Every time I've started taking Multivitamins I start getting muscle spasms much more often. I've tried different kinds and always the same thing, after about a week I start getting muscle spasms all the time. At first I didn't think it could be the MV, but I have stopped and started so many different times and the same thing always happens, stop taking them and the spasms get better and go away, start and they start getting more and more frequent. Pharmacist said it can be a side effect but happens in less than .5% of people. Lucky me.