Causes of Runny Nose in the Cold

Why do we get runny noses in the cold?

When we are exposed to cold temperatures, our body reacts to keep us warm. One of the ways it does this is by constricting the blood vessels in our skin to prevent heat loss. However, this constriction also affects the blood vessels in the lining of the nose, causing them to narrow and reducing blood flow through the tissues.

At the same time, the cold air we inhale when we breathe enters our warm nasal passages. This causes the humidity and temperature inside the nose to drop. The combination of reduced blood flow and the cold, dry air can irritate the nasal lining, leading to an increase in mucus production.

Mucus is produced by the glands in our nasal passages to help moisturize and protect the delicate tissues. When the nose becomes irritated, the glands go into overdrive, producing more mucus than usual. This excess mucus can drip out of the nose, causing that familiar runny nose sensation.

Additionally, the blood vessels in the nasal lining can undergo a rebound dilation after initial constriction due to cold exposure. This dilation, known as the “paradoxical reaction,” can further contribute to nasal congestion and a runny nose.

In summary, a runny nose in the cold is caused by a combination of reduced blood flow, irritation from cold air, and increased mucus production as a protective mechanism.

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