I was prescribed iron tablets a few months ago. I was just below the threshold and took 2 a day. However, I have suffered from an upset stomach - wont go into details, but I was visiting the toilet regularly, so I stopped taking them and contacted the surgery asking if I could have a blood test to see if I still needed them. Luckily they agreed so I'm not taking them at the moment. If I hadnt asked that I would probably be taking them foreverMost vitamins you just pee out. The important ones D, C and be careful of iron unless the doctor says you need it.
Iron can wreck your liver and even kill you if you take too much.