Main reasons for phlegm
Viral infections: Cold, flu, and viral fever are the most common causes of phlegm.
Bacterial infections: Throat infections (Bronchitis) and lung infections (Pneumonia) can cause thick phlegm.
Allergies: The body produces excess phlegm when dust, pollen, pet dander, and air pollution are inhaled (Allergic Rhinitis/Asthma).
Smoking: Smoking damages the tissues in the lungs and impairs the ability to expel phlegm.
Weather changes: Sudden cold and low humidity in the air can cause phlegm to thicken.
Asthma: People with asthma are more likely to have phlegm due to swelling in the airways.
Gastroesophageal reflux (GERD):
