New Treatments for Chronic Cough
Why do we cough? Coughing is a natural defense mechanism to expel excessive mucus, microbes, and irritant substances from our airways which acts to protect our lungs from the potential damage caused by them. Coughing, however, can also be a bothersome symptom and is one of the most common reasons why patients consult their doctors.
The sound of a cough is produced after forcible expiration (i.e., breathing out) against a closed glottis (i.e., voice box) as the air flows out when the glottis suddenly opens. A cough is defined as “acute” when it persists for less than 3 weeks, subacute when the duration is between 3 and 8 weeks, and chronic if it continues to be present for longer than 8 weeks.
Approximately 12% of U.S. population experiences a chronic cough at some point in their lives. It is more common in women than in men and generally peaks between the 5th and 6th decades of life. A chronic cough can be very bothersome which may negatively impact one’s quality of life. A severe cough may lead to vomiting, broken ribs, bleeding, incontinence, sleep disturbance, social distress, and/or depression.
Common causes of a chronic cough:
- Asthma
- Medications such as ACE (angiotensin converting enzyme) inhibitors and some diabetes mellitus medications
- Upper airway cough syndrome (e.g., post-nasal drip)
- GERD (i.e., gastroesophageal reflux disease) – Also known as acid reflux.
- Environmental irritants
- Tobacco use
- Eosinophilic bronchitis
- Tumors
Initial evaluation begins with obtaining a comprehensive history, which includes:
- Duration of the condition
- Characteristics of the cough
- Triggers for the cough (e.g., environmental, dietary)
- Medications taken (e.g., over-the-counter, herbal, prescriptions)
“Red flags” in the history suggesting a serious illness may include:
- Coughing up blood (i.e., hemoptysis)
- Chronic smoking with a new cough
- Difficulty in breathing
- Persistent hoarseness
- Difficulty in swallowing
- Vomiting
- Fever
- Weight less
- Swollen hands and/or feet
- Abnormal examination
- Abnormal chest X-ray
Treatments:
- Upper airway cough syndrome: Post-nasal drip is usually a result of inflammation of the nose and throat either from allergens or irritants. This condition frequently responds to either antihistamines or nasal sprays or the combination of both antihistamines and nasal sprays.
- Asthma: Cough may be the only symptom of asthma (e.g., cough variant asthma) and can be controlled with inhaled corticosteroids and/or oral leukotriene modifiers (e.g., Singulair, Accolate, Zyflo)
- Non-asthmatic eosinophilic bronchitis: A trial of oral corticosteroids such as prednisone for 1 to 2 weeks is usually helpful in relieving the cough.
- GERD: Approximately 10% of the population report frequent “heartburn” from acid reflux. Lifestyle modifications and medications to reduce acid secretion (e.g., Prilosec, Nexium, Prevacid) for 4 to 8 weeks will usually result in a substantial improvement of the cough.
- Speech evaluation and speech therapy may be useful in certain situations.
If the cough does not respond to the above treatments at the correct dosage for a sufficiently long duration, it is termed a chronic refractory cough.
New medications which target the neurological pathways and block the cough reflex are actively being investigated and are as follows:
- Sodium channel blockers: Similar to local anesthetics such as lidocaine.
- Neurokin-1 (NK-1) receptor antagonists (e.g., Orvepitant, Aprepitant)
- Purinergic receptor antagonists: Gefapixant is the name of one of the most promising drugs currently in development which exhibited significant efficacy in controlling a refractory cough. It is undergoing phase 3 clinical trials at this time. It is given by mouth twice a day. Side effects reported so far include taste disturbances.
The board certified allergists at Black & Kletz Allergy have been treating coughs in adults and children in the Washington, DC, Northern Virginia, and Maryland metropolitan area for more than 50 years. Black & Kletz Allergy provides on-site parking at all of their convenient locations in Washington, DC, McLean, VA (Tysons Corner, VA), and Manassas, VA. The Washington, DC and McLean, VA locations are Metro accessible and there is a complementary shuttle that runs between our McLean office and the Spring Hill metro station on the silver line. Please call any one of our offices to schedule an appointment for your allergy, asthma, or immunology needs. Alternatively, please click Request an Appointment and we will respond within 24 hours on the next business day.