Why is it that on every birth control pill ive tried so far ( at least 6 different kinds ) i keep having vaginal dryness and low libido?

Birth control pills : Today's oral contraceptives are very low dosage, so taking them punctually (within the same hour as the previous day's active pill) is necessary to maintain a constant level of the hormones in the bcp's. Short low to absent hormone levels mimic the symptoms of the week on the "sugar" pills, and vaginal dryness with low libido can result.