Osteoporosis is often considered to be a female condition, but it occurs in men and women. In the United States, approximately 10 million individuals – including 20% of women past menopause and 16% of elderly men – currently have osteoporosis. Among women 80 years of age an older, the prevalence of osteoporosis is 70%. As the U.S. “baby boomer” population ages, the percentage of adults with osteoporosis is expected to increase. Men in the United States typically get the condition 10 years later than women and experience higher rates of mortality following their first osteoporosis hip fracture. Worldwide, 200 million women are currently estimated to have osteoporosis.

Primary osteoporosis occurs most often in post-menopausal women, while secondary osteoporosis occurs most often in men and pre-menopausal women. Type I primary osteoporosis typically occurs in people between 50 and 70 years old, and type II occurs primarily after age 70. The diagnosis of osteoporosis in children and adolescents is controversial because too little is known about whether the standard adult diagnostic criteria have clinical value for younger age groups. Currently, for a child or adolescent to receive a diagnosis of osteoporosis, the minor would typically need to have a combination of low bone density and one or more fractures that can be attributed to bone fragility.

Because osteoporosis is chronic and gets worse over time, the medical profession has adopted the view that patients should be treated for the rest of their lives. There isn't much data on what happens when you stop taking bisphosphonates and all osteoporosis drugs because nobody wants to do that experiment. However, alendronate stays in the body for years. Indeed, the "terminal half-life" is 10.5 years, which suggests that the drug may continue to work for years after the patient stopes taking it.