Cold weather has long been blamed for making people sick, but science paints a more complicated picture. Research shows that chilly temperatures do not directly cause colds or flu, even though illness often seems to follow time spent in the cold.
Instead, winter conditions create an environment where viruses spread more easily and the body’s defenses are less effective. Cold, dry air allows respiratory viruses to survive longer and stay airborne, while breathing in cold air can reduce blood flow inside the nose and airways, weakening local immune responses that normally help block infection.
Seasonal habits also play a role, as people spend more time indoors in close contact with others, often in poorly ventilated spaces. Together, these factors turn cold weather into a risk amplifier rather than a cause, helping explain why respiratory illnesses peak in winter while dispelling the idea that simply feeling cold makes you sick.
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