So Why Am I Still Coughing?
Cough is the most common complaint for which patients seek medical attention in the US. Virtually everyone coughs sometimes, but chronic cough can be a symptom of other conditions that need further investigation. Most coughing is limited to upper respiratory infections particularly in the fall and winter seasons. Chronic cough which is usually defined as cough lasting longer than 3 weeks, in an otherwise healthy nonsmoking individual with a normal chest X-ray and no recent use of blood pressure medicine in what is called the ACE inhibitor group (such as Lisinopril), will often fall into one of three categories. Postnasal drip, asthma (cough variant), and/or gastroesophageal reflux disease (GERD) are the most common causes of chronic cough in this group of patients.
This is the most common of the three causes of chronic cough. Often we see these patients to evaluate for the possibility of allergies causing their drip. We may also find nonallergic causes of their drip such as sinusitis (viral or bacterial infection of the sinus cavities) or nonallergic rhinitis depending upon the results of the history, physical exam, skin testing and/or sinus imaging with CT scans or X-rays. Often the treatment involves avoidance of allergens or irritants, medications including nasal sprays and oral antihistamines or decongestants, antibiotics, or nasal saline rinses.
Cough variant asthma is very common especially in children. In this form of asthma, the diagnosis can be elusive particularly without the common wheezing and shortness of breath with exertion. A recent chest X-ray is helpful only in screening for other causes of cough but generally will not reveal an asthma condition. The examination and pulmonary function tests may also be normal and therefore the suspicion of asthma needs to be high in patients who do not fit the first category of postnasal drip. Sometimes a trial of asthma medications or a special test called a Methacholine challenge will help identify the underlying asthma.
This is the third most common cause of persistent cough and can frequently occur in both children and adults. It also may coexist in patients with asthma further complicating the diagnosis of their chronic cough. Often associated with heartburn, not all patients will have the classic symptoms of acid reflux after meals or going to bed. Again, a careful history and high index of suspicion will make the diagnosis more likely. Dietary adjustments and lifestyle changes along with a trial of medications for reflux disease are not only helpful diagnostic aids but also part of the long term treatment.
Studies show that the cause of cough is identified 88-100% of the time and that therapy is successful in 84-98% of patients. A thorough history and a few key tests performed as part of a systematic approach will usually result in a diagnosis and successful treatment.