc., it secretes excessive mucus which is usually thin and watery.  When these copious secretions run down the back of the throat, they irritate the nerves in that area, cause a tickling sensation which may trigger a cough reflex. A post-nasal drip can often be controlled by avoiding exposure to known triggers and stimuli.  Medications such as antihistamines, decongestants, and nasal sprays may help relieve the cough caused by a postnasal drip. Home remedies such as steam inhalation and saline nasal irrigation also may play a role in treatment.
  3. Asthma:  Chest tightness, wheezing, and shortness of breath usually accompany cough in individuals with asthma.  However, in a variant of this condition, a cough may be the only presenting manifestation.  This is called cough variant asthma. The diagnosis is established by pulmonary function testing (sometimes after inhalation of a chemical (e.g., methacholine) that can trigger symptoms which can then be relieved by a medication that opens up the airways).  Occasionally, a therapeutic trial of anti-inflammatory inhaled medications (i.e., inhaled corticosteroids) on a regular basis for a few weeks is helpful in arriving at the diagnosis.
  4. Gastroesophageal Reflux Disease (GERD):  When stomach acid travels up the food pipe (i.e., esophagus), it usually causes heartburn, belching, sore throat, and/or hoarseness.  However, in one third of patients it manifests only as a chronic cough without the other symptoms. Confirmation of the diagnosis is established by placing a probe in the esophagus and monitoring the pH for acidity for 24 hours.  A simpler approach is to empirically treat the individual with lifestyle modifications (e.g., avoiding alcohol, spicy foods, citrus fruits, bulky meals, and carbonated beverages). If the symptoms persist, medications to neutralize the acid and/or reduce acid secretion may be utilized.
  5. Chronic Bronchitis:  Prolonged inflammation of the tissues in the lungs from chemical irritants and pollutants can cause a chronic cough.  Imaging studies are sometimes needed to rule out anatomical and structural abnormalities. Some patients may need long term anti-inflammatory inhaled medications (e.g., inhaled corticosteroids) to control a chronic cough.
  6. ACE inhibitors:  These medications [e.g., lisinopril (Prinivil), enalapril (Vasotec), benazepril (Lotensin), quinapril (Accupril), ramipril (Altace)] are often used to treat high blood pressure and/or heart failure.  Up to 20% of people receiving these medications may develop a cough after a few weeks, which is a known side effect of these types of medications. They may need to discontinue these medications and begin taking an alternative medication in order to get relief from their cough.
  7. Heart Disease:  Congestive heart failure can cause either a dry cough or a productive cough associated with a frothy, thin, white sputum.  Leg swelling (i.e., edema), fatigue, and exercise intolerance are other common symptoms of congestive heart failure.
  8. Aspiration:  When food finds its way into windpipe (i.e., trachea) instead of food pipe (i.e., esophagus), it triggers a recurrent cough.  This is more common in patients with strokes and other chronic neurological disorders.
  9. Lung Cancer:  It is a rare cause of chronic cough in non-smokers, and more common in smokers.
  10.  Stress:  “Psychogenic” coughing increases at times of stress and usually disappears or diminishes during sleep.
  11.  Chronic sinusitis:  It is fairly common for individuals with a chronic sinus infection (i.e., chronic sinusitis) to experience a chronic cough.  In some cases, it is the only symptom of their sinus condition.  In others, it may be accompanied by symptoms such as nasal congestion, decreased ability to smell and/or taste, post-nasal drip, discolored nasal discharge, sinus pressure, and/or sinus headaches.

Cough Medications: 

  1. Dextromethorphan is a commonly used, partially effective cough suppressant.  Prescription medications containing codeine and its derivatives are more effective but have more undesirable side effects and may be habit-forming.
  2. Guaifenesin is the most commonly used expectorant which may be useful in thinning out viscous secretions which ultimately help the mucus drain more easily.

Warning Signs:  One should consult his or her physician as soon as possible if one experiences any of the following symptoms:  bloody sputum, fever, weight loss, night sweats, breathlessness, excessive fatigue, and/or chest pain.

The board certified allergy doctors at Black & Kletz Allergy have a great deal of experience in diagnosing and treating both adults and children with a chronic cough.  It is important to find the underlying reason for a cough in order to treat it appropriately.  At Black & Kletz Allergy, we search for a cause beginning with a comprehensive history and physical examination.  Breathing tests, X-rays, blood tests, and/or allergy skin tests may be performed depending upon each individual’s history and physical, as it is tailored to each person’s own situation.

The allergists at Black & Kletz Allergy have 3 convenient locations with on-site parking located in Washington, DC, McLean, VA (Tysons Corner, VA), and Manassas, VA.  Our Washington, DC and McLean, VA offices are Metro accessible and we offer a free shuttle that runs between the McLean, VA office and the Spring Hill metro station on the silver line.  To schedule an appointment, please call one of our offices or alternatively, you may click Request an Appointment and we will respond within 24 hours by the next business day.  We have been servicing the greater Washington, DC area for more than 50 years and we look forward to providing you with excellent state of the art allergy care in a welcoming and professional environment.

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