Hi ThereIron is well known for causing C but I am not sure how it would affect you! Don't know if any of the following will be of any use to you....If you are feeling really that lethargic, and can't work out why it is worth seeing your doctor, there may be something else they can suggest (your iron levels may be ok)...I saw my dietitian about iron because I was trying to find out what and what not to eat (being a vegetarian and not eating the red meat!) She advised that a lot of your iron can be taken from you food (even wholemeal bread being a good source) and have found out the following:Iron rich foods should not be eaten with fizzy drinks as they (the drinks) contain something which slows the absorbtion of iron.Vitamin C (ie drinking orange juice) taken with iron rich foods however help the absorbtion of the iron.The B Vitamins are also good if you are feeling lethargic (don't know what sex you are but they are especially good for women) I believe you can get various iron rich tonic things in health food shops. The staff would probably know a bit more about any side effects though...