Some hormonal birth control methods such as pills and patches can increase women's levels of sex-hormone-binding globulin (SHBG), which drops the amount of testosterone that's floating around freely in the bloodstream.
A small but alarming 2006 Boston University study, authored by Irwin Goldstein, MD, director of San Diego Sexual Medicine and editor in chief of The Journal of Sexual Medicine, found the Pill to have a long-term effect on libido in some women. The level of SHBG was twice as high in women who had taken the Pillfour months after they'd stopped taking the medicationas those who never had.
That kind of long-term effect is pretty rare, however, according to Hilda Hutcherson, MD, an ob-gyn professor at Columbia University. She finds that birth-control-related sex drive problems usually go away when her patients switch pill formulations. "It's the progestin that seems to affect libido," Dr. Hutcherson says. "Some progestins have an androgen [male hormone] effect, and those tend to have less effect on libido."
Selective serotonin-reuptake inhibitors (SSRIs) such as Prozac are supposed to cheer you up, but they can interfere with one potential source of happiness: sexual pleasure. Some doctors will keep the SSRI but add Wellbutrin, which increases dopamine and acts as an "antidote to the SSRIs," according to Dr. Goldstein. For others, a doctor might switch the patient to Wellbutrin and cut the SSRI.
Everyone's body reacts differently to drugs, however, and for some, depression itself is more of a sex drive dampener than the SSRIs are. For still another set of patients, notes Marjorie Green, MD, director of the Mount Auburn Female Sexual Medicine Center in Cambridge, Mass., and a clinical instructor at Harvard Medical School, "When you give them SSRIs, they get a libido and can be sexually functional when they weren't able to be before."