If the controversy about some bone-building drugs has you confused about whether you should be taking them, you are not alone. The drugs in question, called bisphosphonates, brand names Fosamax, Actonel, Boniva, Reclast and Atelvia, are widely used in the United States to treat osteoporosis, which can lead to fractures. The controversy stems from reports that a very small number of users suffered unusual thigh fractures or a serious jaw disease.

In 2011, two U.S. Food and Drug Administration (FDA) advisory panels recommended changes to the drugs’ labeling – but they could not come to a definite conclusion on how to change it. “There is no easy, one-size-fits-all answer,” says bone specialist Elizabeth J. Shane, MD, a professor of medicine at Columbia University in New York City. “As with any medication, you have to weigh the risks and the benefits.”

The Benefits

Bisphosponates work by slowing bone loss, which results in increased bone density. After about three years, bone density plateaus, staying at a stable level as long as the medication is taken. This increased bone density translates into fewer osteoporotic fractures.

“We have quite a bit of clinical experience with these drugs now, and we know they are quite effective in reducing fractures,” says Kenneth Saag, MD, a professor in the division of clinical immunology and rheumatology at the University of Alabama at Birmingham.

The Risks

Besides the common side effects of stomach upset and heartburn, rare but serious side effects have been reported, largely by people who have taken bisphosphonates for more than five years. One is an atypical fracture of the femur, or thighbone. These atypical fractures aren’t the result of a fall; they happen suddenly, while walking or even standing still.

Some patients reported an even rarer side effect – osteonecrosis of the jaw, or death of part of the jawbone. Most people with this condition were taking bisphosphonates as part of cancer treatment, at 10 times the dose prescribed for osteoporosis.

Who Should Take Them?

It is not yet known if bisphosphonates have benefits or safety concerns after five years. However, for people who have osteoporosis and are at a high risk of fractures, bisphosphonates offer significant protection and carry little risk during the first three to five years.

These drugs also offer significant benefits for people with autoimmune forms of arthritis, such as rheumatoid arthritis, who take high-dose corticosteroids, which can weaken bones. “In [those] who have a very high risk of fracture, the benefits outweigh the risks,” says Clifford J. Rosen, MD, a professor at Tufts University School of Medicine in Boston and member of the FDA Drug Safety and Risk Management Advisory Committee, one of the two panels that looked into the labeling issue. Otherwise healthy people with osteopenia – low bone density that isn’t severe enough to qualify as osteoporosis – may not want to take bisphosphonates to prevent bone fracture.

“These drugs have not been shown to reduce fracture risk in the osteopenia group,” says Dr. Rosen. In the absence of conclusive, scientific evidence, the decision to continue using bisphosphonates more than five years must be between a patient and physician. “But if treatment is indicated, you shouldn’t be so afraid of these very rare side effects that you don’t treat a very common problem,” says Dr. Shane.