Yellow phlegm is typically a sign of a respiratory infection or sinus infection. In sinus infections, the phlegm usually appears as dark yellow or yellowish-green mucus from the nose. If the phlegm is due to a lower respiratory infection, it comes up through the throat and is coughed up. Thick, yellow phlegm can develop from a bacterial or viral infection, pneumonia, bronchitis, or the common cold. Allergies, smoking, and asthma can also produce excess mucus.
The production of phlegm is the body's way to fight a foreign substance that invades the respiratory system. The gooey phlegm clings to the lungs to trap the offending bacteria or virus. Once the germs are collected, the mucus becomes loose and travels up the throat so it can be coughed out. Tiny hairs, called cilia, help move the yellow phlegm from the lungs out of the body.
Expectorated matter, whether it is yellow or clear phlegm or mucus, should not be swallowed. It is full of bacteria that should be removed from the body. If phlegm is swallowed, it can sometimes cause abdominal bloating and excess gas. Mucus color and consistency depend on type of illness.
Some people take a cough medicine when ill to curb bouts of coughing caused by phlegm. That tactic works against the body's natural attempt to rid itself of viruses and bacteria. An expectorant to help break up the mucus is preferred by some doctors. Water and warm beverages might aid in flushing excess yellow phlegm from the lungs and nose.
Food also plays a role in how much yellow phlegm is produced and how quickly it leaves the body. Nutritionists believe caffeine, sugar, and dairy products result in excess phlegm. Beer, fatty foods, and some food additives may contribute to the problem. Other foods help clear the sinuses, such as spices containing capsaicin, horseradish, garlic, chilies, and ginger. Even chicken soup may be beneficial to clear sinuses.
To help move the phlegm along and get rid of it, steam can be effective. A hot bath or shower, or using an electric vaporizer, helps loosen yellow phlegm, along with deep breathing over a bowl of boiling water. Some people find applying heat to the chest and throat aids in coughing up mucus. Hot teas and gargling with salt water can also be effective.