However, what works even better than Viagra for many men with erectile dysfunction, McKinlay says, is increasing one's physical activity, kicking the smoking habit, and watching one's weight and cholesterol. As erectile dysfunction is related to cardiovascular disease, such changes can also reduce the risk of the biggest killer of men in the world.

If that doesn't do it, then McKinlay suggests men work with their doctors to change medications before trying medication specifically for erectile dysfunction. As a last resort, a number of invasive treatments are available.

Meanwhile, older women experience reduced vaginal lubrication and reduced blood flow to sex organs, and the intensity of muscle spasms during an orgasm are diminished. These and other issues can be addressed through estrogen replacement therapy and something as simple as using lubricants.

Although some recommend and swear by such alternative therapies as ginkgo biloba or an amino acid called L-arginine for libido and erection problems, McKinlay says there's no scientific data that shows hormone supplements, herbs or dietary supplements work to address erectile dysfunction. However, that's not to say alternative medicine won't work, he adds.

Strategies for Keeping the Spark Alive

• Treat your partner as if you're dating
• Romance your spouse outside the bedroom
• Plan a date night
• Talk with your partner
• Listen to your partner
• Understand your partner's sexual needs and desires
• Keep physically fit and attractive for your partner
• Maintain perspective on sex as life ebbs and flows
• Resolve any underlying conflicts as they will spillover to the bedroom
• Have fun and engage in foreplay, whether that's kissing, sexual banter or anything else
• Be adventurous and creative in and outside the bedroom
• Exercise, preferably together
• Stop smoking and get your partner to quit
• Watch your weight and cholesterol
• Consider seeking specialized treatment from a specialist if behavioral changes don't work