Several classes of prescription medication can slow bone loss, rebuild bone, or both, and the right choice depends on how severe the osteoporosis is, what’s driving it, and how high the fracture risk has become. The most widely prescribed drugs are bisphosphonates, but newer options like denosumab and romosozumab have changed how clinicians think about treatment sequencing. Understanding what each medication does and how it fits into a broader plan matters, because the order in which these drugs are used can make a real difference in outcomes.
Why Bones Weaken in Osteoporosis
Bone is living tissue that constantly rebuilds itself. Specialized cells called osteoclasts break down old bone, and osteoblasts lay down new bone to replace it. In healthy adults, these two processes stay roughly in balance. Osteoporosis develops when that balance tips toward more breakdown than building, and the skeleton gradually becomes porous and fragile.
Sex hormones play a central role in keeping this system calibrated. The loss of estrogen after menopause or the decline of testosterone in men can accelerate bone breakdown and raise fracture risk substantially.1PubMed. Bone remodeling in post-menopausal osteoporosis Postmenopausal osteoporosis, the most common form, is fundamentally a problem of osteoclasts outpacing osteoblasts.2PubMed Central. Neddylation of NFATc1 and Runx2 regulates osteoclast-osteoblast balance and represents a dual-action therapeutic target for postmenopausal osteoporosis Nearly every medication for osteoporosis works by intervening in this imbalance, either by slowing the osteoclasts, speeding up the osteoblasts, or doing a bit of both.
Bisphosphonates
Bisphosphonates remain the first-line treatment for most people with osteoporosis. The class includes oral medications like alendronate (Fosamax) and risedronate (Actonel), as well as intravenous options like zoledronic acid (Reclast) and ibandronate (Boniva). They work by latching onto bone surfaces and disrupting the machinery inside osteoclasts. When an osteoclast lands on a bisphosphonate-treated bone surface to start resorbing it, the drug shuts down a key enzyme the cell needs to function, causing the osteoclast to detach and stop breaking bone down.3Journal of Clinical Investigation. Bisphosphonates for osteoporosis: from bench to clinic – Section: Biological targets of bisphosphonates The newer nitrogen-containing bisphosphonates are considerably more potent because they also trigger toxic byproducts inside the osteoclast that compromise its survival.4PubMed. Biochemical and molecular mechanisms of action of bisphosphonates
In clinical practice, these drugs deliver meaningful fracture reduction. In randomized trials, alendronate, risedronate, and zoledronic acid have all been shown to reduce vertebral, non-vertebral, and hip fractures, while ibandronate’s evidence is strongest for vertebral fractures specifically.5PubMed Central. Long-term treatment with bisphosphonates and their safety in postmenopausal osteoporosis One study of postmenopausal women found that new fractures dropped from about 37% before bisphosphonate therapy to roughly 15% after treatment.6PubMed Central. Efficacy of Bisphosphonates in Reducing Fracture Risk Among Postmenopausal Women With Osteoporosis
The oral versions need to be taken on an empty stomach with a full glass of water, and you have to stay upright for at least 30 minutes afterward to avoid irritating the esophagus. That fussy routine contributes to poor adherence, which is one reason some doctors prefer the intravenous options, particularly once-yearly zoledronic acid.
Bisphosphonate Safety and Drug Holidays
Two rare but serious complications have attracted attention with long-term bisphosphonate use. Osteonecrosis of the jaw is a condition where a patch of jawbone loses its blood supply and begins to die, often after dental procedures. Among osteoporosis patients on standard doses, this is rare, with estimates ranging from roughly 1 in 10,000 to 1 in 250,000.7ScienceDirect. Osteonecrosis of the Jaw and Atypical Femoral Fractures – Section: Abstract The risk is far higher in cancer patients who receive much larger intravenous doses. Risk factors include dental extractions, periodontal disease, and longer duration of use.
