The exact colour spectra is determined by the relative levels of oxygenated iron (HbO) and carbon dioxide in the blood. High levels of oxygen reflect red, and high levels of carbon dioxide reflect blue, which, when mixed with the yellowish colour of fat and or the skin, end up looking green.

Are green veins bad?

Green veins aren't indicative of a serious condition unless they're accompanied by other symptoms, such as: swelling. inflammation. pain.

Why do my veins get green?

Varicose veins occur when the valves within the veins stop working properly and allow blood to backflow. The blood pools in the area below the affected valve causing the vein to enlarge and stretch. Varicose veins appear under the skin as bluish-green lines, which may bulge out or appear twisted and contorted.