'Super flu' season: Does the color of your phlegm mean anything?

There are 63 reported cases of the so-called “super flu” in the Philippines, according to the Department of Health (DOH) on Monday.

But it's also clarified that the “super flu” is not a new disease. In fact, it's only a variant of influenza A.

“Trangkaso po ‘yan sa madaling salita. Matagal na po ‘yan umiikot,” DOH spokesperson Albert Domingo said.

“Wala pong pinagkaiba yung sintomas niya sa pangkaraniwang trangkaso: ubo, sipon, lagnat, pananakit ng katawan,” he added.

[In other words, it's just the flu. It's been going around for a while now. Its symptoms are the same with the usual flu: cough, cold, fever, body aches.]

In cases where flu symptoms worsen, and your cough is accompanied by phlegm — the color of the phlegm may offer clues about what is happening in your body, including when it may be time to seek medical attention.

Dr. Joy Sy, a board-certified physician at Cardinal Santos Medical Center, points out something important: There is another thing called mucus, which is different from phlegm.

Nasal mucus is usually thin and clear. It produced by the nose and sinuses, and traps “dust, germs, and other particles before they can enter the body.”

On the other hand, phlegm, also known as sputum, is a “thick, sticky substance produced by the airways in the chest, especially when the lungs are irritated or infected.”

Does it mean anything when you cough out phlegm that's color yellow or green, brown, red, or black? 

According to Sy, phlegm color “tells us how much our immune cells are working.”

The color “mainly comes from neutrophils (white blood cells or immune cells) and their enzymes (myeloperoxidase) that accumulate during an immune response,” Sy said.

“Yellow means there is mild involvement of our neutorphils, while green means there is greater involvement of our neutrophils,” she continued.

That means, green or yellow phlegm usually indicates that the body is “fighting an infection,” commonly associated with bronchitis, pneumonia, sinusitis, and cystic fibrosis, Healthline says. 

Dr. Anna Aniag-Dimalanta, a pediatrician based in Pasig, agrees. "Yellow or greenish phlegm may indicate an infection," she says.

According to Healthline, yellow phlegm may progress into green depending on “the severity and length” of the sickness, while Aniag-Dimalanta says, "green phlegm at the very start on of an illness may also mean it’s old secretion." 

Phlegm that appears bright red, reddish, or rust-colored is a little bit more concerning. "If the color is reddish or rusty, could be tuberculosis," Aniag-Dimalanta explained.

Healthline says the color may also indicate pneumonia, lung cancer, congestive heart failure, and pulmonary embolism.

It may also suggest the “presence of blood in phlegm." 

“These findings can signal a serious underlying condition and should not be ignored,” Sy said.

Meanwhile, brown-colored phlegm may indicate “the presence of older blood,” Sy said. “While it may appear less alarming, it is still important to have this evaluated by a healthcare professional to determine the cause."

Lastly, black phlegm—medically known as melanoptysis—may indicate that a person has “inhaled a high amount of something black,” or it could point to a fungal infection, according to Healthline.

But Sy issues an important reminder: Phlegm color "cannot reliably tell us what types of organisms are present [in the body]."

"It does not tell you if the infection is viral, bacterial, fungal, or something else," she said.

As such, consulting a doctor is always advised, especially if discolored phlegm persists for more than one to three weeks.

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