Every cell and organ in the body depends on water to function properly. Circulation, in particular, depends on adequate fluid intake because it affects how easily your blood moves through your vessels, blood pressure regulation, and how hard your heart has to work.
For those with a venous condition, peripheral artery disease (PAD), or another condition affecting blood flow, drinking the right amount of water daily is one of the most controllable habits to support healthy circulation.
In this guide, the vascular specialists at Michigan Vascular explain what happens to your blood when you’re dehydrated, how water intake can affect blood pressure, signs that you need to drink more water, and how to determine what “enough water” means if you are managing a vascular condition.
How Dehydration Thickens Your Blood
When you don’t drink enough water, a series of fluid shifts and hormonal responses occur that cause your body to pull water from its cells to maintain fluid in the bloodstream. As dehydration continues, plasma, the liquid portion of your blood, decreases, making your blood more concentrated. With less plasma, red blood cells occupy a larger share of the total blood volume.
That ratio is called hematocrit. When it rises, blood becomes viscous, meaning it is thicker and more resistant to flow. When blood viscosity gets too high, your heart has to work harder to push blood through your body. Research shows even a small one-unit increase in hematocrit can measurably increase blood thickness.
For someone with healthy circulation, a temporary increase in blood viscosity may have little effect. But if you have peripheral artery disease or chronic venous insufficiency, thicker blood adds to already-impaired circulation, making it harder for blood to flow efficiently. This can reduce oxygen and nutrients reaching your tissues, potentially worsening pain or cramping and slowing wound healing.
Researchers demonstrated this effect in a small study in which healthy volunteers sat for four hours in a dry environment under conditions similar to certain aspects of long-distance air travel. Their blood viscosity was measured throughout. Viscosity increased noticeably in participants who had no fluids beforehand, while prehydrating with an electrolyte drink kept viscosity close to baseline.
It’s important to note that the study didn’t say that dehydration alone will cause a blood clot, nor does it mean that drinking water can prevent a clot. The key takeaway is that dehydration can reduce blood flow, which may increase the risk of clot formation when other risk factors are present. For people with vascular disease, it illustrates why being diligent about hydration is especially important in situations that involve prolonged sitting in a dry environment.
To learn more about staying healthy while traveling with a vascular condition, read “Traveling With Vascular Disease: Tips for a Safe Trip.”
The Impact of Water Intake on Blood Pressure
Drinking enough water supports healthy blood pressure, but the relationship isn’t as simple as more water equals lower pressure. Hydration can affect blood pressure in different ways, potentially lowering it or raising it.
When you lose too much fluid without replacing it, blood volume decreases, which can lower blood pressure and leave you lightheaded, especially when standing up quickly. Your body also responds to excess fluid loss by releasing hormones and activating mechanisms that constrict blood vessels to maintain blood pressure. How much your pressure changes depends on the degree of dehydration and your body’s response.
On the other hand, drinking water can also temporarily raise blood pressure in some people. Research published in the American Heart Association journal Circulation found that water intake can activate the sympathetic nervous system, causing a short-term increase in blood pressure, particularly in older adults and people with certain autonomic conditions.
That doesn’t mean you should limit water intake if you have high blood pressure. A temporary increase in blood pressure after drinking water is part of normal blood pressure regulation in some people and is not the same as chronic high blood pressure. If you take blood pressure medication or have a vascular condition, talk with a vascular specialist about how much water is appropriate for you instead of making assumptions.
Another simple way to support healthy blood pressure is through slow, controlled breathing. To learn more, read “Breathing Exercises to Lower Your Blood Pressure.”
Signs Your Body Needs More Fluids
Most people think thirst is a sign to drink more water. It is, but it’s a late signal, not an early one. Some people, especially older adults, may not feel thirsty until they’re already dehydrated. Instead, pay attention to earlier signs your body may need more fluids, such as:
- Dark yellow urine or urinating less often than usual
- Fatigue or low energy without another obvious cause
- Dry mouth, dry skin, or headache
- Dizziness or lightheadedness, particularly when standing
- Muscle cramps
Leg cramping deserves special attention if you have venous disease or poor circulation in your legs and feet. Pain, especially with new or worsening swelling and heaviness, could be related to the vascular condition itself and shouldn’t automatically be treated as a hydration issue.
To learn more, read “Five Reasons You Should Never Ignore Leg Pain”.
How Much Water Should I Drink With Vascular Disease?
There isn’t a set number of ounces of water everyone should drink, including those with vascular disease. The CDC notes that daily water needs vary based on several factors, including activity level and individual health needs.
