Phlegm is a thick, sticky type of mucus produced by the respiratory system, primarily in the lungs and throat. While mucus normally lines airways to trap foreign particles and maintain moisture, excessive phlegm indicates an overproduction or a bothersome amount. This often signals the body is working to clear irritants or infections from the airways.
Acute Infections
Acute infections commonly cause increased phlegm production as the body’s immune system responds to invading pathogens. Viral infections, such as the common cold or influenza, stimulate mucus glands, leading to more phlegm to trap and expel viruses and cellular debris. The phlegm may initially be clear or white, but can become yellow or green as the infection progresses. However, color alone does not definitively distinguish between viral and bacterial infections.
Bacterial infections, including sinusitis and bronchitis, also trigger significant phlegm production. This phlegm is often thicker and more discolored, typically appearing yellow, green, or even brown. The increased viscosity and altered color result from the inflammatory response, where the body sends white blood cells to fight the bacterial invaders. This type of phlegm can be more challenging to clear from the airways.
Allergies and Environmental Irritants
Non-infectious factors can also provoke excessive phlegm production through inflammatory responses in the airways. Allergic reactions, triggered by substances like pollen, dust mites, or pet dander, cause inflammation in the nasal passages and throat. This leads to an overproduction of mucus, often presenting as clear, thin phlegm or noticeable post-nasal drip.
Exposure to various environmental irritants can similarly prompt the body to produce more mucus as a protective mechanism. Inhaling cigarette smoke, air pollution, chemical fumes, or strong odors can irritate the delicate lining of the airways. This constant irritation stimulates the mucus glands to produce an increased volume of phlegm, aiming to trap and remove these harmful substances.
Acid Reflux and Chronic Respiratory Conditions
Persistent or chronic conditions can also lead to excessive phlegm due to ongoing irritation or inflammation. Acid reflux, specifically Laryngopharyngeal Reflux (LPR) where stomach acid backs up into the throat, can irritate the throat lining. The body then produces more phlegm as a protective response to the acid exposure. This irritation can also cause a sensation of a lump in the throat and frequent throat clearing.
Chronic respiratory conditions involve long-term inflammation and irritation of the airways, resulting in persistent excessive mucus and phlegm. Asthma, for example, involves airway inflammation that can lead to increased mucus production, contributing to coughing and breathing difficulties. Chronic bronchitis, often linked to smoking or long-term irritant exposure, causes ongoing irritation and inflammation in the bronchial tubes. This leads to a persistent cough that produces significant amounts of phlegm as the body attempts to clear the irritated airways.
Lifestyle Factors
Certain lifestyle choices can influence the quantity and consistency of phlegm. Insufficient fluid intake, or dehydration, can cause mucus to become thicker and stickier, making it harder to clear naturally. Maintaining adequate hydration is important for keeping mucus at a healthy consistency.
While some individuals report increased phlegm after consuming certain foods, such as dairy products, scientific evidence supporting a direct link is mixed. Individual responses to dietary influences vary. However, spicy foods or cold air can sometimes lead to a more watery nasal leakage.
Smoking is a significant lifestyle factor that consistently contributes to excessive phlegm. The chemicals in tobacco smoke chronically irritate the respiratory tract, prompting the airways to produce more mucus as a protective measure. This persistent irritation often leads to “smoker’s cough,” characterized by ongoing phlegm production and difficulty clearing the airways.