Blue veins under the skin of the hands are often visible and usually harmless. In many cases, they result from natural causes like pale or thin skin. “White skin, thin skin are both reasons why you have blue veins but I do not.” Older adults and people with low body fat may notice more prominent veins.

Athletes or those doing heavy labor may also see bulging veins during activity, which “gradually subside when the activity stops.” Pregnant women can experience this too, due to increased blood flow.

However, sometimes visible veins can point to health problems.