Bisphosphonates (such as alendronate, risedronate, and zoledronic acid) are a common class of medications that slow the breakdown of bone, helping to preserve bone density and reduce fracture risk. They are often first-line for osteoporosis.
They are generally well tolerated and effective. Rare side effects — such as osteonecrosis of the jaw and atypical thigh-bone fractures — are worth knowing about but are uncommon, and for people at real fracture risk the benefit usually outweighs them. See osteoporosis treatment; this is a clinician decision.