An Instagram post by Dr Yokesh Arul claims that winter temperatures sharply raise heart attack risk by causing blood vessels to constrict, blood to “thicken,” and the heart’s workload to increase, especially in people with diabetes, hypertension and high cholesterol.

FACT:

Experts agree that cold weather can raise blood pressure and strain the heart through vasoconstriction, particularly in people with existing heart conditions, but they note that claims of blood ‘thickening’ to dangerous levels are overstated. Evidence shows the increased risk is real but mainly affects those with underlying cardiovascular issues, not healthy individuals.

As the winter months roll by, a common concern a lot of people have is how the cold temperatures affect their health. A concern we come across online regularly is about the alleged increased susceptibility to heart attacks during cold months. This year too, a widely shared Instagram reel by Dr Yokesh Arul, who says he is a doctor and health content creator, asks viewers to take care of their parents’ health, as winter temperatures significantly increase the risk of heart attacks. He warns that the risk is especially high for people with diabetes, hypertension and high cholesterol.

In the post — which has drawn over 10,000 interactions and multiple user endorsements — he claims that exposure to cold weather causes blood vessels to constrict, blood to “thicken,” and the heart’s workload to rise, making individuals more susceptible to cardiac events.

In his caption, Arul urges people to “keep parents warm, insulated, consistent on medicines, and avoid heavy oily snacks this season,” framing this as a necessary precaution against the heightened winter risk. The post suggests that these temperature-driven physiological changes can increase susceptibility to heart attacks, particularly among older adults and those with underlying lifestyle diseases.

Though the video does not cite any scientific study, it presents the mechanism — vasoconstriction, increased blood viscosity and elevated cardiac workload — as an established fact, and asserts that cold exposure itself is a seasonal cardiac risk factor. The claim has gained traction among followers, reflected in numerous comments thanking him for “awareness,” sharing personal concerns, and asking further medical questions.

What are the facts?

First Check has repeatedly investigated such claims related to whether heart attacks are more prevalent on certain days of the week, particular time of the day, or certain seasons. In fact, research from the United States had found that more people die of heart attacks during the Christmas-New Year holiday season, or the last two weeks of December, which are the winter months.

“Cardiac mortality for individuals who are dead on arrival, die in the emergency department, or die as outpatients peaks at Christmas and again at New Year’s,” according to the study. However, the researchers claimed that there are “multiple explanations for this association, including the possibility that holiday-induced delays in seeking treatment play a role in producing the twin holiday spikes.”

In India, medical experts broadly support the view that the risk of heart attacks do increase during winter. In fact, multiple leading hospitals in India have also spoken of spikes in heart attacks during winter months. “The chances of heart attacks go up by nearly 33 per cent during winter,” Dr Bipin Kumar Dubey, the HOD-Cardiology & Principal Director – Interventional Cardiology at Max Hospital in Dwarka, New Delhi, wrote.

“Further, patients afflicted with angina need to be particularly careful as the cold weather can cause coronary artery spasms, leading to heart attack. Certain individuals are at a higher risk of getting a heart attack during cold weather, including elderly people, those who have had a prior history of heart attacks, coronary heart diseases, heart failure, high blood pressure, high cholesterol, diabetes, smoking and a sedentary lifestyle,” they added.

Bangalore-based Kauvery Hospital has also said that “the risk of heart disease in winter rises substantially due to the above factors”, which include higher blood pressure owing to lower temperatures, cold-induced plaque ruptures, exertion and seasonal infections.

The Medanta Medical Team reiterates these claims and says that this is because of “several factors, including cold weather, changes in air pressure, and lack of physical activity.” “Cold weather can constrict blood vessels, making the heart work harder and increasing the risk of heart-related problems,” it added.

However, experts also caution against overstating some of the physiological effects circulating on social media. “There are also other factors which affect blood pressure, such as lack of Vitamin D and a more sedentary lifestyle that sets in during the winter months. We see people go out less, get less amount of sun exposure,” Dr Suneela Garg, a Community Medicine professional, had told us earlier. “The pollution also goes up during these months, leading to people not stepping outside. So, all these factors come together to bring about an increase in blood pressure.”

Dr Shiv Kumar Choudhary, Cardiovascular and Thoracic Surgeon at Fortis Hospital, New Delhi, had also said that while cold weather can indeed trigger blood vessel constriction – the mechanism known as vasoconstriction – it is inaccurate to suggest that blood becomes “thicker” to the point of causing sudden cardiac events in otherwise healthy people.

“Cold weather can increase the risk of heart attacks, particularly in people with pre-existing heart conditions, because of vessel constriction and changes in circulation. However, for healthy individuals, these risks are minimal,” he said.

Research supports this nuanced view. A study published in the Journal of the American College of Cardiology reported that exposure to cold temperatures can raise blood pressure and increase cardiovascular strain, but the effect is significantly more pronounced in people with pre-existing heart disease.