Chronic cough lasting for more than four weeks is a very frustrating problem for patients and physicians alike. Most patients have seen several consultants and tried various treatments before seeing an allergist. Ultimately, chronic cough can be controlled in more than 90% of patients.
The most common causes of chronic cough are:
- Postnasal drip (due to allergic or non-allergic rhinitis and/or sinusitis)
- Cough-variant asthma
- Laryngopharyngeal reflux-LPR (stomach acid reflux reaching up to the throat)
- Post-infectious (following a cold or bronchitis)
- Reaction to a blood pressure medicine (ACE inhibitor).
Two or more causes of chronic cough are found in more than half of patients. Allergy testing and pulmonary function testing is critical to determine the cause and find effective treatment. Below is a more detailed explanation of causes and treatment options.
Drainage from the nose into the back of the throat is the most common cause of chronic cough. Allergies cause drainage as well as sneezing, itching, and congestion. Thus, allergy testing will help to determine if that is driving your symptoms. Acute sinus infections and chronic rhinosinusitis also cause drainage and cough. Depending on the situation, antibiotics are sometimes prescribed, but rinsing the nose with saline solution is always helpful. Steroid nasal sprays and antihistamines should help to lessen drainage.
Cough Variant Asthma:
As the name suggests, this is a type of asthma where the predominant symptom is cough, and the person usually has little wheezing and shortness of breath. Certainly, infections and allergies also often worsen this cough. As with all asthma, lung function testing is an integral part of diagnosis and long-term management. In this case, after allergy testing and lung function testing, the diagnosis is confirmed when a patient has a significant response to a trial of asthma medications.
Laryngopharyngeal Reflux (LPR):
Reflux of acid from the stomach into the esophagus can result in significant cough. Many patients with this problem do not have typical heartburn and are unaware of the reflux. Acid in the upper throat can irritate the vocal cords and provoke a reflex cough that at times can be severe and even lead to gagging and vomiting. Patients often describe a sensation of mucus in the throat that they are unable to cough up. Frequent throat clearing and hoarseness can also be seen with LPR. Treatment with reflux medicines can be helpful in this situation.
Many people experience a prolonged cough after a respiratory infection. Pertussis infection (“whooping cough”) in particular, can be followed by a cough which lasts up to three months, however any virus or bacteria can cause post-infectious cough. Some people with prolonged cough after an infection may also be having asthma.
Reaction to Blood Pressure Medicine (ACE inhibitor):
A small percentage of patients treated with an ACE inhibitor (example lisinopril) for high blood pressure experience a chronic cough. This can begin within days of starting, or years later. The cough is usually dry and may occur day and night. Discontinuing the ACE inhibitor and substituting a different type of blood pressure medication often results in resolution of this cough within a few weeks.