"With the launch of the first prescription osteoporosis medication  years ago millions of Americans with the bonethinning disease began taking the drugs and never looked back. But now many bonehealth doctors are looking back and becoming increasingly uneasy. In the last few years evidence has emerged that longterm use of osteoporosis drugs  particularly the oldest class of drugs the bisphosphonates  may do more harm than good. Some doctors are starting to tell at least some of their patients to stop taking the drugs for a time  in other words to take a drug holiday. That strategy is a tough sell for consumers who have been bombarded with osteoporosis medication advertisements for years. When osteoporosis drugs first came out people thought this is a recurring disease like high blood pressure. So why wouldnt you treat it for the rest of their lives said Dr. Richard Eastell an expert in bone metabolism at the University of Sheffield in Britain who spoke about the issue last month at the annual meeting of the American Society for Bone and Mineral Research. But there are now some anxieties with longterm use. Several factors are merging to usher in a new era of caution surrounding the medications. One is the simple acknowledgment that some people are approaching  to  years of continuous use.   Worldwide its a commonly discussed question as to how long you should go on with these treatments Eastell said. Beyond  years we have no knowledge of how these treatments work. Added to that several potential risks from longterm use have recently arisen. In rare cases people taking bisphosphonates  which include Fosamax Boniva Actonel and Reclast  can develop jaw necrosis a condition in which the jawbone begins to deteriorate. And a study published in September in the British Medical Journal found that people who take bisphosphonate drugs for several years have a slightly higher risk of developing esophageal cancer. Experts dont know why the drugs would increase the cancer risk although they are known to irritate the esophagus in some people. Of most concern however is that longterm bisphosphonate users can develop rare and unusual fractures in the thigh bone or femur. A  study first linked longterm use of the medications to femur fractures and other research has confirmed the link. On Oct.  the Food and Drug Administration announced it will now require bisphosphonate drugs to carry information on their labels describing the risk of rare femur fractures. Without a lot of clear scientific evidence to guide them doctors are debating how long people should take bisphosphonates and whether occasional drug holidays are a good idea. Bones grow and change. After reaching peak bone mass in the early or mids bone density begins to decline because old bone is lost faster than new bone is made. This process speeds up in midlife especially after menopause in women. Bisphosphonates work by preventing the body from reabsorbing bone. They slow bone loss but also interfere with the natural boneremodeling cycle the process by which old bone is continually broken down and new bone is fashioned to replace it. This interference its thought lies behind the unusual fracture risk. And some bone specialists believe that leaving bones free of drugs for a year or more in people with osteoporosis allows the boneremodeling process to kick in again. Drug holidays may also be justified these specialists say because bisphosphonate medications remain in bone tissue for a year or two after people stop taking them. A study in  followed postmenopausal women who took Fosamax for five years at which point half of the women stopped taking the drugs and half continued. At the end of the year period there was no difference in fracture rates among the two groups. To give high doses indefinitely is not what you want to do said Dr. Ian Reid an endocrinologist and bone expert at the University of Auckland in New Zealand. After five years its a good time to reassess. If the bones dont show osteoporosis we typically stop the drug and monitor bone density. If they still have osteoporosis readings or have had a fracture we keep them on medications for out to  years.   People who still have osteoporosis also have the option of switching to a different class of drug. One is the parathyroid hormone drug teriparatide sold under the brand name Forteo which unlike the bisphosphonates works by actively building bone. Another is the new medication denosumab brand name Prolia which is in a drug class known as the RANK ligand inhibitors. As the name suggests it suppresses bone breakdown by inactivating a protein called the RANK ligand. Its too early to tell if longterm Prolia use causes some of the same side effects as bisphosphonates."