Diagnosing Mucus by Color: 12 Things Your Discharge May Suggest

Why is my mucus yellow? Why am I coughing up green mucus? Learn about what the color of your mucus means and what common conditions are associated with mucus.

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  1. Clear to cloudy white mucus, sometimes tinged with yellow
  2. Usually clear mucus
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  4. Yellow or greenish mucus
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Mucus, a normal, slippery, clear, protein-filled fluid, is found on the tissues within the body--such as the lining of the nose, mouth and sinuses--that come into contact with substances from the world around us. It acts both as a source of hydration and protection. It is thick and sticky in texture in order to trap unwanted substances such as bacteria, dirt, smoke and dust to prevent them from traveling deep within the body. It also contains antibodies (part of the body’s immune system) that help recognize and trap harmful potential invaders, and enzymes that help destroy those invaders. Sometimes, the color and consistency of mucus changes in reaction to changes within the body. Some mucus colors are normal, but others may mean you should pursue medical care.

Typically, clear mucus is the norm. Various bodily detritus being added to mucus is responsible for changing its color to other shades. White mucus means you’re congested as the swollen nasal tissues are slowing the mucus flow, making it lose moisture and become thick and cloudy. Yellow mucus indicates that the infection you’re suffering from is progressing. White blood cells, which fight infections, are carried off by the mucosal flow once they’ve done their job. This gives the mucus a yellowish cast. Green mucus indicates that your body is aggressively fighting the infection. If the green mucosal flow continues for more than 12 days, it might be a sign of a bacterial infection. Pink or red mucus indicates the presence of blood from broken nasal tissue, usually as a result of dryness, irritation or trauma to the area. Brown mucus can either be dried blood or some inhaled substance, such as dirt. Black mucus may indicate a serious fungal infection, which usually occurs in people with compromised immune systems.

Here are a few of the most common conditions associated with mucus and the mucus colors they are typically associated with.

Clear to cloudy white mucus, sometimes tinged with yellow

Common Cold (Upper Respiratory Infection or URI)

Colds are caused by viral infections in your upper respiratory system—your nose and throat. Over 200 kinds of viruses are responsible for colds, but rhinoviruses are the most common.

Influenza (Flu)

The viruses that cause flu are constantly changing or mutating. Influenza type A and type B viruses are responsible for the seasonal flu epidemics that occur annually.

Respiratory Syncytial Virus (RSV)

This common virus (most children have been infected with it by age 2) causes infections of the respiratory tract and lungs. RSV symptoms are mild and similar to the common cold.

Granulomatosis with Polyangiitis (Wegener’s Granulomatosis)

This rare disease causes inflammation in the nasal blood vessels, as well as those in the sinuses, throat, lungs and kidneys. The result is compromised blood flow to organs. Runny or stuffy noses, sinus infections and nosebleeds are some of the symptoms.

Cystic Fibrosis

Cystic fibrosis is progressive, hereditary disease that causes persistent lung infections marked by very thick, yellow, green, tan or brown mucus in the lungs that make breathing difficult. It’s also associated with sinusitis and nasal polyps, both of which can result in nasal mucus.

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Usually clear mucus

Non-allergic Rhinitis

Nonallergic rhinitis is characterized by chronic sneezing, nasal congestion and a runny nose. The symptoms are similar to allergic rhinitis, but no allergic triggers are present. The exact cause of this condition remains unknown, but symptoms can be triggered by changes in the weather, dry air, some medications, alcohol, certain foods and medications, spicy foods, air pollution or strong odors or emotions.

Allergic Rhinitis

Allergic rhinitis occurs when the body’s immune system somehow becomes sensitized and overresponds to something in the environment that’s harmless to most people. That could be pollen, mold, animal hair, dust mites, tobacco smoke and various foods and medications. Allergic rhinitis comes in two forms—seasonal and perennial. Seasonal allergic rhinitis (sometimes called hay fever) occurs in spring (tree pollen), late summer (ragweed) or early fall (mold spores from falling leaves). Perennial allergic rhinitis occurs year-round and can be caused by dust mites, mold and pet hair.


Some women develop rhinitis during their pregnancies. This is due to increasing hormone levels and blood production, which can cause nasal membranes to swell, dry and bleed easily as well as cause a runny or stuffy nose.

Nasal Polyps

Nasal polyps are soft, benign, painless small growths on the lining of the nasal passages or sinuses. While their exact cause is unknown, they have been linked to chronic sinusitis, allergies, recurring infections, drug sensitivity, asthma and cystic fibrosis. They can cause either a stuffed or runny nose.

Churg-Strauss Syndrome

The blood vessel inflammation caused by this rare disease can restrict blood flow to organs and tissues. While asthma is the most common sign, other symptoms also can appear, such as allergic rhinitis.

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Yellow or greenish mucus

Acute Sinusitis

In acute sinusitis, the sinuses in the nasal passages are swollen and inflamed, making it hard to breathe through the nose. The common cold is responsible for most bouts of acute sinusitis.

Chronic Sinusitis

Similar to acute sinusitis, this uncomfortable condition lasts for at least 12 weeks, despite efforts to control it. It’s caused more by prolonged inflammation rather than an infection, although that may play a part as well. Fatigue sets in, mucus builds up and breathing through the nose becomes more difficult.

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