Daijiworld Media Network – New Delhi
New Delhi, Oct 29: As temperatures begin to drop across India, doctors are warning that the risk of stroke rises significantly during winter, with studies showing a clear connection between cold weather and increased cardiovascular strain. Researchers have found that when average temperatures fall below 13°C, cases of ischemic stroke — caused by blocked blood flow to the brain — rise sharply.
According to Dr Manoj Khanal, Director, Neurosciences, Max Super Speciality Hospital, Shalimar Bagh, cold conditions affect the body in multiple ways — from elevating blood pressure and thickening blood to promoting clot formation. “Compared with warmer temperatures, the low-temperature group shows a significantly higher proportion of patients with hypertension and large artery atherosclerotic stroke,” he explained.
With World Stroke Day 2025 focusing on prevention, experts are calling for greater awareness of how seasonal changes impact brain health, especially in northern India, where winter temperatures can dip drastically and trigger stress responses that heighten the risk of both ischemic and haemorrhagic strokes.
Cold weather causes blood vessels to constrict, increasing blood pressure and placing extra strain on the cardiovascular system. The World Health Organization (WHO) identifies hypertension as the most significant modifiable stroke risk factor, and doctors report more uncontrolled cases during winter months.
Low temperatures also make blood thicker and more prone to clotting, a major cause of ischemic stroke. A 2023 Journal of the American Heart Association (JAHA) study found that cold conditions increase blood viscosity and platelet reactivity, which elevate clot formation risks.
Another major concern is reduced physical activity during winter. People tend to stay indoors, move less and consume calorie-heavy foods, leading to weight gain and higher cholesterol. “Even moderate activity, such as brisk walking for 30 minutes a day, can reduce stroke risk by up to 25%,” said Dr Khanal, citing data from the American Stroke Association.
Dehydration, often overlooked in cold weather, also contributes to stroke risk. People feel less thirsty in winter, making the blood more viscous and prone to clotting. A 2021 European Journal of Preventive Cardiology study found that dehydration increases haemoconcentration and platelet aggregation — both key factors in stroke formation.
Dr Khanal also cautioned against sudden overexertion in the cold, such as shovelling snow or heavy outdoor work, which can sharply raise heart rate and blood pressure. The National Institute of Neurological Disorders and Stroke (NINDS) has reported that such exertion can trigger strokes in people with underlying heart disease.
Adding to the seasonal risk are flu and respiratory infections, which are common in winter. “Inflammation caused by infections can damage blood vessels and worsen hypertension, leading to higher stroke risk,” Dr Khanal said. Research published in Neurology (2022) found that respiratory infections can triple stroke risk within three days of infection.
Experts say prevention during winter demands extra vigilance — keeping warm to avoid vessel constriction, staying active through moderate indoor exercise, staying hydrated, and managing co-morbidities like blood pressure, cholesterol and diabetes. They also advise avoiding alcohol and smoking, and getting vaccinated against flu to reduce infection-related inflammation.
A 2024 BMJ study found that flu vaccination lowered stroke risk by 12% among adults over 50.
Dr Khanal cautioned that cold weather can trigger sudden symptoms such as loss of balance, facial drooping, numbness in limbs or slurred speech. “If you experience these symptoms, rush to the nearest stroke-ready hospital. Early medical intervention can save lives and improve recovery,” he advised.
Medical experts stress that while both hot and cold extremes can raise stroke risk, the impact of cold weather tends to last longer, underscoring the importance of proactive care during winter.