My experience with BC is the opposite of most.... I have a very, very strong, active libido. I was diagnosed with PCOS several years ago, and the doctor told me that I have fairly high levels of testosterone, and really low levels of estrogen.
I started taking BC to help even the levels of estrogen, and when I did, it was like someone let the crazed nympho out of the cage.... I'd not really noticed a decrease in my sex drive, but evidently my husband had noticed. As my testosterone levels rose, my sex drive decreased.... Not to the point where I didn't ever want sex... My hubby teases me that PCOS gave me a "normal" libido, lol... But to the point that when BC put my hormones back to a more normal level, I regained my natural, normal-for-me active libido.
I don't take BC anymore (I don't like the side effects), so my libido has gone back to "normal" normal, lol. At least now I'm not driving my hubby crazy, chasing him around trying to molest him. *grins*