Few people realize that it IS possible to overdose on certain vitamins. Here's a few you might want to watch out for:
Vitamin B6: More than 100mg a day might cause nerve damage
Vitamin C: One study indicated that consuming high doses of Vitamin C increases the risk of developing kidney stones among men
Vitamin D: Taking over 10,000 IUs a day may lead to problems like loss of appetite and kidney problems
As always, consult your medical professional about any vitamins you may be taking.