Yellowish sputum usually indicates that an infection or inflammation of the respiratory system is present. Other more serious conditions and diseases can cause the body to produce yellow mucus. Sputum, also known as phlegm or mucus, is the body’s way of trapping airborne substances that enter the body through the nose or mouth in mucus, which is then spit out or expelled through the nasal passage. Sputum protects the body against invading bacteria and fungi, and helps physicians determine the type of infection or disease by the color of the sputum.
Phlegm can be caused by a variety of factors, and some yellowish sputum is normal, especially in the morning as the body rids itself of foreign bodies inhaled during the night. Dry air can cause phlegm to have a yellow tint. Most phlegm, if the person is healthy, is clear or white.
Dark yellow mucus is most commonly caused by a bacterial infection, such as pneumonia, a sinus infection, or strep throat. Colds and viruses can cause a person to cough up yellow or green mucus. Drinking large amounts of water will help to reduce the amount of yellow mucus produced if it is caused by the common cold. If the person also has a painful and forceful cough or experiences wheezing, the yellow sputum may be a result of an inflammation of the air passageways in the lungs, known as bronchitis. Pneumonia may result if the inflammation progresses and causes the lungs to become infected.
Cystic fibrosis is a genetic disease that causes thick and sticky mucus to build up in the lungs and digestive system, causing blockages. Those with this degenerative disease are frequently afflicted with lung infections and cough up yellowish sputum. Patients may also experience chronic weakness and frequent diarrhea.
Allergy sufferers often cough up yellowish sputum as their body’s immune system attacks normal foreign objects in the environment. Allergies to common substances such as hay, mold, or pollen can cause a person to have cold-like symptoms that include a cough, headache, and watery or itchy eyes. Asthma, the chronic inflammation of the air passageways, could cause a person to cough up yellow phlegm and experience wheezing and shortness of breath.
Sputum can be brown, green, yellow, and even black. If a person coughs up a red substance or bloody mucus, he or she should consult a physician. Phlegm may reflect the color of the substance the person inhaled. Laryngitis, tuberculosis, lung abscesses, or the fungus Pneumocystis carinii may also cause a person to produce colored sputum.