Many health problems come with a tagalong: sexual dysfunction. Are the home fires burning less brightly lately? It might be time for a checkup. Here are a few medical conditions and situations whose impact can be felt in the bedroom:

Vascular disease. Several vascular conditions can express themselves as sexual problems. With time, they harm blood vessel, hardening and tapering arteries, which can restrict blood flow to the genitals. For men, this may translate into inefficient erections; for women, inadequate lubrication. Studies indicate that blood vessel disease could be behind 50 percent to 70 percent of men's erectile dysfunction, according to the Cleveland Clinic.

Diabetes. Sex problems often coexist with diabetes and its attendant complications—especially vascular disease and nerve damage. Men may experience erectile or ejaculatory dysfunction, while women may face decreased arousal and difficulty achieving orgasm. The risks of these sexual side effects may be reduced by keeping blood sugar, blood pressure, and cholesterol in check, according to the National Institute of Diabetes and Digestive and Kidney Diseases.

Depression. Sexual dysfunction often accompanies depression, since the brain, commonly called the "the largest sex organ," is where that spark of sexual desire originates. If brain chemicals, or neurotransmitters, aren't properly balanced, libido, arousal, and orgasm can take a hit. Frustratingly, antidepressants such as selective and nonselective serotonin reuptake inhibitors that act on serotonin receptors may dampen desire, decrease arousal, and stall or squash orgasm. Luckily, antidotes exist. Studies (supported by Pfizer) have found that Viagra and Viagra-like medications may help, and some physicians have had success with the antianxiety medication buspirone. Switching antidepressants might work, too.

Menopause. Women's sex lives may change as certain hormones begin to wane. A drop in estrogen, which aids in arousal, often results in vaginal dryness and painful intercourse. Testosterone—a hormone tied to libido in both sexes—is on the decline as ovaries, which produce roughly half a woman's testosterone, shut down. While testosterone deficiencies won't always create problems, low levels of the hormone may kill a sexual appetite.

Medication side effects. Countless medications can affect what goes on between the sheets. Besides antidepressants that act on the brain's serotonin receptors, certain high blood pressure medications, and even the birth control pill, can sap libido and have other sexual side effects. Subbing a different drug or a lower dosage may make a difference.

Multiple sclerosis. Multiple sclerosis, a disease of the central nervous system, is known to impair sexual function. Unsatisfactory erections and poor arousal and orgasmic dysfunction in women may sometimes be indicators of this potentially crippling lifelong condition. Other neurological disorders such as Parkinson's can create similar trouble.

Endometriosis. More than 5 million women in North America have endometriosis, a condition in which tissue that should normally line the uterus grows elsewhere, according to the National Institutes of Health. Along with symptoms like painful cramps, heavy periods, and chronic pelvic pain, sex for these women can be an excruciating ordeal.

Ovarian cysts. Painful sex may also be a sign of an ovarian cyst, a fluid-filled sac on the ovary; pelvic inflammatory disease; or even pelvic cancer. Sexual pain, experts say, shouldn't be ignored.

Thyroid dysfunction. The thyroid, a butterfly-shaped gland perched at the front of the neck, has important responsibilities. It governs the body's metabolic processes, from temperature to weight, and can also play a key role in sexual health A faulty thyroid producing either an over- or underabundance of hormone may be associated with erectile and ejaculatory problems, a change in libido, or a difficulty with lubrication and orgasm in women. Thyroid conditions are treatable, says Irwin Goldstein, director of sexual medicine at San Diego's Alvarado Hospital.