As temperatures continue to fall across the country, the cold weather begins affecting the body in several ways—one of the most concerning being the thickening of blood. This condition becomes more noticeable in individuals who already suffer from heart disease, high blood pressure, diabetes, or high cholesterol.

Let’s understand why blood thickens in winter and whether this increases the risk of a heart attack.

Why does blood become thicker in winter?

According to Dr. Ajit Jain from the Cardiology Department of Rajiv Gandhi Hospital, the primary reason is the constriction of blood vessels during cold weather. When temperatures drop, the body tries to retain heat, which causes the blood vessels to narrow. As a result, blood circulation slows down.

This slower circulation increases the concentration of platelets and certain proteins in the blood, making it relatively thicker.

Dehydration also contributes. In winter, people often drink less water, which reduces the fluid content in the blood and further thickens it.

Common symptoms of thickened blood include:
• Tingling in hands and feet
• Cold fingers
• Dizziness or a heavy head
• Shortness of breath
• Fatigue

These symptoms become more pronounced in people with high blood pressure, diabetes, or cholesterol. Such individuals must take extra precautions.

Can thickened blood increase the risk of a heart attack?

Yes. Dr. Ajit Jain explains that thicker blood forces the heart to work harder to pump it throughout the body. At the same time, narrowed blood vessels due to cold weather slow blood flow even further. This increases the chances of blockages.

People with existing health conditions—such as high BP, diabetes, obesity, or high cholesterol—face a higher risk. Cold weather puts additional strain on the heart’s arteries and also increases the likelihood of sudden blood clots. This combination significantly raises the risk of heart attack during winter.

How to prevent this winter risk?

• Drink plenty of water daily
• Do light exercise or walk regularly
• Keep yourself warm when going outdoors
• Avoid oily and high-fat foods
• Heart, BP, and diabetes patients must take their medication consistently
• Avoid sudden exposure to very cold temperatures
• Maintain controlled salt intake

Staying warm, hydrated, and active can help reduce winter-related heart risks and keep blood circulation healthy.