Can cold weather make you sick?

It's a common misconception that being physically cold means you'll get a cold, perhaps because respiratory infections usually soar during the winter months. While frostier weather can make us more susceptible to infections — for instance, by lowering immune defenses against respiratory viruses — the frigid conditions don't actually cause the illness in the first place.

But there are various other conditions that are triggered by chillier temperatures. One example is hypothermia, which is caused by a dangerous drop in core body temperature.

Normally, the temperature of the human body is tightly regulated at around 98.6 degrees Fahrenheit (37 degrees Celsius), give or take a degree or so. This keeps all of the normal physiological processes in the body ticking along.

Related: How does a person freeze to death?

However, if someone is exposed to extremely cold temperatures, the body may not be able to produce heat as fast as it loses it, causing a person's core body temperature to plummet. If an individual's body temperature falls below 95 F (35 C), they can develop hypothermia.

Hypothermia causes an array of symptoms, including shivering; pale, cold and dry skin; slurred speech; and slow breathing. If left untreated, hypothermia can result in organ malfunction and failure, which may eventually lead to death. Each year, between 700 and 1,500 people die from hypothermia in the U.S.

Exposure to temperatures below 32 F (0 C), especially for prolonged periods, can also trigger a skin condition known as frostbite. Children, unhoused people and older adults are particularly at risk from this condition. Frostbite typically occurs in the extremities of the body, such as the fingers, toes, nose and ears. Intense cold causes the water within tissues to freeze, restricting the flow of blood and potentially resulting in tissue death. Consequently, a patient's skin may turn purple or blue, and in severe cases, the dead tissue may have to be removed via surgery or amputation.

Another condition that is caused by cold weather and affects blood flow is Reynaud's syndrome, Dr. Rachel Amdur, an assistant professor of medicine at Northwestern University, told Live Science.

Reynaud's disease causes blood vessels to constrict — particularly those in the extremities, such as the fingers and toes, turning them white or blue. The condition is triggered by the cold in people who are predisposed to having the syndrome, Amdur said. This includes individuals with a family history of the condition, people with certain other diseases, such as rheumatoid arthritis and lupus, or those who are taking certain medications, including some used to treat high blood pressure or migraines.

Further examples of illnesses that are driven by cold weather include trench foot — a type of foot damage caused by prolonged exposure to cold, damp conditions; chilblains, in which itchy swellings appear on the skin; and cold urticaria, in which the skin forms hives.

Cold weather can also aggravate other illnesses, such as eczema and respiratory conditions like asthma or chronic obstructive pulmonary disorder (COPD), Amdur said. Furthermore, heart attacks are more common in the winter — likely because people's blood vessels constrict, raising their blood pressure and forcing the heart to work harder than usual.