What ailment causes you to have a constant cough with phlegm?

Ailments that cause a constant cough with phlegm are tuberculosis, bronchiectasis and lung abscess, according to Mayo Clinic, the National Institutes of Health, and the National Heart, Lung and Blood Institute. A lung abscess is an infected area of lung tissue. The patient coughs up phlegm that is sometimes streaked with blood. Lung abscesses are often complications of other lung diseases and are difficult to treat.

Bronchiectasis is a lung condition in which the bronchial tubes in the lungs are scarred and flabby, and thick secretions begin to accumulate, states the National Heart, Lung and Blood Institute. Tuberculosis is a serious contagious bacterial infection of the lungs, states Mayo Clinic.