Maybe you're not feeling amorous because you're annoyed with your partner for not taking out the trash, or you're taking medication that dulls your sex drive. But some doctors say that in about a third of their patients, a drop in libido is medical—a result of heart disease, a thyroid or other hormone imbalance, diabetes, or hypertension.

Any major sexual change should be taken seriously and checked out by a doctor to find out whether the root of the problem is physical or psychological. "There should be no difference between someone who has low libido and someone who has arthritis," says Irwin Goldstein, MD, director of San Diego Sexual Medicine and the editor in chief of The Journal of Sexual Medicine. "It's a health condition and it needs to be evaluated by a physician."

The good news—if the cause is medical—is that it opens up a whole range of treatments. Your doctor may prescribe a combination of lifestyle changes and medication focusing first on the underlying disease or condition itself.

Very commonly that means heart disease or diabetes. But Michael Krychman, MD, executive director of the Southern California Center for Sexual Health and Survivorship Medicine in Newport Beach, Calif., finds that 10% to 15% of women who come in for low libido have untreated thyroid problems that can be handled quite effectively with medication.

There should be no difference between treating someone who has low libido and someone who has arthritisclose quote
—Irwin Goldstein, MD, Sexual Medicine Specialist
Low testosterone or estrogen is also commonly linked to sex drive problems; postmenopausal women may be prescribed topical estrogen (or sometimes oral estrogen); older men with low levels may be treated with testosterone patches or shots.