Atypical femoral fractures are unusual breaks in the thigh bone shaft that can occur with prolonged therapy. They appear to be related to the same mechanism that makes bisphosphonates effective: by suppressing bone turnover so thoroughly over many years, the bone may lose some of its ability to repair microscopic stress damage. The absolute risk remains low, but it climbs with duration of use, particularly beyond five years.8PubMed. Pathophysiology of atypical femoral fractures and osteonecrosis of the jaw
Because bisphosphonates accumulate in bone and keep working for a while after you stop taking them, clinicians often recommend a “drug holiday” after an extended course. Current evidence supports offering a holiday of three to five years for patients who have been on oral bisphosphonates for five years (or intravenous for three years), provided their hip bone density isn’t severely low and they haven’t had recent vertebral or hip fractures.9PubMed Central. Bisphosphonate Drug Holidays in Primary Care: When and What to Do Next? The risk of atypical fractures drops quickly once bisphosphonates are stopped. However, the decision is individualized. One study found that patients who discontinued risedronate for one to two years before experiencing a hip fracture had higher post-fracture mortality, though this was not seen with alendronate.10The Journal of Clinical Endocrinology & Metabolism. Effect of Oral Bisphosphonate Drug Holiday on Mortality Following Hip Fracture – Section: Results That kind of finding underscores why drug holidays need careful monitoring rather than a blanket policy.
Denosumab
Denosumab (Prolia) takes a different approach to slowing bone breakdown. Rather than poisoning osteoclasts directly, it blocks a signaling molecule called RANKL that osteoclasts need to mature and survive. Given as a subcutaneous injection every six months, denosumab reduces bone turnover, increases bone density, and lowers fracture risk.11PubMed Central. Denosumab for the treatment of osteoporosis Many patients find the twice-yearly injection easier to stick with than daily or weekly oral pills.12PubMed. Patients’ first-year adherence to different anti-osteoporotic therapy after hip fractures
The biggest concern with denosumab isn’t a side effect while you’re on it; it’s what happens when you stop. Unlike bisphosphonates, denosumab doesn’t stick around in bone after discontinuation. Once the drug clears the body, osteoclast activity rebounds sharply, often surging beyond pre-treatment levels. Bone density can plummet rapidly, and some patients develop multiple vertebral fractures during this rebound window.13PubMed Central. Denosumab Discontinuation and the Rebound Phenomenon: A Narrative Review A systematic review by the European Calcified Tissue Society confirmed that clinical trials and case series both show steep bone turnover increases and rapid bone loss after stopping denosumab, with a concerning signal for multiple vertebral fractures.14PubMed. Discontinuation of Denosumab therapy for osteoporosis: A systematic review and position statement by ECTS For this reason, anyone coming off denosumab should transition to another therapy, typically a bisphosphonate, to blunt that rebound. You cannot simply stop denosumab the way you might pause a bisphosphonate.
Bone-Building Medications
All of the drugs discussed so far are anti-resorptive: they work by slowing bone breakdown. Anabolic medications flip the equation and actively stimulate new bone formation. Two are currently available: teriparatide (Forteo) and abaloparatide (Tymlos). Both are synthetic versions of parathyroid hormone-related molecules, delivered as daily subcutaneous injections.
This seems counterintuitive because parathyroid hormone, in excess, actually causes bone loss. But when given in small intermittent pulses (a brief daily injection rather than continuous exposure), these drugs preferentially boost osteoblast activity, so that formation outpaces resorption.15PubMed Central. Anabolic therapy for osteoporosis: update on efficacy and safety Abaloparatide was designed to cause less stimulation of bone resorption than teriparatide, keeping the “anabolic window” open longer.16PubMed. Abaloparatide, the second generation osteoanabolic drug: Molecular mechanisms underlying its advantages over the first-in-class teriparatide
Both drugs are limited to about two years of use, after which the bone-building effect tapers. And critically, the gains don’t last on their own. Once you stop an anabolic agent, the new bone can be lost if it isn’t preserved with an anti-resorptive drug afterward. That’s why these medications are almost always followed by a bisphosphonate or denosumab.
