Rebound fracture risk (denosumab)

Denosumab (Prolia) works by blocking RANKL, a signal that activates bone-eating cells called osteoclasts. As long as the drug is in your system, bone breakdown stays suppressed. But unlike bisphosphonates, denosumab doesn't stay stored in bone — so when a dose is delayed or stopped, its effect wears off fairly quickly, and osteoclast activity can swing back up, sometimes higher than before treatment started.

This 'rebound' effect means bone can be lost rapidly in the months after discontinuation, and there have been reports of multiple vertebral compression fractures occurring in this window, even in people without prior spine fractures. This is different from most other osteoporosis medications, where stopping simply means you gradually return toward your pre-treatment risk level.

Because of this, denosumab is generally not a drug to pause or stop without a plan. Doctors often recommend transitioning to another medication, such as a bisphosphonate, to help hold onto the bone density gained and blunt the rebound effect. If you're on denosumab and considering a change for any reason, this is a conversation to have with your prescriber rather than a decision to make alone.