I use a chinese herb my naturopath suggested to me. I think you can only get it through a naturopath or similar.
Its Dang Gui & Gerdenia, and i got it given to me because of my skin, but it also aids in the relief of pre-menstrual and menstrual signs and symptoms, and its really good!!! It also has other benefits such as giving you more energy etc.
It tastes absolutely ferral, but well worth it!!!