Some of the most common causes of green skin are anemia and discoloration from wearing certain kinds of jewelry. In some cases, this condition can also be associated with severe health problems, such as multiple organ failure. It is also possible for green skin to simply be the result of bruising, though skin discolored in this way will generally be highly localized and exhibit a range of hues as it heals. Unless the discoloration is obviously localized to a bruise or linked to wearing jewelry, only a medical professional can properly diagnose the problem.
Hypochromic anemia, once commonly known as chlorosis, is one potential cause of green skin. This condition results in the red blood cells lacking the normal level of hemoglobin that normally gives them their red color. Consequently, people with hypochromic anemia sometimes exhibit a green pallor to their skin. Other symptoms of the condition can include shortness of breath, headaches, and a lack of appetite, while potential causes include B6 deficiency, low iron absorption, certain types of infections, or even lead poisoning.
Another potential cause of green skin is bruising, which generally involves internal bleeding into extracellular space within the skin. Bruises often initially appear reddish-blue or purple, which is due to the red pigmentation present in the blood's hemoglobin. This then breaks down into compounds like biliverdin, biliruben, and hemosiderin, each of which has a different color. Biliverdin in particular can have a greenish hue, and its presence in a bruise can cause the skin to appear green. A bruise often has many of these compounds present at any time during the healing process, so colors such as red, blue, green, yellow, and golden brown can all be present in a bruise.
Though anemia and bruising can cause greenish skin colors, they typically won't result in a very bright green hue. There have, however, been instances of skin taking on such a vibrant tone after multiple organ failure. In cases such as multiple organ failure, or sepsis, it may become possible for food dyes to be absorbed into the extracellular space. This can cause the skin to take on a bright blue or green tint. Food dyes are deemed safe for human consumption based partially on not being absorbable, but in cases where multiple organ failure or sepsis are present, they may be absorbed.
Green skin may also be caused by wearing certain jewelry. In particular, wearing accessories made of copper can have this effect. Perspiration from the skin may react with the copper, in effect corroding the surface of the jewelry and resulting in the same type of copper salts that cause copper-based items, like the U.S. Statue of Liberty, to appear green. This material may then transfer to the skin, causing it to have the same color.