Respiratory infections
Colds, influenza, COVID-19, and other respiratory infections can temporarily increase mucus production.
As the immune system responds to an infection, inflammation can cause the airways to produce more secretions.
The cough may continue for some time even after other symptoms begin improving.
Allergies
Allergic rhinitis can cause significant mucus production, sneezing, congestion, and postnasal drip.
A person may feel mucus constantly running down the back of the throat and repeatedly clear their throat.
Smoking
Tobacco smoke irritates the airways and can damage the normal mechanisms responsible for clearing mucus.
People who smoke regularly may develop a chronic cough and produce more phlegm, particularly in the morning.
This is one reason persistent mucus should not simply be accepted as “normal for a smoker.”
Air pollution and irritants
Dust, chemical fumes, smoke, and polluted air can irritate the respiratory system.
People who work in construction, manufacturing, agriculture, cleaning, or other environments with airborne irritants may have increased respiratory symptoms depending on their exposures.
Asthma and chronic lung disease
Asthma can cause coughing, wheezing, chest tightness, and sometimes increased mucus.
COPD can also produce chronic cough and phlegm, particularly in people with a history of smoking or significant exposure to lung irritants.
Acid reflux
Reflux can sometimes irritate the throat and contribute to chronic coughing or throat clearing. Some people interpret this sensation as having excessive phlegm even when the primary problem is irritation from stomach contents.
This is why treating “phlegm” without understanding its cause may not solve the underlying problem.
[IMAGE 2 — Standalone article image]
Realistic documentary-style photograph of a European-looking middle-aged man outdoors in a clean urban park, experiencing a mild cough while holding a tissue, natural everyday clothing, subtle respiratory discomfort, realistic European environment, no visible mucus, no text, no logo, normal horizontal aspect ratio.