Many of us discard that tissue without a second thought.

But scientists now say the color of the mucus coming from your nose could reveal hidden warning signs about your health.

Human bodies make about 100 milliliters of snot every day — equivalent to 6.5tbsp — which is mostly washed down the throat into the stomach, although some also exits through the nose. 

Doctors have spent years studying the mucus – commonly called snot – and have divided it into seven color categories, which can indicate if someone has an infection, allergy or even whether they are breathing in too much polluted air.

‘If your snot is changing color, you need to see what else is going on,’ Dr Raj Sindwani, an ear, nose and throat specialist at the Cleveland Clinic said.

‘It’s the idea that you were doing fine, nothing was bothering you, and then something changed. You’ll want to [think about] what else might have changed.’

Overall, experts said mucus should be clear in color — indicating everything is functioning normally.

But should this appearance vary or the mucus start to be produced in more copious amounts, this could indicate an underlying condition.

Nasal mucus – simply known as snot – is deeply linked to human health and can reveal how well the immune system is functioning in a person

Mucus in the nose serves a vital function in keeping airways open by trapping dust and pathogens, helping someone to keep breathing normally.

It also boosts the immune system, with the mucus containing antibodies that can attack pathogens, and humidify air that is breathed in, preventing airways from drying out and becoming irritated.

Of the colors to be concerned about, doctors say that white, cream-colored or light yellow mucus suggests the body is fighting a cold or other viral infection, as the white is caused by the white blood cells fighting off infectious intruders. 

When mucus turns denser and becomes yellowish-green, it means the body is fighting a bacterial infection or inflammation in the sinuses.

While reddish or pink snot may indicate that a small blood vessel in the nose burst at some point and the blood has now dried out. 

Apart from this, brown colored mucus can also be sign of excessive exposure to air pollutants or heavy smoking while black mucus can indicate that the body is fighting a seriou fungal infection. 

Researchers also say the amount of nasal mucus produced could also be a warning sign of a hidden complication. 

If someone’s nose produced a lot of mucus, this could be an indicator of a bacterial infection or allergic reaction to pollen – which could cause excessive mucus production by the nose.  

In rare cases, experts say it may also be a very early warning sign of Parkinson’s. 

One the earliest signs Parkinson’s patients have of the disease is a struggling to use the muscles in their nose and throat – causing saliva and mucus to accumulate in their nasal passage, according to the Parkinson’s Foundation. 

Analyzing a person’s mucus may also offer insight into Alzheimer’s disease. 

Research has also shown that the presence of excessive amyloid proteins in the nasal mucus may indicate that a person is suffering from Alzheimer’s disease. 

Alzheimer’s disease is believed to be caused by the development of amyloid plaques and tau tangles in the brain – which damage and kill cells.

Amyloid protein molecules stick together in brain cells, forming clumps called plaques. While tau proteins twist together in fiber-like strands called tangles. 

The plaques and tangles block the ability of the brain’s neurons to send electrical and chemical signals back and forth. 

Jennifer Mulligan, an otolaryngologist at the University of Florida

Over time, this disruption causes permanent damage in the brain that leads to Alzheimer’s disease.

While it remains unclear how and when the quantity of amyloid proteins increases in the snot of people, studies have noted that the presence of the proteins can be found in nasal mucus is a clear biomarker for Alzheimer’s disease in the brain. 

As a result, scientists note that examining nasal fluid early on to detect the particular proteins can help slow down the progression of the disease by starting treatments early. 

Additionally, new research indicates that examining the sticky fluid may also show whether a person is at risk of developing chronic obstructive pulmonary disease (COPD) – an inflammatory lung disease and the sixth leading cause of death in the US. 

A July 2025 study published in the Journal of Allergy and Clinical Immunology found that long-time smokers who had high levels of a protein called IL-26 in their mucus were most likely to develop COPD. 

The Swedish researchers found that high levels of the protein in the lungs and mucus of smokers was a clear sign of weak lung function and poor breathing capacity.