Romosozumab
Romosozumab (Evenity) is the newest addition to the osteoporosis toolkit and is the only drug that simultaneously increases bone formation and decreases bone resorption. It works by blocking a protein called sclerostin, which normally acts as a brake on bone building.17PubMed Central. Profile of romosozumab and its potential in the management of osteoporosis In a large trial of postmenopausal women, romosozumab reduced new vertebral fractures by 73% compared to placebo at 12 months.18PubMed. Romosozumab Treatment in Postmenopausal Women with Osteoporosis
Romosozumab is given as a monthly injection for 12 months, then followed by an anti-resorptive drug. It carries a boxed warning about cardiovascular risk based on a trial that compared it to alendronate, in which more cardiovascular events were observed in the romosozumab group. However, more recent observational data comparing romosozumab to denosumab in real-world patients found no significant difference in the risk of major cardiovascular events at either one or three years of follow-up.19Endocrinology and Metabolism. Risk of Cardiovascular Events in Patients with Osteoporosis on Romosozumab Treatment Compared with Denosumab: A Multicenter Observational Cohort Study Most clinicians avoid prescribing it to patients who have had a recent heart attack or stroke, but the cardiovascular concern may be less clear-cut than the warning label suggests.
Raloxifene and Selective Estrogen Receptor Modulators
Raloxifene (Evista) belongs to a class of drugs that mimic estrogen’s protective effects on bone without acting like estrogen everywhere in the body. It increases spinal bone density by a modest amount and reduces vertebral fractures by roughly 30% to 50% in postmenopausal women with osteoporosis. However, it has not been shown to reduce hip fractures or other non-vertebral fractures, which limits its usefulness for people at highest risk of those breaks.20PubMed Central. Raloxifene for older women: a review of the literature
Where raloxifene gets interesting is its off-skeleton effects. It lowers LDL cholesterol and reduced the incidence of invasive breast cancer by about 72% in postmenopausal women with osteoporosis during a large prevention trial.21PubMed. Benefit-risk assessment of raloxifene in postmenopausal osteoporosis The trade-offs include an increased risk of blood clots in the legs and lungs, which makes it unsuitable for women with a history of venous thromboembolism. It can also worsen hot flashes, which limits its appeal for women in the early years after menopause who are already dealing with vasomotor symptoms.
Why Treatment Order Matters
One of the most important shifts in osteoporosis management over the past decade is the recognition that the sequence of medications matters as much as which ones you take. The traditional approach was to start with an anti-resorptive drug like a bisphosphonate and switch to an anabolic agent only if things weren’t going well. It turns out this is backwards for high-risk patients.
Starting with an anabolic agent and then transitioning to an anti-resorptive produces substantially larger bone density gains than the reverse sequence, with the biggest differences seen at the hip.22PubMed. Treatment Sequence for Osteoporosis When patients who have been on potent bisphosphonates for a long time switch to teriparatide, hip bone density actually drops below baseline for at least the first 12 months. If they’re switching from denosumab to teriparatide, that dip can last nearly two full years.23Journal of Bone and Mineral Research. Treatment Sequence Matters: Anabolic and Antiresorptive Therapy for Osteoporosis In other words, the common practice of reserving anabolic therapy as a last resort after anti-resorptive failure is not only suboptimal — it can temporarily weaken the hip.
Combined therapy is also gaining ground. Giving teriparatide alongside denosumab appears to produce the most substantial bone density increases of any current regimen.24PubMed Central. Optimizing Sequential and Combined Anabolic and Antiresorptive Osteoporosis Therapy This combination approach is typically reserved for people with very severe osteoporosis.
Sticking With Treatment
The most effective drug in the world doesn’t help if people stop taking it, and osteoporosis medications have notoriously poor adherence. Many patients are asymptomatic until they fracture, so the motivation to keep up with a medication that doesn’t make you feel different can fade quickly.
