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The blood inside your veins is dark red. Many people wonder why veins look green or blue, instead of taking on a blood-red hue.

Veins are types of blood vessels. The other blood vessel types are capillaries and arteries. Blood vessels help transport blood and nutrients throughout your body.

The job of most veins is to carry oxygen-depleted blood from bodily tissues back to your heart. Your pulmonary artery brings your blood to your lungs, where it receives a fresh supply of oxygen. Your arteries then carry the oxygenated blood to your tissues and organs.

In this article we’ll explain why veins can look green or blue, particularly on lighter-colored skin. We’ll also go into detail about vein symptoms that require medical attention.

There are three types of veins:

Superficial veins are the type you can see. They may look green instead of red because the color green has a shorter wavelength than the color red. They may also look blue or blueish-green because blue has a shorter wavelength than red.

According to the National Aeronautics and Space Administration (NASA), the electromagnetic spectrum contains wavelengths, or visible light that your eye can see. The colors of visible light range from red to violet in this order:

Red –> Orange –> Yellow –> Green –> Blue –> Violet

According to the New Zealand Government, red has the:

  • longest wavelength
  • lowest frequency
  • least amount of energy

Violet has the most energy, with green and blue near the middle. When light penetrates skin, it illuminates your veins. The green and blue wavelengths in the light have enough energy and speed to reflect back, so those colors are visible. Red light doesn’t have enough energy to make it through skin.

Superficial green veins may be most visible on specific parts of your body and face, such as:

  • backs of hands
  • shins
  • thighs
  • abdomen
  • chest
  • forehead
  • neck

Green and blue veins can also be seen where your skin is thin. Skin can become thinner and less elastic with age, making veins appear more prominent. No matter what your age, the less fat you have, the more your veins may show as well.

Other reasons why veins may be more visible

Here are some other reasons why veins may appear more prominently:

  • Genetics can play a role in how visible your veins appear. For example, if your mother or father have noticeable veins, you may also.
  • Emotion can also have an effect. If you’re angry and yelling, or laughing uproariously, an increase in pressure may make your veins expand and bulge. This may be most likely to occur on your forehead, temples, and neck. Sneezing can also have this effect.
  • Exercising can also raise blood pressure, making veins more prominent.
  • Heat and hot weather can cause veins to expand and dilate, making them more visible.

Visible green veins are usually nothing to be concerned about, unless they’re accompanied by other symptoms such as:

Medical conditions earmarked by visible veins include:

Varicose veins

Varicose veins are caused by a malfunction in your one-way valves that stop blood from flowing through your veins backward.

Varicose veins often appear on your lower legs. Since they’re engorged with blood, varicose veins may look enlarged and swollen. They may look like zigzags, and take on one of the following colors:

  • blue
  • red
  • purple

Varicose veins can be painful. They may also make your legs feel:

  • heavy
  • itchy
  • tired

Pregnant women and women more than 50 years old may be more likely to get varicose veins. If you have obesity, you may also be prone to this condition.

Spider veins (telangiectasia)

Spider veins are not green. They appear as tiny, threadlike red or discolored lines under your skin, in areas such as your:

  • nose
  • cheeks
  • fingers

Spider veins sometimes hurt or itch. They may indicate a serious underlying condition, such as alcohol use disorder. In many instances they’re caused by aging blood vessels or by behaviors such as sitting or standing for long periods of time. Pregnancy can also cause spider veins.

Superficial thrombophlebitis

Superficial thrombophlebitis is an inflammatory, short-term condition caused by a blood clot under your skin.

Symptoms include:

  • redness or discoloration
  • warmth
  • hardening of a vein
  • darkening of your skin
  • pain
  • inflammation

Superficial thrombophlebitis is often caused by insertion of an intravenous (IV) needle. It may also result from varicose veins.

Since it occasionally leads to a serious condition called deep vein thrombosis, you should always call a doctor if you suspect you have superficial thrombophlebitis.

Green veins are superficial veins located near the surface of your skin. They appear green instead of red because green has a shorter wavelength than red.

You’re more likely to see green or blueish-colored veins if your skin is a lighter color. If you have darker skin, it can be harder to see the color of your veins.

Green veins are not indicative of a serious condition unless they’re accompanied by other symptoms, such as:

  • swelling
  • inflammation
  • pain

If you’re experiencing any of the above symptoms, talk with a doctor. They can diagnose and recommend treatment for any vein-related conditions you may have.