Being cold doesn’t make us sick. It is a myth that has been propagated for a long time. But then why are diseases more common in winter?
We grew up hearing that time makes us sick. Going outside without a coat, breathing cold air, sleeping in a cold room, being rained on or snowed in, or simply feeling cold are often cited as causes of colds or flu.
This belief rings true for many people because the disease often appears after exposure to cold.
However, modern research shows that link between cold weather and illness is more complex than the idea that cold directly causes illness.
The truth is that the Cold temperatures alone do not cause infections.
Instead, they influence a combination of biological, environmental and social factors that make people more vulnerable to respiratory illnesses, especially during the winter months.
Colds and flu are caused by viruses, not cold air.
Viruses like rhinoviruswhich cause the common cold, and flu viruses spread from person to person through respiratory droplets or physical contact, regardless of the outside temperature.
That said, rates of respiratory infections rise consistently during colder seasons in many parts of the world — a pattern that has been observed globally.
This seasonal pattern is partly due to how cold temperatures and low humidity affect viruses in the environment.
Research shows that many respiratory viruses, including flu viruses and coronaviruses, survive longer and remain infectious for prolonged periods in cold, dry conditions.
Dry air also causes tiny droplets released when people breathe, talk, cough or sneeze to quickly evaporate. This creates smaller particles that remain suspended in the air for longer, making others more likely to inhale them. As a result, the Cold, dry air helps viruses persist in the environment and increases their chances of reaching someone else’s respiratory system.
O Cold air also affects how the body defends itself against infections. Breathing cold air lowers the temperature inside the nose and airways, which can trigger vasoconstriction. Vasoconstriction means the narrowing of blood vessels, which reduces blood flow to tissues.
In the lining of the nose and airways, this reduction in blood flow may weaken local immune responses which normally help detect and eliminate viruses before they cause infection.
Exposure to cold and stress associated with cold can also interfere with normal airway function, particularly in people with sensitive respiratory systems. Together, These effects can suppress the body’s first lines of defense in the nose and throat.
In other words, cold air does not create viruses, but can make it easier for viruses to take hold once exposure has occurred.
As seasonal changes in human behavior and environments Interiors also play an important role.
Cold weather encourages people to spend more time indoors, often in close contact with others. Overcrowded spaces with poor ventilation allow virus-containing droplets to accumulate in the air, making person-to-person transmission more likely.
During winter, less exposure to sunlight leads to a lower production of vitamin D in the skin. Vitamin D is involved in regulating immune function, and low levels are associated with weaker immune responses. Indoor heating, although essential for comfort, dries the air.
O Dry air can dry out the lining of your nose and throatreducing the effectiveness of mucus. Mucus normally traps viruses and helps remove them from the airways, in a process known as mucociliary clearance. When this system is compromised, viruses find it easier to infect cells.
Cold weather can be particularly challenging for people with pre-existing respiratory illnesses, such as asthma or allergic rhinitis. Epidemiological studies show that cold conditions can aggravate symptoms and increase functional limitation in these people. This can intensify the effects of respiratory infections when they occur.
Taken together, the evidence paints a clear picture of what cold weather does and doesn’t do.
What the evidence doesn’t support is the idea that simply being cold, like going outside without a coat, directly causes a cold or flu. Instead, cold weather acts as a risk amplifier. It creates conditions that help viruses survive, spread and overcome the body’s defenses.
