What is Vasodilatation?

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  • Written By: Daniel Liden
  • Edited By: Bronwyn Harris
  • Last Modified Date: 19 October 2016
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Vasodilatation, also referred to as vasodilation, is the widening of blood vessels that occurs when the muscles in the walls of such vessels become relaxed. Vasodilatation can occur for many different reasons, from drugs to exercise. It is the opposite of vasoconstriction, by which the blood vessels constrict and narrow. The dilation of blood vessels leads to a decrease in blood pressure, while the constriction of blood vessels leads to an increase. Either process can be restricted to a single organ or organ system, or it can happen throughout the entire body.

Anything that leads to vasodilatation is known as a vasodilator. Vasodilators can be natural or artificial and they can be internal or external. Some medicines are vasodilators; these are usually used to control high blood pressure. Dilation and constriction of blood vessels occurs almost nonstop based on the amount of blood that is needed in any given part of the body at any given moment. It can also occur because of various hormones or signals in the nervous system.


Drugs that induce this condition are commonly used to treat several different conditions. They are frequently used to treat hypertension, a condition in which one persistently has very high blood pressure. They can also be used to treat heart conditions such as angina and congestive heart failure by maintaining a lower, healthier blood pressure. Maintaining a lower blood pressure through the use of medications that lead to vasodilatation can reduce the risk of many different heart-related illnesses in those with abnormally high blood pressure.

In some warm-blooded animals, this process is one method by which a consistent, healthy temperature is maintained. When the external environment is very warm, some of the blood vessels of such animals will dilate and redirect warm blood to the skin or extremities of the animals. When the warm blood is close to the skin, heat can escape into the environment, cooling the animal down to better temperatures. When the outside environment is cold, vasoconstriction can occur and have the opposite effect, keeping the warm blood around the animal's vital organs.

There are many different things inside and outside of the human body that can cause vasodilatation. Inside, histamine and lactic acid are among the many different chemicals that can cause blood vessels to dilate. Exercise and muscle work can also cause the dilation of some blood vessels. External causes can be as simple as an absence of excessive amount of environmental noise and light. Tetrahydrocannabinol (THC), the active component of marijuana, also causes mild vasodilatation and leads to a reddening of the eyes of marijuana users.


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Post 3

@fify-- I'm not an expert so I can't say for sure, but I do know that chronic fatigue syndrome is caused by hypoxia (cells and tissues not getting enough oxygen). And hypoxia leads to (or should lead to) vasodilatation by definition.

Vasodilatation in this situation is the body's control mechanism to hypoxia. By dilating the blood vessels, it aims to reach more oxygen to the cells and tissues.

I think there might be a link between chronic fatigue syndrome and vasodilatation if the vasodilatation mechanism in the body is not working correctly. Rarely hypoxia can cause vasoconstiction instead of vasodilatation and there are several disorders caused by this.

So technically, a dysfunction of the vasodilatation system in the body can and will lead to fatigue, exhaustion and pain. In my opinion, it can lead to chronic fatigue syndrome but don't take my word for it. Experts on this subject can answer your question more accurately.

Post 2

Does anyone know about the connection between chronic fatigue syndrome (CFS) and vasodilatation?

I've been dealing with CFS for more than five years and have not been able to figure out the cause or completely treat it. Recently, my doctor mentioned that CFS might be due to blood vessels not dilating enough and the lack blood flow to all areas of the body contributing to or causing CFS.

I don't think anything is 100% proven but CFS responds well to a treatment with acetylcholine which is a neurotransmitter that causes vasodilatation. So it does seem to support the idea that this condition is due to lack of vasodilatation or too much vasoconstriction.

Any thoughts on this?

Post 1

I think vasodilatation is a great mechanism because it can be used to treat various conditions.

Like the article said, there are medications that cause vasodilatation and these help reduce blood pressure. My mom has had high blood pressure for the last fifteen years and she's been on vasodilatating medications since. These help keep her blood pressure in control.

I don't take any medications but I do use heat therapy because I experience circulation problems in winter from the cold. I use heat pads on my feet and legs throughout winter. Heat causes peripheral vasodilatation (when blood vessels in the limbs dilate) and improved circulation to that area.

This is also why the blood vessels on our foot look especially large in the summer. When the weather is hot, they dilate, when it's cold, they constrict. It's also why I experience coldness and color changes in my legs and feet in winter.

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