Some women notice diminished interest in sex while taking BCPs, sometimes mild, and sometimes profound.

There can be many other possible causes of decreased libido, including stress and relationship problems. But in this clinical setting, two hormonal causes for decreased libido stand out: decreased testosterone and ovulation suppression.

Both men and women produce the male hormone, testosterone. Men produce quite a bit of it, and women, only small amounts. But the small amount of testosterone produced by women is very important to their sex drive, and feelings of well-being.

Whenever ovarian function is suppressed by BCPs, a woman’s testosterone level usually drops by about one-third. While this drop is not typically noticed, some women who are particularly sensitive to testosterone may notice lessening of their sex drive. (“Doc, since starting the pill, I’ve had zero interest in sex. Why is that?)

While each woman’s sexual interest may vary, studies have found that many women have an increased sex drive for several days around mid-cycle, coinciding with ovulation and the estrogen surge that accompanies ovulation. This should not bee too suprising as it facilitates human reproduction and survival of the species. But women whose ovarian function is suppressed do not ovulate and do not have the mid-cycle surge of estrogen that is associated with sexual interest.

There are a number of approaches to this problem that may prove effective in resolving it:

• While it is theoretically possible to overcome this problem with additional testosterone, most physicians would recommend stopping the BCPs to allow the testosterone levels to return to normal and ovulation to resume. These women will then use alternative methods of birth control.
• Changing the BCP to less strong progestin pill, with a shorter half life can be tried. These less strong pills still provide contraception, but are less consistent in their suppresion of ovarian function. If ovarian function is not suppressed, then ovulation will continue and testosterone will not be depressed.
• If there is any chance that other, non-hormonal causes for decreased libido, such as relationship problems, then professional counseling and/or behavioral modification may be useful.