I am 51 and post-menopausal. I thought it would be okay once to take a multi-vitamin which I thought did not have iron it but found out it did. I took it for a few days anyway and started experiencing bad after taste that went through the whole day as well as sticky gray stools.
I researched how much iron I should get and eight milligrams daily from supplements (they figure you get the rest from food) is the maximum recommended.
I eat one bowl of Cream Of Wheat every day which has nine milligrams and have stopped taking the multi-vitamin with iron. Everything is back to normal for me in that regard.
Best of luck and just thought I would share my experience.