Asthma: This is the most common cause of wheezing, characterized by chronic inflammation, airway hyperresponsiveness, and reversible airflow obstruction. The symptoms of asthma, such as episodic wheezing, cough, shortness of breath, and chest tightness, especially at night or early in the morning, make it the first consideration in patients presenting with wheezing.

Chronic Obstructive Pulmonary Disease (COPD): COPD, including chronic bronchitis and emphysema, can cause wheezing due to airflow limitation. It's more common in smokers or those exposed to lung irritants.
Acute Bronchitis: This condition, often caused by viral infections, can lead to wheezing, especially in individuals with underlying respiratory conditions.
Pneumonia: Certain types of pneumonia, particularly those caused by viral or atypical bacterial infections, can present with wheezing.
Allergic Rhinitis: Postnasal drip from allergic rhinitis can trigger wheezing in susceptible individuals.

Foreign Body Aspiration: Especially in children, aspiration of a foreign body can cause sudden onset of wheezing and is a medical emergency.
Pulmonary Embolism: Although wheezing is not a typical presentation, in some cases, especially if there's associated pulmonary infarction, wheezing can occur. This condition is life-threatening and requires immediate attention.
Anaphylaxis: A severe, life-threatening allergic reaction that can cause wheezing among other symptoms like rash, swelling, and hypotension.

Cystic Fibrosis: A genetic disorder that leads to severe respiratory and digestive problems, including wheezing due to chronic lung infections and bronchiectasis.
Bronchiolitis Obliterans: A rare condition characterized by fixed airway obstruction, often following a respiratory infection or other insult to the lungs.
Parasitic Infections: Certain parasitic infections, such as parasitic pneumonia, can cause wheezing, though this is rare in many parts of the world.
Vocal Cord Dysfunction: A condition where the vocal cords do not function normally, leading to symptoms that can mimic asthma, including wheezing.