Staying Hydrated and Stroke Prevention: What You Need to Know

As temperatures rise and summer activities ramp up, it's important to remember that heat and hydration are more than comfort concerns — they can directly impact serious health conditions, including the risk of stroke.

According to Felipe De Los Rios La Rosa, M.D., stroke program director at Baptist Health Miami Neuroscience Institute, dehydration during hot weather can significantly raise the risk of experiencing a stroke, especially for those already at risk.

Link Between Dehydration and Stroke

Hear from Dr. De Los Rios in a new Instagram reel about dehydration and stroke.

Dr. De Los Rios emphasizes that "as summer approaches, we have to be careful with dehydration, which can increase the risk of stroke in several ways." Stroke, which occurs when the blood supply to the brain is interrupted or reduced, can be influenced by changes in the body’s fluid balance. Dehydration can contribute to this in multiple harmful ways.

"Blood is viscous in general," Dr. De Los Rios explains, "so if you're dehydrated, it will become more dense and the probability of forming clots will increase." Thicker, more viscous blood increases the likelihood that clots may form, potentially blocking critical arteries in the brain and triggering a stroke.

But it’s not just about the formation of clots. Dehydration also affects blood pressure and circulation. "Dehydration can lower your blood pressure and affect the blood flow to the area of the brain," Dr. De Los Rios says. Inadequate blood flow can starve the brain of oxygen and nutrients, compounding stroke risk and severity.

Moreover, for those who are already experiencing a stroke or are in the early stages of one, dehydration may worsen the outcome. "If there's already a stroke happening, it can make the stroke be more severe. So, dehydration should be avoided, especially during the summer months," he adds.

Ischemic Stroke vs. Heat Stroke

Ischemic stroke is the most common type of stroke where blood flow to the brain is blocked, usually by a clot, leading to tissue damage. A condition commonly known as “heat stroke” is a different and distinct medical emergency that occurs when the body's core temperature rises to 104°F (40°C) or higher due to prolonged exposure to extreme heat. Heat stroke can lead to an ischemic stroke in individuals with certain underlying health issues.

Who Is Most at Risk?

While everyone should be mindful of hydration, certain individuals are more vulnerable to the effects of dehydration when it comes to ischemic stroke risk. These are typically people with existing conditions that already predispose them to vascular issues.

"Those that are more vulnerable to dehydration-related strokes will be those that already have risk for developing strokes," says Dr. De Los Rios. He points to individuals with blood clots to the brain caused by atherosclerosis — a condition in which the arteries narrow due to fatty deposits — as being particularly at risk.

Atherosclerosis reduces the diameter of blood vessels, making it easier for clots to obstruct blood flow. When compounded by dehydration, the likelihood of a blockage increases, turning an already dangerous condition into a potentially life-threatening one.

The Importance of Hydration in Stroke Prevention

Proper hydration is not just a good health habit — it may play a direct role in reducing stroke incidence and severity. “Staying hydrated will improve the chances of both staying healthy and avoiding a stroke,” Dr. De Los Rios notes. Adequate fluid intake helps maintain optimal blood consistency and supports steady blood pressure and brain perfusion.

Even in cases where a stroke does occur, hydration can still have a protective effect. “If a stroke occurs, staying hydrated will probably make it less severe,” he adds. This highlights the dual value of hydration both as a preventative measure and as a potentially mitigating factor if a stroke happens.

Practical Hydration Tips for the Summer

As the mercury climbs, so too should our awareness of the need for regular fluid intake. Here are some practical tips for staying hydrated:

• Drink water consistently throughout the day, not just when you feel thirsty. Thirst is a late signal that your body is already on its way to dehydration.
• Increase fluid intake with outdoor activity or exercise, particularly in hot or humid conditions.
• Monitor the color of your urine — light yellow usually indicates adequate hydration.
• Avoid excessive alcohol and caffeine, which can contribute to dehydration.
• Incorporate hydrating foods, such as fruits (like watermelon, oranges, and strawberries) and vegetables (like cucumbers and lettuce).

Staying hydrated should be seen not just as a lifestyle tip, but as an essential part of stroke prevention — especially for individuals with existing cardiovascular risk factors. Dr. De Los Rios’s insights serve as a timely reminder that something as simple as drinking enough water can make a significant difference in reducing health risks.

Explore Stroke Services at Baptist Health Brain & Spine Care.