Mucus combines with the saliva in a person’s mouth to form what is referred to as sputum. A person’s sputum can be just about any color, but sometimes it is green. Typically, the green coloring develops because of an infection in the respiratory system, and the affected person notices it after a bout of coughing. While not always a cause for alarm, the presence of green sputum may warrant the attention of a doctor.
There are many reasons mucus might mix with saliva to form sputum. Sometimes something as simple as a cold is at fault, but a person may also experience this because of an allergy or as a reaction to respiratory tract irritation brought on by smoking. Some people might even have mucus present in the mouth because of a condition called GastroEsophageal Reflux Disease (GERD), which is marked by the reverse movement of stomach acid and food particles into a person’s throat. Often, the mucus related to these conditions is clear, whitish, or yellowish, and the sputum that forms has a similar coloring. Green sputum, on the other hand, often develops because a bacterial infection is present.
A person can be affected by a variety of bacterial infections that involve the respiratory system. This means that an individual usually needs a doctor's help in determining the cause of his green sputum. Among the bacterial infections that may cause this symptom are bacterial forms of pneumonia and bronchitis as well as tuberculosis and infection of the sinuses. Though less common, infection of the larynx, which is the voice box, or the pharynx, which is a structure of the throat, causes this symptom.
Though viral conditions are not usually responsible for green sputum, they can be the starting point of the problem. For example, a common cold may fail to go away in the time expected and worsen because of the presence of bacteria that multiply and cause additional symptoms. In fact, some people first realize they have a more serious illness when they notice the green phlegm and note that their symptoms are getting worse rather than better.
Doctors do not treat green sputum since it is a symptom rather than an illness. Instead, they typically focus on the condition responsible for the mucus and the coughing that forces it into the mouth. Since bacterial infections are usually at fault, antibiotics are typically prescribed to kill the bacteria and relieve the associated symptoms.