The main reasons for phlegm
Colds and viral infections: Viral infections such as colds and flu increase the amount of mucus in the lungs.
Allergies: Exposure to dust, pollen, pet dander, and certain odors can cause allergies in the respiratory system and increase mucus.
Winter and weather changes: Breathing cold air can cause discomfort and congestion in the throat and airways.
Smoking: Smoking slows down the function of the cells in the lungs to remove mucus, causing mucus to accumulate.
Asthma: In people with asthma, the airways become inflamed and overproduced.
Bronchitis: Infection or inflammation of the airways is a major cause of phlegm.
Sinusitis: Inflammation of the sinuses causes mucus to drain into the throat (post-nasal drip).