Daily Hydration Goals for Vascular Patients
The National Academies sets an adequate daily total water intake, from all beverages and food combined, at around 125 ounces for men and 91 ounces for women. Roughly 80% of that typically comes from what you drink, with the rest from food.
However, those suggestions are general guidelines for healthy adults. For someone managing a vascular condition, there are other things to keep in mind before assuming those numbers are enough to support healthy circulation.
- Use these guidelines as a starting point, not a strict target. Your doctor may adjust your water intake based on your specific diagnosis, medications, or other health conditions.
- Spread your intake across the day rather than drinking a large amount at once, particularly if you’re managing blood pressure.
- Adjust your hydration based on your circumstances. If you’re flying, exercising, spending time in hot or humid weather, or losing additional fluids from fever, vomiting, or diarrhea, you may need to drink more to replace the fluid your body is losing.
If you have a vascular condition and are unsure how much water you should drink each day, talk with your vascular specialist. Your individual hydration needs should account for your vascular health as well as any other medical conditions or medications that may affect how much fluid is appropriate for you.
What Are the Best Drinks for Heart Health?
Water should always be the first choice for supporting healthy circulation. According to the American Heart Association, it should be prioritized over other beverages. Unsweetened tea is another low-calorie alternative that has the added benefit of antioxidants linked to lower blood pressure.
Just as important as what to drink for heart health is what to limit. Alcohol and beverages with processed sugar should be used in moderation. Alcohol can negatively affect blood pressure and hydration, which can compound with a vascular condition, and sugary drinks are linked to higher triglycerides.
The AHA recommends no more than one alcoholic drink per day for women and two for men, and suggests capping sugary drinks to 25g per day for women and 37.5g a day for men. As a general rule, default to water and occasionally drink other beverages.
FAQ
Does drinking water thin your blood?
Not exactly. Water helps maintain your plasma volume, which keeps your blood at a normal viscosity rather than becoming concentrated. It’s more accurate to say water can help prevent blood from thickening than that it actively thins it.
Can you drink too much water if you have vascular disease?
It’s possible to overhydrate if you’re managing heart failure, kidney disease, or take certain blood pressure medications because they can affect how your body handles fluid. In these cases, don’t assume any particular amount of water is automatically safe for you. Ask your doctor or a vascular specialist what your personal upper limit is.
What’s the best time of day to drink water for circulation?
There isn’t a best time to drink water. Maintaining a steady fluid intake throughout the day to prevent thirst is what matters most for healthy blood flow. However, water may be especially important at two times of day: upon waking and before exercise.
Because the body goes several hours without fluids overnight, drinking water in the morning can help replace normal overnight fluid losses. Hydration is particularly important before exercise because starting activity already dehydrated can place additional strain on the cardiovascular system.
Support Your Circulation With Michigan Vascular Center
CDC data shows the average U.S. adult drinks only about 44 ounces of plain water a day, an amount that may not be enough on its own to meet daily hydration needs for many adults. Even mild dehydration can affect energy and mental clarity. For those with a vascular condition, it can also place additional strain on already impaired circulation.
Hydration is one of the simplest habits you can adopt to support your circulation, but it works best when paired with a personalized treatment plan. If you’re managing venous disease, PAD, or another circulation issue, the vascular specialists at Michigan Vascular Center can evaluate your vascular health and recommend treatment based on your specific condition and needs.
Schedule an appointment at one of our locations in Flint, Lapeer, and Saginaw to discuss your circulation and how hydration can fit into an overall plan for better vascular health.
Sources
Frontiers in Physiology – Blood Rheology: Key Parameters, Impact on Blood Flow
PubMed – Plasma volume and blood viscosity during 4 h sitting in a dry environment: effect of prehydration
CDC – Fast Facts: Data on Water Consumption
Mayo Clinic – Water: How much should you drink every day?
CDC – How much water should I drink each day?
CDC/NCHS – Daily Water Intake Among U.S. Men and Women, 2009–2012
American Heart Association (Circulation) – The Pressor Response to Water Drinking in Humans: A Sympathetic Reflex
American Heart Association (Circulation) – Low-Calorie Sweetened Beverages and Cardiometabolic Health: A Science Advisory
ACSM Position Stand – Exercise and Fluid Replacement
American Heart Association – Alcohol Use and Cardiovascular Disease
Nutrients (Li et al.) – Effects and Mechanisms of Tea Regulating Blood Pressure: Evidences and Promises
