Hello, is it allowed to use tantum rosa (vaginal douche) during the menstruation?

Best to use none: during menses. In fact, it's probably not necessary to use at all. Usually there's no need for douching. If you feel you need to do this on a continuous basis, you should talk to your PCP, or GYN doctor. Often, the pH isn't that good, and if you are trying to eliminate smells, there may be something else cooking. Consult your doctor first.