Almost all the time we are having a cold or an infection of the upper respiratory tract, we have to deal with the phlegm. Although is not a serious health problem, leaving it untreated can cause blockage and irritation in the bronchi, causing a secondary respiratory infection.
The phlegm has bacteria, virus and other inflammatory cells and it is caused by common cold, flu, sinusitis, bronchitis, or an allergic reaction to certain irritants (rhinitis, asthma, excessive smoking, or affected vocal cords).
When we have phlegm we constantly feel the need to cough, clean our throat, or blow our nose. The phlegm will collect in the chest and cause congestion.