It is quite dangerous to your health and wallet to use multivitamins for general purpose. If you do not have a specific deficiency or condition that a doctor has recommend taking a vitamin for, you will get no health benefit.
Tons of recent studies have shown general use for preventative reasons range from no effect to an increased mortality rate. So taking vitamins just because you think it will make you healthier can and does have the opposite effect. Taking a vitamin for medical reasons is different. If you don't believe me, just type vitamin study into the search engine of your choice.