Non-Productive Cough · What Is It, Causes, Diagnosis, and More

A non-productive cough refers to a cough that is dry in nature and does not produce sputum, which refers to mucus that settles in the lower airways of lungs during an infection or chronic illness. This is in contrast to a productive cough, also known as a wet cough, where the act of coughing elicits sputum, and is typically a sign of chronic lung disease, congestive heart failure, viral illnesses, or infection. 

A non-productive cough is not necessarily bad if it is self-limiting and resolves on its own, as coughing is an important natural defense mechanism in the respiratory tract. Coughs that occur in association with an upper respiratory tract (i.e., involving the nose, pharynx, or larynx) infection typically resolve within three weeks. However, chronic coughs (i.e., a persistent dry cough lasting more than eight weeks) can lead to considerable stress and be detrimental to an individual's sleep and lifestyle. In more severe cases, chronic cough can cause rib fractures, pneumothorax (i.e., air around or outside the lung), pneumomediastinum (i.e., when air is present in the space between the two lungs), and subcutaneous emphysema (i.e., when air becomes trapped under the skin). It is important to consult with a healthcare provider if the symptoms of cough do not subside over time, as this can indicate an underlying concern.  

There are several causes of non-productive coughs, including viral illness, such as the common cold, or bronchospasm, which refers to spasms in the bronchial tubes caused by irritation. Common triggers of bronchospasm include infections, cold air, or chemicals and fumes in the environment. Allergies and post nasal drip are also common causes of a non-productive cough. In addition, blockage of the airway by an inhaled object, such as food or a pill, can lead to a non-productive cough. A chronic dry cough may also be a sign of cough variant asthma, a type of asthma in which the main symptom is a dry, non-productive cough. Asthma is characterized by swelling of the airways after exposure to an irritant, making it difficult for air to enter the lungs. Obstructive sleep apnea (OSA) is being increasingly recognized as another cause of chronic non-productive cough. OSA occurs when muscles supporting the soft tissues in the throat, such as the tongue and soft palate, temporarily relax, thereby narrowing or closing the airway, and momentarily halting breathing.

Additionally, individuals who are taking certain medications to control high blood pressure, like ACE inhibitors (e.g., captopril, enalapril maleate, and lisinopril), commonly experience a dry, tickly and bothersome cough as a side effect. Gastroesophageal reflux disease (GERD), a disorder in which acid from the stomach enters the esophagus, can lead to dry cough in approximately 40% of individuals. Lastly, early symptoms of lung cancer may include cough, chest pain, and wheezing. 

The signs and symptoms of a non-productive cough can depend on the underlying cause. If the cough is due to the common cold, the symptoms of dry coughing may persist for several weeks longer than other symptoms of the cold and the cough may worsen in the nighttime. If the cough is due to asthma, the individual may experience concurrent wheezing, shortness of breath, or a feeling of tightness in the chest. In up to 75% of those with GERD-related cough, the typical heartburn pain is not experienced, thereby making GERD more difficult to diagnose. 

A non-productive cough is usually diagnosed based on the individual's symptoms and their medical history. A clinician may ask if there was any history of sputum production or about the duration of the cough. They may also assess for potential triggers and review the individual’s medication history. They will then perform a physical examination, looking specifically at the head, neck, chest, and lungs. Imaging tests of the chest, such as X-rays or CT scans, can aid in diagnosis. Specifically, asthma can be diagnosed with spirometry, a tool in which one breathes out forcefully to measure the force of breath and capacity of the lungs. GERD can be diagnosed with upper gastrointestinal endoscopy (i.e., a procedure that involves the insertion of a flexible scope into the esophagus and stomach) and a pH acid test. A bronchoscopy may also be performed, where the tube is inserted through the mouth to visualize the trachea and airways.

Common treatments of an acute non-productive cough include taking over-the-counter (OTC) throat lozenges or taking a hot shower to ease the dryness and irritation of the throat. It is also important to treat any underlying causes. If the cause of a non-productive cough is limited to a cold, a cough suppressant containing dextromethorphan may be sufficient. If asthma and bronchospasm are present, bronchodilators can rapidly relieve coughing and other symptoms, including wheezing and shortness of breath. A commonly prescribed quick-relief bronchodilator is albuterol, which is administered through an inhaler to relax and open airways. Additionally, inhaled corticosteroids, mast cell stabilizers (e.g., cromolyn, nedocromil) and leukotriene inhibitors (e.g., Accolate, montelukast, Singulair) can all reduce airway inflammation. Other treatments include lifestyle modifications, antacids and proton-pump inhibitors for those with GERD, and antihistamines for those with allergies. If the cause of non-productive cough is ACE inhibitors, other medications to lower blood pressure may be considered, such as thiazide diuretics (e.g., hydrochlorothiazide). For those with OSA and a chronic cough, continuous positive airway pressure (i.e., CPAP) therapy can reduce or resolve the cough. 

If the etiology of cough remains unknown and treatments against potential aggravating factors do not help, antitussive agents (i.e., cough suppressants) are commonly used. In addition to dextromethorphan, a common antitussive used in clinical practice is codeine. Antitussive agents act directly on the cough center in the brain and decrease the nerve impulses to the muscles that produce cough.

A non-productive cough, also known as a dry cough, refers to a cough that does not produce sputum. There can be several causes, including viral illness, asthma, GERD, and OSA. Non-productive coughs are typically self-limiting, however, a chronic cough may signify a more serious underlying cause. Diagnosing a non-productive cough typically involves careful history taking and a physical exam performed by a clinician. Imaging, bronchoscopy, and endoscopy can also be used to aid in diagnosis. Treatment usually involves taking antitussives, bronchodilators, or corticosteroids if necessary, and treating the underlying cause.