Gastroesophageal Reflux Disease (GERD): This is often considered the most likely cause of chronic cough in non-smokers due to the high prevalence of GERD in the general population and its known association with cough.

Asthma: A common condition that can cause chronic cough, especially in individuals with allergies or a history of respiratory issues.
Postnasal Drip (Upper Airway Secretion Syndrome): This condition, often related to allergies or sinusitis, can lead to chronic cough due to the irritation of the upper airways.
Chronic Rhinitis: Similar to postnasal drip, chronic rhinitis can cause cough due to the continuous irritation and secretion in the nasal passages.

Lung Cancer: Although less likely in non-smokers, lung cancer can still occur and is critical to diagnose early. A chronic cough could be an early symptom.
Tuberculosis (TB): Especially in individuals who have traveled to or are from areas with high TB prevalence, this infection must be considered due to its serious consequences if left untreated.
Pulmonary Embolism: While often presenting acutely, chronic or recurrent pulmonary emboli can cause a chronic cough and are life-threatening if not diagnosed.

Bronchiectasis: A condition characterized by damaged, widened airways, which can lead to chronic cough among other symptoms.
Cystic Fibrosis: Typically diagnosed in childhood, but mild forms can present later in life with symptoms like chronic cough.
Sarcoidosis: An autoimmune disease that can affect the lungs and cause cough, among other systemic symptoms.
Foreign Body Aspiration: More common in children, but can occur in adults, especially those with neurological conditions affecting swallowing or cough reflexes.