Asthma: This is often the first consideration for a nonproductive paroxysmal cough, especially if it is associated with wheezing, shortness of breath, or if it worsens at night or with exercise. Asthma can cause coughing fits that are severe and can be triggered by a variety of factors including allergens, respiratory infections, and irritants.

Gastroesophageal Reflux Disease (GERD): GERD can cause a chronic cough, which may be nonproductive and paroxysmal, especially after eating or at night. The reflux of stomach acid into the esophagus can irritate the throat and trigger coughing.
Chronic Obstructive Pulmonary Disease (COPD): While more commonly associated with a productive cough, COPD can also cause a nonproductive cough, especially in its early stages or in patients with a significant bronchospastic component.
Allergic Rhinitis: Postnasal drip from allergic rhinitis can irritate the throat and trigger a nonproductive cough. This is often accompanied by other symptoms such as sneezing, runny nose, and itchy eyes.
Upper Airway Cough Syndrome (UACS): Formerly known as postnasal drip syndrome, UACS is a common cause of chronic cough and can be nonproductive and paroxysmal. It is often associated with a sensation of something dripping down the back of the throat.

Pertussis (Whooping Cough): Although less common due to vaccination, pertussis can cause a severe, paroxysmal cough that is often nonproductive and can be life-threatening, especially in infants and young children.
Pulmonary Embolism: While typically presenting with sudden onset dyspnea, pulmonary embolism can occasionally cause a cough, which may be nonproductive and paroxysmal. This is a medical emergency.
Cardiac Conditions (e.g., Heart Failure): In some cases, heart failure can lead to a nonproductive cough due to pulmonary congestion. This would be accompanied by other symptoms such as shortness of breath, especially when lying down, and swelling of the legs.

Cystic Fibrosis: This genetic disorder can cause a variety of respiratory symptoms, including a chronic, nonproductive cough in its early stages, though it is more commonly associated with productive cough.
Bronchiectasis: A condition characterized by damaged, dilated airways, which can cause a chronic cough. While often productive, the cough can be nonproductive, especially in early or mild cases.
Sarcoidosis: An autoimmune disease that can affect the lungs and cause a variety of symptoms, including a nonproductive cough. It is less common and often associated with other systemic symptoms.
Angiotensin-Converting Enzyme (ACE) Inhibitor-Induced Cough: Certain medications, notably ACE inhibitors used to treat hypertension and heart failure, can cause a dry, nonproductive cough in some patients. This is a side effect of the medication rather than a disease process.