negative effects of vitamin supplements?

Too much of fat soluble vitamins are harmful for the body as they cannot be excreted fast.For eg.too much of Vit.A can cause a condition called Benign Intra cranial Hypertension

There are tons of repercussions to improper use of any chemotherapeutic drug. Docscholl's got the idea with the consult your physician bit. There are few you can't OD on and some of them can have life-threatening consequences. Also, unless someone is clearly aware of your usage, it makes some of the resulting illnesses hard to identify right out of the blocks. There are some that are readily apparent, but there are those that can be proven fatal, especially if it isn't one that is a commonly taken supplement. Also to the comment about multivitamins. You CAN OD on those as well. The question is, what do you do, whats the mg on your dosage, are you active? anything else you take? medical conditions? there's a bit too much to ask that a personal physician would be more properly equipped to answer. Likelyhood? Many people need more vitamin B (all of them) and SOME D and C, particularly if you are fair skinned or don't get a ton of sun. Do you most likely need all of those? Not likely. Will it most likely be detrimental? Not likely, but it is still worth a visit, especially looking long term if you did need it or shouldn't have taken in, considering how long you may need or want to take it.