I am a young female 25 years of age, healthy and physically active. In the past few months I have noticed very dark, large green veins on my arms and one or two on my chest. The only medication I started to take were Iron supplements during my menstruation. I am very curious about this, please help me understand it. Thank you
Prominent veins in hand is a common feature.  Please don't worry. Normally this can be found in fair complexion person. If the fat layer below skin is lost it can be well visible, mostly found in your dominant hand(the hand you use most). Similarly, the veins over chest is visible in females due to hormonal effect. As for example during pregnancy. It is quite normal. And not an effect of iron tablets. No treatment is required at present. But if you find progressive swelling of your hand or some skin changes you may need to consult a physician for examination. But that, I think, could hardly happen as you are physically fit and active. So no need to worry.  Wish you good health.