Mystery behind runny noses finally revealed

Researchers have found out what causes one of the most common of ailments - the runny nose.

According to the scientists at the University of Colorado School of Medicine, your respiratory tract is under constant attack and the nose is the first line of defense.

Often, especially as the weather warms, the assault comes from allergens, which cause the body to fight off a perceived threat.

But millions of people get a runny nose and have difficulty breathing without an allergic attack or infection. What many people call the sniffles, scientists refer to as "non-allergic rhinitis".

Although it is common, the problem has been mysterious; researchers had not figured out why this happens - suspects include air pollution, strong emotions, even spicy food-and so have not been able to come up with a treatment beyond some variation of time, tea and tissues.

Now, the CU team led by Thomas Finger has figured out what may be going on to cause so many people discomfort. Understanding the cause could lead to figuring out a cure.

Finger and his team found cells lining the noses of mice that may be key.These cells, called solitary chemosensory cells, detect potential irritants and pass along the alert to pain-sensing nerve terminals.

The nerves then release a substance that triggers the body's defenses, called an inflammatory response. The result, among other things, is a runny nose and difficulty breathing.

The study is published in the Proceedings of the National Academy of Sciences.