Q - Can birth control pills diminish my sex drive?

A - Some birth control pills can decrease the intensity of sexual drive and sensations and some can increase it. The effects depend in part on the chemistry of your body and the formulation of the hormones in the pill you take.

The formulations that cause fewer of the common side effects associated with birth control pills -- headaches, weight gain, nervousness, acne, malaise and irritability -- are also the pills that may decrease sexual responsiveness. So, selecting the best pill for an individual woman can become a very delicate balancing act, often requiring that women try a pill, then wait and see what its effects are.

According to Dr. Arnold Kresch, a gynecologist at Helena Women's Health in Palo Alto, Calif., the greater the level of androgenic potency in the pill, the greater the potential for side effects. Yet, androgens, the male sex hormones, are in large part responsible for physiological sexual response in women. So, pills with low androgen potency can decrease the intensity of a woman's orgasm while at the same time possibly causing fewer side effects.

As new pills are developed, new classes of progestins, female sex hormones, are being used in them. When free testosterone levels are measured in the bloodstream of women taking these new progestin birth control pills, the levels are often found to be lowered. And that's a problem that has not been ironed out yet.