Long-term treatment with bisphosphonates may increase bone fragility by suppressing normal bone remodelling -a process essential for repair of skeletal microdamage. Atypical femoral fractures have been reported (rarely) with bisphosphonate therapy, mainly in patients receiving long-term treatment for osteoporosis.
The need for continued treatment should be re-evaluated periodically based on the benefits and potential risks of bisphosphonate therapy for individual patients, particularly after 5 or more years of use. Because the effects of bisphosphonates lasts for several years after the bisphosphonate has been stopped it is reasonable to consider a treatment break (‘drug holiday’), see here for PIL.
A useful resource is included below: