Never stop taking vitamins.
Not sure why you would need any break from a multivitamin unless you have a health condition that prohibits taking certain nutrients in one, such as someone who has been told not to take any supplemental iron for example (there are many iron-free multis, this is just an example). You don't say which one you're taking, and that can make a difference as well. If it's a typical one a day, which have become more popular lately, frankly, there's so little in any of them that there's really no reason to ever stop unless you just want to stop because you don't think they are necessary or useful. If it's a mega-vitamin which means it has a lot more than recommended daily amounts and would have to be a several pills a day vitamin to do that, I can see why one might not want to take it at all. If it's a multiple pill one that simply has a lot of food in it and not mega doses of isolated nutrients, and these aren't as prevalent as they used to be as many of the best companies seem to be moving to one a days or two a days and again, you just can't fit that much into one or two pills to do much harm. The purpose of a multi is just to provide a cushion in case you just aren't getting enough of something in your food so you at least have some rather than none of a particular nutrient. It's purely prophylactic. If one were to eat perfectly well, there would be no need for a multi but it's pretty much impossible to do that. If you're buying a drug store brand rather than a really good one you can only find in health food stores, much of what's in it isn't well absorbed anyway so again, you're not really getting all that much. Now, if you're taking single nutrients for particular purposes, you have a better chance of getting too much of something, but even here, if you're taking it for a particular purpose that purpose probably doesn't come and go. Say, vegans who need to supplement with B12, or those who don't get any sun needing D. So again, don't see the reason for cycling, but if it feels better to you to do that, there's no big harm in it, you're just giving up whatever benefit you believe taking a multi gives you for that period of time. Again, have no idea what you're taking or if you're using the term multi to refer to lots of separate vitamins, I'm assuming you really mean a multi-vitamin, which by definition has a little of a lot of different nutrients in it.