how weird i was going to ask this exact same question! Vitex has a few names, one of them being Monk's Berry because Monks would take it to decrease libido. From what i have read it's supposed to be very effective in regulating irregular cycles and is even approved by the German Commission E (the German governmental agency that evaluates the safety and effectiveness of herbal products). But I have not read anything that says it will decrease a woman's libido.
I know I've seen some posters mention it... Has anyone that's taking it experienced a decrease in libido??? Just like pinkkangaroo said, that's definitely not what I want either.