Research consistently shows that factors like side effects, perceived effectiveness, and route of administration matter more than dosing frequency alone when it comes to whether patients stay on treatment.25PubMed. Efficacy, side effects and route of administration are more important than frequency of dosing of anti-osteoporosis treatments in determining patient adherence That said, less frequent dosing does help. Once-yearly intravenous zoledronic acid tends to have the highest persistence rates among bisphosphonates, and patients generally prefer it over weekly oral pills.26European Journal of Hospital Pharmacy. Adherence and preference of intravenous zoledronic acid for osteoporosis versus other bisphosphonates The twice-yearly denosumab injection also outperforms daily oral tablets and quarterly infusions for first-year adherence after hip fracture.27PubMed. Patients’ first-year adherence to different anti-osteoporotic therapy after hip fractures
Calcium, Vitamin D, and the Background Essentials
No osteoporosis drug works well if the raw materials for bone building aren’t available. Calcium and vitamin D supplementation alongside pharmacological therapy is recommended for optimal fracture risk reduction.28PubMed Central. The use of calcium and vitamin D in the management of osteoporosis Calcium with vitamin D together increases bone mineral density, while vitamin D on its own does not appear to have the same effect.29PubMed Central. Vitamin D and Calcium in Osteoporosis, and the Role of Bone Turnover Markers: A Narrative Review of Recent Data from RCTs
There’s an additional wrinkle worth knowing about. In postmenopausal women on anti-resorptive drugs, vitamin D supplementation has been associated with fewer gastrointestinal side effects and lower mortality, though calcium supplementation by itself did not show associations with those outcomes.30PubMed Central. Vitamin D and calcium supplementation in women undergoing pharmacological management for postmenopausal osteoporosis: a level I of evidence systematic review The upshot is that getting enough vitamin D appears to matter both for the drug’s effectiveness and for your tolerance of it.
Osteoporosis in Men
Osteoporosis is often framed as a women’s disease, but about one in four hip fractures occurs in men, and mortality after a hip fracture is actually higher in men than women. The Endocrine Society’s clinical practice guideline recommends that men at high risk of fracture be treated with approved medications, including alendronate, risedronate, zoledronic acid, and teriparatide. For men receiving androgen deprivation therapy for prostate cancer, denosumab is also approved. The choice of drug should be individualized based on fracture history, which bones are most affected, and any comorbid conditions.31The Journal of Clinical Endocrinology & Metabolism. Osteoporosis in Men: An Endocrine Society Clinical Practice Guideline – Section: Treatment
One common assumption is that testosterone replacement alone could protect men’s bones. A large trial tested this directly and found that men with low testosterone who received testosterone treatment actually had a higher fracture rate than men on placebo, with fractures occurring in about 3.5% of the testosterone group versus 2.5% of the placebo group over roughly three years.32PubMed. Testosterone Treatment and Fractures in Men with Hypogonadism That finding was unexpected and suggests that testosterone is not a substitute for actual osteoporosis medication in men who need fracture prevention.
Glucocorticoid-Induced Osteoporosis
Long-term use of corticosteroids like prednisone is one of the most common causes of secondary osteoporosis. These drugs suppress bone formation and accelerate bone loss, and fractures can occur even at bone density levels that wouldn’t normally trigger alarm. Bisphosphonates are considered the front-line choice for preventing fractures in patients on glucocorticoids, with teriparatide as a second-line option. Calcium and vitamin D should be co-prescribed in most cases.33Nature Reviews Rheumatology. Management of glucocorticoid-induced osteoporosis If you’re starting a course of steroids that’s expected to last more than three months, a conversation about bone protection should happen early rather than after damage has already accumulated.
Tracking Whether Treatment Is Working
Bone density scans are the standard way to monitor osteoporosis treatment, but they have a practical limitation: meaningful changes in bone density can take one to two years to detect. Blood markers of bone turnover offer a faster read. Markers like CTX (which reflects bone breakdown) and P1NP (which reflects bone formation) can shift within weeks to months of starting a medication, giving your doctor an early signal about whether the drug is doing its job.34PubMed. Consensus Statement on the Use of Bone Turnover Markers for Short-Term Monitoring of Osteoporosis Treatment in the Asia-Pacific Region If turnover markers haven’t budged after three to six months on an anti-resorptive, that can flag an adherence problem or a need to switch medications, rather than waiting a year or more for a repeat bone density scan to deliver bad news.
These markers are especially useful for anabolic agents, where you’d expect P1NP to rise sharply in the first few months. A flat response might mean the drug isn’t being absorbed properly or that it’s being blunted by a prior anti-resorptive, which circles back to why treatment sequencing matters so much.