Vasodilation is the medical term for when blood vessels in your body widen, allowing more blood to flow through them and lowering your blood pressure. This process happens normally in your body without you realizing it. It can be caused by things you eat or drink, and medications you take. Vasodilation can also be a symptom of certain diseases.


Vasodilation causes an affected blood vessel to widen, allowing more blood to flow through.
Vasodilation is the process that widens blood vessels.

What is vasodilation?

Vasodilation is the medical term for when blood vessels in your body widen, allowing more blood to flow through them and lowering your blood pressure. This is a normal process that happens in your body without you even realizing it. It’s also something that can be caused by things you eat or drink, and medications that you take. Vasodilation can also be a symptom of certain diseases.

How does vasodilation work?

Your blood has many different purposes in your body, including:

  • Carrying oxygen and nutrients.
  • Helping your body manage its temperature.

The blood vessels in your body aren’t just tubes that stay the same size all the time. Blood vessels also contain muscle, and that muscle controls just how wide or narrow your blood vessels are at any given time. When blood vessels get wider, that’s vasodilation. The opposite process, when blood vessels constrict and get narrower, is called vasoconstriction.


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Symptoms and Causes

What are some ways that vasodilation happens naturally?

Vasodilation happens commonly when you:

  • Blush or turn red: Ever notice how your face feels hot when you turn red out of embarrassment? That’s because of vasodilation of the blood vessels right under the surface of your skin (called capillaries), which increases blood flow to your face.
  • Step into a hot tub: When you enter the hot water, your body automatically tells capillaries to dilate. This is to help your body heat up more slowly. This is also why you should never stay in a hot tub too long, since this process may lower your blood pressure too much and cause you to pass out.
  • Exercise: When you’re physically active, your body needs more oxygen and nutrients delivered quickly to its cells (especially muscle cells). Widening your blood vessels allows more blood to flow through, meeting those needs.
  • Have an infection: Your body responds to infections by increasing blood flow to the affected area. This helps your body fight the infection and repair damage the infection caused.

Can anything I eat or drink cause vasodilation?

Yes, there are many things you can eat or drink that can cause vasodilation and, by extension, a decrease in blood pressure.

  • Foods that are rich in nitrates: Leafy greens like spinach and lettuce, radishes and bok choy are all rich in nitrates. Your body converts nitrates into nitric oxide, which is very effective at causing vasodilation.
  • Alcohol: When you drink alcohol, vasodilation is one of the things your body does right away. The effect is temporary and your blood pressure rebounds shortly after. Drinking too much also causes higher blood pressure, which is just one reason (of many) why healthcare providers recommend against drinking too much.


What medications cause vasodilation?

There’s a wide range of medications that cause vasodilation, either as their main purpose or as a side effect. Many types of blood pressure medications cause vasodilation because that’s their main purpose. Another common medication that causes vasodilation is nitroglycerin, which makes it useful in the treatment of heart attack and chest pain. Erectile dysfunction medications like sildenafil (Viagra®) also rely on vasodilation.

Management and Treatment

How is vasodilation treated?

If vasodilation has caused a large drop in blood pressure, this can be treated in multiple ways.

  • Fluid resuscitation: Giving IV fluids can help boost blood pressure.
  • Blood pressure-increasing medications: Two types of medications, vasoconstrictors and vasopressors, are treatments used to counter low blood pressure.


Can vasodilation be dangerous?

Yes, depending on what causes it, when it happens or how strong the effect is, vasodilation can have negative effects on your body. In extreme cases, vasodilation (and other symptoms associated with it) can be life-threatening.

Examples of life-threatening conditions with vasodilation as a factor include:

  • Severe allergic reactions: Also known as anaphylaxis (ana-fil-axis), this condition happens when the body’s immune system reacts so strongly that it can be deadly. During anaphylaxis, a person goes into shock, their blood pressure drops dangerously and their airways close off so they can’t breathe. Epinephrine, a common emergency rescue medication for anaphylaxis, is a strong vasoconstrictor. It reverses the drop in blood pressure and also has properties that help improve breathing and limit the immune reaction.
  • Septic shock: Sepsis happens when the body reacts so strongly to an infection that it is life-threatening. During septic shock, the most severe stage of the condition (which can be fatal), blood pressure drops because of widespread vasodilation. Giving intravenous (IV) fluids and blood pressure-raising medications are essential to saving a person’s life in this critical situation.

Living With

When should I call my doctor about vasodilation?

For the most part, vasodilation isn’t a cause for concern. In fact, since you can’t see it you may not notice that you have vasodilation. You can see its effects, however. Watch for conditions like fainting, which can be caused by a drop in blood pressure. If there’s a severe drop in blood pressure and shock, it could be life-threatening.

Symptoms of shock may include:

  • Altered mental state, including anxiety, agitation or confusion.
  • Blue coloration to lips and fingertips.
  • Feeling dizzy, lightheaded or fainting.
  • Skin that is cool, clammy or pale.
  • Profuse sweating.
  • Shallow or rapid breathing.
  • Fast, weak pulse.

If someone passes out and you suspect that they're in shock, you should do the following:

  • Stay calm and call 911. Don’t wait for symptoms to get worse. Every minute counts.
  • Make sure the person’s airway is clear.
  • Is the person breathing? Even if they are, check every five minutes until first responders arrive. Loosen any tight clothing that might restrict breathing.
  • Do they have a pulse? If not, immediately begin CPR and continue it until help arrives.
  • If the person doesn’t have an injury to their head, neck, legs or spine, place something underneath their feet so that their feet are at least 12 inches off the ground. This is called the shock position. Don’t elevate their head for any reason.
  • Perform first aid on other injuries if possible and appropriate.
  • Keep the person warm.
  • Do not give them anything to eat or drink.
  • If the person vomits or drools and you don’t suspect a head, neck or back injury, turn their head to the side to keep them from choking.

A note from Cleveland Clinic

Vasodilation is a natural process that increases blood flow and decreases blood pressure. Vasodilation is mostly beneficial, as it helps deliver oxygen and nutrients throughout your body. But, vasodilation can be harmful in some cases, leading to severe hypotension (low blood pressure). Be on the lookout for signs of shock, including altered mental state, clammy skin and shallow or rapid breathing. Call your healthcare provider if you or someone you know develops worrisome symptoms.

Medically Reviewed

Last reviewed on 06/23/2022.

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