Unless you are pregnant, there is absolutely no way you can naturally block your menstrual cycle. There is no provision in nature which can prevent you from experiencing your monthly period. But a more pertinent question would be why you would want to block your menstrual cycle in the first place. This is a highly unnatural thing and you are advised not to tamper with your body in such ways, which can ultimately cause more harm than good. Keep in mind that the menstrual cycle does not really come and go like clockwork for most women. It is almost always off by a day or two or sometimes even a week or so.. In any case, sometimes, the onset of some new physical activity which is undertaken very suddenly and strenuously can have the effect of stopping your menstrual cycle. For example, if you are not really used to exercise and you suddenly start working out a whole lot and with some element of regularity, you can almost always be sure that your menstrual cycle will be adversely affected. Of course the amount and type of exercise you do would also make a difference. For example, if you indulge in something like cycling or swimming, you will discover that this can either stop your periods from appearing, or sometimes even make them appear far earlier or far later than expected.
However, there is absolutely no guarantee of any sort that this method can provide. If it is so completely essential for you to stop your period or even to delay it, then you should consult your gynecologist. Your gynecologist will be able to recommend various methods and you can discuss the pros and cons of each to find one that is most suited to your needs. It would be better not use over the counter medication because any kind of drug taken without medical supervision can sometimes backfire badly. This is especially true, if you are currently on other medications as there could be an adverse interaction between the two medications. In addition to this, several pills have serious side effects that need to be countered. Some medications interfere with calcium and absorption and so you may have to take mineral supplements. Your own gynecologist will also know your medical history which always makes a very big difference when undergoing treatment of any kind, no matter how short or temporary it may be. Once again, the best advice you can get is to not interfere with your cycle, especially not without medical advice and supervision.
answered by G M