Understanding the Vasodilation Process
Ways to enhance blood flow
Medically reviewed by Christopher Lee, MDMedically reviewed by Christopher Lee, MD
Vasodilation is a function within the circulatory system that occurs when the smooth muscles in the blood vessels relax, allowing the blood vessels to widen or dilate. This increases blood flow to areas lacking nutrients or oxygen. Vasodilation can occur naturally when the body signals a need for nutrients or oxygen or with vasodilator medications, such as calcium channel blockers or (angiotensin-converting enzyme) ACE inhibitors, to treat high blood pressure.
Illustration by Julie Bang for Verywell Health
Vasodilation Explained in Simple Terms
"Vaso" comes from a Latin word meaning vessel, and "dilation" means to widen, hence vasodilation. Understanding the basic physiology of the circulatory system may help provide context as to how vasodilation fits into the "bigger picture."
The Circulatory System
The circulatory system is responsible for delivering oxygen and nutrients throughout the body via your blood. It includes the following:
Heart: Pumps blood
Blood vessels: Carry blood throughout the body
Arteries: Carry blood away from the heart
Veins: Carry blood back to the heart
Vasodilation and vasoconstriction (narrowing blood vessels) help move blood through your body's extensive network of blood vessels. Think of your heart as the pump that powers blood flow and your blood vessels as the pipes that carry the blood. Vasodilation affects your blood vessels.
Movement—specifically contraction and dilation—of the smooth muscles in your blood vessels plays an essential role in circulating blood throughout the body. When vasodilation occurs, blood vessels widen to increase blood flow. When vasoconstriction occurs, the vessels narrow, decreasing blood flow and increasing blood pressure.
Benefits of Vasodilation
When blood needs to move more quickly or specific body areas require more blood volume, vasodilation helps increase blood flow. Without the resistance of a narrower blood vessel, vasodilation helps deliver oxygen-rich blood to the tissues.
When Vasodilation Happens
Vasodilation can occur in any body area, depending on the need for oxygen and nutrients. Your body sends electrical and chemical signals to trigger vasodilation.
Types of Vasodilators
In addition to the internal mechanical and chemical triggers that cause vasodilation, other substances can replicate or enhance the opening of blood vessels.
Some medications a healthcare provider may prescribe to help dilate your blood vessels include:
Direct-acting arterial vasodilators like hydralazine
Indirect arterial vasodilators like calcium channel blockers or beta-blockers
Conditions That Change Vasodilation
High blood pressure (hypertension) affects vasodilation. If you've been diagnosed with hypertension, your blood vessels have narrowed for various reasons, and blood flow can become restricted. You may need medications that increase your natural vasodilation if you have high blood pressure. Vasodilator medications relax the smooth muscles to open the vessels and let more blood flow through.
Emergency Vasodilation Complications
Too little vasodilation can increase blood pressure and restrict blood flow, but too much vasodilation can drop your blood pressure dangerously low.
Vasodilatory shock is a condition that can occur with severe illness. Anaphylaxis, severe inflammatory reactions, infections, and other critical illnesses can suddenly cause blood vessels to relax. This sudden change can lead to circulatory shock and cause profound hypotension (low blood pressure), which is a medical emergency.
If your body is in a state of shock that results in low blood pressure from too much vasodilation, you will likely need treatment in an intensive care unit with medications called vasopressors. These medications cause vasoconstriction and help to increase resistance in your blood vessels and raise your blood pressure.
How to Improve Vasodilation
Your body naturally dilates and constricts your blood vessels to meet the demands of your tissues, but over time, these body responses can become less effective. Eating a balanced diet, monitoring your cholesterol, maintaining healthy blood pressure, and getting regular exercise can help you ward off conditions that can strain your circulatory system.
If you notice an increase in your blood pressure that does not yet require prescription medications, your healthcare provider may recommend diet and lifestyle changes. Some natural substances and supplements also have a vasodilatory effect.
These substances have a similar effect to vasodilator medications, so talk to your healthcare provider before using them. Too much vasodilation could result in dangerously low blood pressure.
Some examples of natural vasodilators include:
Glycine propionyl-L-carnitine (GPLC)
Nitric oxide
These substances and others can have a vasodilatory effect, but controlling the exact amount of vasodilation can be challenging. If you have severely high blood pressure, you may still need to take prescription medications, and combining these supplements with your medications may not be safe. Always talk to a healthcare provider before taking any new supplements.
Summary
Vasodilation is a vital function that allows blood vessels to relax, increase blood flow, and lower blood pressure. It can happen naturally, through certain medications, or by various supplements or exercise. If you have high blood pressure, your healthcare provider may prescribe medications that increase vasodilation. Do not attempt to treat your high or low blood pressure at home without consulting your primary healthcare provider. Always check before starting any new supplements.
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