Does Cold Exposure Increase the Risk of Upper Respiratory Infections?

At Nebraska Health and Wellness Clinic, we often hear the belief that exposure to cold temperatures makes people more susceptible to illness. Many assume that being outside in the winter, walking barefoot on cold floors, or failing to bundle up will inevitably lead to catching a cold or flu. But is there actual scientific evidence to support this, or is it just a long-standing myth?

In this forum, we’ll examine both perspectives:

1. Does cold exposure weaken immunity and increase the risk of respiratory infections?

2. Does cold exposure have no direct impact on immune function and infection susceptibility?

The Case for Cold Exposure Increasing Infection Risk

There are a few mechanisms by which cold exposure could theoretically contribute to a higher risk of respiratory infections:

Vasoconstriction and Mucosal Immunity: When exposed to cold temperatures, blood vessels in the nose and respiratory tract constrict. This can reduce blood flow and potentially limit immune cell activity in the mucosa, weakening the first line of defense against viruses and bacteria.

Dry Winter Air & Viral Transmission: Cold air often has lower humidity, which can dry out the mucosal linings of the respiratory tract, making it easier for viruses like influenza and rhinoviruses to invade. Studies suggest that flu viruses are more stable and remain airborne longer in dry, cold air.

Indoor Crowding & Reduced Ventilation: People tend to stay indoors more during colder months, increasing close-contact exposure to others. This allows for easier transmission of viruses and bacteria, rather than the cold itself being the direct cause.

One study published in Proceedings of the National Academy of Sciences (PNAS) found that colder temperatures can impair the immune response in nasal cells, making them less efficient at fighting off infections.

The Case Against Cold Exposure Causing Illness

On the other hand, research does not definitively prove that simply being cold directly weakens the immune system or causes infections. Arguments supporting this viewpoint include:

Viruses and Bacteria Cause Illness, Not Temperature: The common cold and flu are caused by viruses, not exposure to cold air. If a person is not exposed to a pathogen, they won’t get sick just from being in the cold.

Cold Exposure and Immune Adaptation: Some studies suggest that brief exposure to cold (such as cold showers or winter swimming) may actually enhance immune function over time by increasing white blood cell activity and improving circulation.

Limited Impact of Cold on Core Body Temperature: While extreme cold can be dangerous (hypothermia, frostbite), typical cold exposure does not significantly lower core body temperature enough to weaken immune defenses.

A study from The New England Journal of Medicine tested whether cold temperatures alone increase susceptibility to illness. The findings showed no significant difference in infection rates between individuals exposed to cold versus those in warm conditions, assuming both were exposed to the same viruses.

Final Thoughts: Myth or Reality?

The reality is likely somewhere in between. Cold temperatures alone do not directly cause illness, but they may contribute to conditions that make infections more likely—such as reduced mucosal immunity and increased indoor virus transmission. However, regular cold exposure may also have immune-boosting effects when done safely.

At Nebraska Health and Wellness Clinic, we emphasize that proper immune support—including adequate vitamin D, a balanced diet, hydration, and good respiratory hygiene—is far more critical than simply avoiding the cold. The best way to stay healthy is through immune resilience, not just warmth.

What are your thoughts? Have you noticed any personal trends with cold exposure and illness? Share your experiences below!