What are the causes of black and green mucus?

How does mucus form? What is his job? What does the color of mucus in the nose indicate? the causes of mucus in stool? Is swallowing mucus safe?


Mucus is a natural, slippery liquid substance produced by many lining tissues in the body. It is essential for body function and acts as a protective and moisturizing layer to prevent vital organs from drying out.

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Mucus also acts as a trap for irritants such as dust, smoke or bacteria, and contains bacteria-killing antibodies and enzymes to help fight infection.

How is mucus formed?

The body’s lining tissues produce about 1 to 1.5 liters of mucus per day. We do not tend to notice mucus at all unless its production increases or its quality changes, as happens with various diseases and conditions.

What is mucus?

Mucus is more than just a sticky substance. It contains antibodies that help the body recognize invaders such as bacteria and viruses, enzymes that kill trapped invaders, proteins that make mucus sticky, and a variety of cells.

Where does the mucous fluid come from?

Mucus is produced in many locations in the body by mucus glands in the tissues lining multiple organs, including the lungs, sinuses, mouth, throat, nose, and digestive system.

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Color of mucus

The color of your mucus can tell you many things, including whether you have allergies, nosebleeds, a cold, or sinusitis.

Clear mucus

In general, this is a normal situation. But for your information, allergies can appear this way as well. Clear mucus consists mostly of water and contains proteins, antibodies, and dissolved salts. And your nasal tissues produce them 24/7.

Most of it flows down the throat to dissolve in the stomach.

White mucus

It may be a sign of a nasal infection or a cold.

Yellow mucus

This could mean a cold or infection is getting worse. The yellow pigment comes from white blood cells that rush to the site of the injury and are then eliminated after working to fight it.

Green mucus

It may indicate an infection, in which case your immune system fights the infection and the mucus becomes thick with dead white blood cells.

Pink or red mucus

The nasal tissue in the nose has been injured in some way, perhaps because it is dry or irritated, resulting in a nosebleed.

Brown mucus

It may be caused by something inhaled such as dirt or snuff.

Black mucus

It may occur as a result of breathing in dirt that collects in the nasal mucus. In rare cases, black mucus may indicate a serious fungal infection.

Mucus in stool

The presence of mucus in the stool can be common. They can be common causes of constipation, dehydration, Crohn’s disease and irritable bowel syndrome.

When you are generally healthy, the mucus is usually clear and appears in small amounts that are often difficult to notice.

But if you start seeing a noticeable increase in mucus in your stool, it could be a symptom of a health problem.

Causes of mucus in stool

Two common causes of mucus in stool are dehydration and constipation. These two conditions may cause the natural mucus in the colon to leave the body. The mucus caused by these problems may resolve on its own or with medications.

Changes in mucus levels may also be the result of an inflammatory condition in the digestive system that requires medical treatment, such as:

  • Crohn’s disease
  • Cystic fibrosis
  • Ulcerative colitis
  • Irritable bowel syndrome
  • Intestinal infection
  • Malabsorption
  • Colon or rectal cancer

Benefits of mucus

Mucus-producing tissues line the mouth, nose, sinuses, throat, lungs, and digestive system. The mucus acts as a protective covering over these surfaces, preventing the tissues underneath from drying out.

Mucus also acts as a kind of barrier, trapping unwanted substances such as bacteria and dust before they enter the body, especially the sensitive airways.

Cough accompanied by mucus

Coughing is the rapid expulsion of air from the lungs, usually to clear the airways of fluid, mucus, or matter.

Respiratory infections such as colds, influenza, and sinusitis are common causes of increased mucus production and coughs accompanied by mucus.

Allergic reactions are another cause of increased mucus production, and consuming spicy foods can lead to increased secretion in the nasal passages.

When you are sick from a respiratory infection, you may notice thick mucus that may appear darker than usual. This thick mucus is more difficult to clean than its usual counterpart.

The presence of this mucus is often linked to the typical symptoms experienced during a cold or flu, adding to the discomfort and inconvenience caused by these illnesses. It may appear yellow-green when you are sick.

Phlegm and mucus can result from seasonal allergies or respiratory infections.

What is the difference between mucus and phlegm?

Mucus and phlegm are often used interchangeably, but they are not the same. A mucus is a clear liquid secreted by mucous glands in the body’s lining tissues to protect and lubricate them. Additionally, it serves as a barrier that captures irritants such as dust, smoke, and bacteria.

On the other hand, phlegm is a thicker, stickier substance that is produced in the lower airways of the respiratory system, such as the lungs and bronchi. It contains a mix of mucus, dead white blood cells, and inflammatory cells.

Swallow mucus?

It may seem gross, but swallowing mucus is actually normal and can help prevent infection. Nose blowing forces bacteria-filled mucus from your sinuses into your ears and throat. Swallowing this mucous keeps it out of your ear passages.


Mucus is an essential substance in the body, produced by various tissues to protect and moisturize them. It also plays a crucial role in trapping foreign invaders and preventing infections.

The color and consistency of mucus can indicate different health conditions, and it is essential to pay attention to any changes in mucus production or quality.

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This site provides educational information only. It is important not to depend on any content here in place of professional medical advice, diagnosis, or treatment. Similarly, it should not replace professional counseling care, advice, diagnosis, or treatment. If you have any health concerns or questions, always seek guidance from a physician or another healthcare professional.