What Does Your Snot Colour Mean?

Before tossing your next used tissue, you might want to check out the snot colour inside. As gross as it sounds, your mucus—be it clear, green, yellow, or brown—is a reflection of your overall health. Below, doctors explain how—and break down what each snot colour means.

Why snot changes colour

Snot is made up of water, proteins, antibodies, and dissolved salts, explains pulmonary disease specialist Dr Jonathan Parsons, and when you’re healthy, it appears translucent or clear. The body creates it to keep sinuses and airways hydrated and lubricated, Dr Parsons adds, and when irritants like allergens, infection, or pollutants join the mix, the sticky substance traps them (changing its colour), or its composition changes to fight off the invader.

What does green mean?

“Green phlegm is likely related to an infection,” says Dr Parsons, be it viral or bacterial. The type isn’t discernible by the colour alone, he adds, but some common ones include bronchitis, sinusitis, or pneumonia (bacterial) or an upper respiratory infection (viral). People with chronic lung disease like COPD, cystic fibrosis, or bronchiectasis, may also produce green snot. “It’s also part of environmental allergies and asthma,” Dr Parsons says.

The green colour itself can be the result of trapped bacteria, explains sleep surgeon Dr Soroush Zaghi. Or, if the infection is viral, the shade comes from the body’s defensive white blood cell secretions called myeloperoxidase, which have a green pigment, he adds.

“You’ll need to talk to your primary care provider to help figure out what may be behind the colour change,” says Dr Parsons. They might ask how long you’ve felt sick, if you’ve been around someone who has been sick, and check for fever, chills, and muscle aches or pain. “These questions will help your doctor determine if you need antibiotics,” he adds.

What does yellow mean?

Yellow snot also indicates infection. Like with green snot, yellow snot is the collection of defensive white blood cell secretions. Generally, the greener the colour, the more cells required for defence. The yellower, the fewer.

What does white mean?

“Allergies, asthma, and often viral infections cause white phlegm or phlegm without a lot of colour to it,” says Dr Parsons. Depending on the condition, chronic disease management may be necessary. “If it’s related to a viral upper respiratory infection, you can probably wait it out,” Dr Parsons explains. “If it’s allergies, you may need to take an antihistamine, a nasal steroid, or see an allergy specialist.”

What does pink or red mean?

This one is pretty straight-forward—pink or red snot is often mixed with blood. If you cough it up, Dr Parsons recommends seeing a doctor straight away, as it can be a sign of infection or cancer in some cases. “If you’re a smoker and you’re coughing up blood, it’s worrisome,” he adds. “Your doctor may take a more in-depth health history and order a chest x-ray before making a diagnosis.”

On a less serious note, excessively dry nostrils can cause frequent bloody noses that may lead to a leaky capillary, streaking snot with red.

What does brown or orange mean?

“Sometimes people who have really significant chronic lung disease can cough up a brownish phlegm,” says Dr Parsons. “Really dark brown, tenacious phlegm is seen in patients who have cystic fibrosis or bronchiectasis.” Blood and inflammation provide the brown colour, and antibiotics are sometimes required to treat it. “If you have really resistant bacteria growing in your lungs, you may need to have IV antibiotics or an aggressive regimen to keep things under control,” he adds.

Dr Zaghi says debris, smoke, or air pollution may also cause a brownish orange tinge.

What does black mean?

Charcoal or sooty looking snot tends to appear in people who work in coal mines and factories, or are really heavy smokers, explains Dr Parsons. To combat this, he recommends wearing masks in smoky or dusty work environments.

In rare, serious cases, black snot can also be indicative of fungal infection, in which case medical attention is warranted.