Could Your Persistent Cough Be Something More?

Possible Causes and Evaluation of a Chronic Cough Symptom

woman coughing
What are the causes of a persistent cough?. BSIP/UIG/Getty Images

A persistent cough (or chronic cough) is a common symptom with many possible causes. Annoying effects of coughing, such as loss of sleep, sore chest muscles, and leaking urine can affect your quality of life and interfere with your daily activities. What does it mean if you have a cough that just won't go away?

It's important to first note that a persistent cough doesn’t necessarily mean you need to be worried about lung cancer.

There are many possible causes of this symptom, but since lung cancer is often missed for some time, it's important to keep this possibility in mind—even if you believe there is a good explanation for your symptoms.

Overview

A persistent cough is defined as a cough that persists for a period of eight weeks or longer. The cough may be dry or productive, in other words, you may or many not cough up mucus (sputum). This is in contrast to an "acute" cough that lasts less than eight weeks, such as those that occur with the common cold.

Possible Causes

We will start with the most common causes, but it's important to keep in mind that less common causes are not that uncommon, especially in people over the age of 50.  A significant number of people who are diagnosed with lung cancer are first diagnosed—in error—with some of these more common causes.

Most Common Causes 

  • Postnasal drip from hay fever (allergic rhinitis), sinus infections, nasal polyps, or other conditions.
  • Asthma - Though people with asthma often have other symptoms, such as wheezing and shortness of breath, in some people with asthma a cough is the only symptom (cough-variant asthma).
  • Acid reflux - Gastroesophageal reflux disease (GERD) is a common cause of a chronic cough that is often overlooked. For some people, typical symptoms such as heartburn may not be present, and the only symptom may be a chronic cough.

    Other Common Causes

    Less Common Causes 

    • Benign and malignant tumors, such as lung cancer. For two percent of people with a persistent cough, lung cancer is the underlying cause, and characteristics of a  cough related to lung cancer can be difficult to distinguish from a cough due to other causes.
    • Lung diseases such as emphysema, bronchiectasis, and sarcoidosis.
    • Fungal infections such as coccidiomycosis, histoplasmosis, and tuberculosis.
    • Inhaling a foreign object
    • Heart failure

    Common Causes in Non-Sm​okers

    A 2015 study set out to determine the most common causes of a persistent cough in people who do not smoke. It's notable that while not common, lung cancer is an important consideration even in people who have never smoked, especially if they are over the age of 50.

    In this study, the most common causes were as follows:

    • Gastroesophageal reflux (GERD) was the cause for 62 percent
    • Upper airway cough syndrome was present in 46 percent of these people
    • Cough variant asthma was present in 25 percent
    • Nonasthmatic eosinophilic bronchitis was present in 15 percent

    When Should You Worry?

    Many people worry about a chronic cough being a symptom of lung cancer, and this is for good reason. Roughly half of people with lung cancer have a persistent cough at the time of diagnosis. Currently, the average time between the onset of symptoms (such as a persistent cough) and a diagnosis of lung cancer is almost 12 months, and we know that lung cancer is most curable in the early stages.

    There are some ways in which a lung cancer cough can be different, but the truth is that there is much overlap, and you can't really tell from a cough alone whether someone is likely to have lung cancer.

    It's also important to note that a chest x-ray can easily miss lung cancer. A significant number of people who are diagnosed with lung cancer have had a "normal" chest x-ray in the year preceding their diagnosis.

    As a final note about lung cancer, keep in mind that non-smokers get lung cancer too, and lung cancer in never smokers is currently the 6th leading cause of cancer-related deaths in the United States.

    When to See Your Doctor

    It is important to make a doctor appointment if you have a cough that persists, even if you believe there is a reason to explain your cough, such as continued smoking or allergies. You should call your doctor immediately if you experience chest pain, shortness of breath or lightheadedness, or are coughing up blood.

    Questions Your Doctor May Ask

    • How long have you been coughing? 
    • Has the cough been worsening?
    • Is the cough steady or does it come and go?
    • Is it worse after meals or is it worse at night?
    • Is the cough dry, or have you been coughing up phlegm (mucus)?
    • Have you coughed up blood?
    • What other symptoms have you been experiencing? For example, fever, shortness of breath, allergy symptoms, wheezing, or unexplained weight loss?
    • What other medical problems do you have?
    • Has anyone in your family had similar symptoms? Do you have a family history of bronchitis, asthma, emphysema, or lung cancer?
    • Do you, or have you ever, smoked?
    • Have you been exposed to secondhand smoke?
    • What medications are you taking (including herbal supplements)?

    Evaluation 

    Depending on the severity of your cough, your doctor will first want to control your symptoms to make you feel more comfortable. She will then recommend tests to determine the cause. Possible exams/tests may include:

    • A careful history and physical exam
    • Blood tests to look for signs of infection
    • A chest x-ray to look for infection of any evidence of a tumor
    • A CT scan of your chest or a CT scan of your sinuses to look for signs of infection or a tumor
    • Allergy tests
    • Pulmonary function tests to screen for lung conditions such as asthma and emphysema
    • Esophageal pH testing to test for present acid reflux as a possible cause of a persistent cough
    • Bronchoscopy to check for foreign bodies or evaluate your airways for a tumor
    • Laryngoscopy to examine your throat and voice box

    Treatment

    Treatment will depend on the underlying cause, as well as the degree to which your cough is interfering with your day-to-day activities.

    Bottom Line

    If you have a chronic cough, the importance of getting checked out can't be stressed enough. It can be frustrating, especially if nothing seems to show up on tests, but hang in there. A chronic cough is not normal. Get a second opinion if you do not feel like you are being heard, or if you are not getting answers. Many of the causes—some of which are difficult to diagnose—of a chronic cough require treatment, and treatment may be more effective if these conditions are found earlier rather than later.

    Sources:

    Dabrowska, M., Grabczak, E., and M. Arcimowicz. Causes of Chronic Cough in Non-Smoking Patients. Advances in Experimental Medicine and Biology. 2015. 873:25-33.

    Damaraju, D., Steiner, T., Wade, J., Gin, K., and M. FitzGerald. A Surprising Cause of Chronic Cough. The New England Journal of Medicine. 2015. 4=373:561-566A

    Gibson, P., Wang, G., McGarvey, L., Vertigan, A., Altman, K., and S. Birring. Treatment of Unexplained Chronic Cough: CHEST Guideline and Expert Panel Report. Chest. 2016. 149(1):27-44.

    Kvale, P. Chronic cough due to lung tumors: ACCP evidence-based clinical practice guidelines. Chest. 2006. 129(1 Suppl):147S-153S.

    Udaya, B. and M. Prakash. Uncommon Causes of Cough. ACCP Evidence-Based Clinical Practice Guidelines. Chest. 129(1 Suppl):206S-219S

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