Excessive exercise, aging, hot weather, tight clothing, genetics, sun exposure, and being overweight are common causes. Bulging veins can be innocuous in certain situations, but it’s best to see a doctor if they show signs of discoloration.

When blood pools in weak or damaged veins instead of returning to the heart smoothly, veins bulge. Varicose veins—swollen, twisted veins that usually appear on the legs but can also appear on the arms—are frequently the result of this.