Most people take Fosamax (alendronate) for five years before their doctor reassesses whether to continue or pause treatment. For those at higher risk of fractures, guidelines recommend staying on it for at least 10 years. The answer depends on your fracture risk, bone density, and how your body responds to the medication.
The Standard Five-Year Reassessment
Clinical guidelines recommend reassessing fracture risk after five years of oral bisphosphonates like Fosamax. At that point, your doctor will typically order a bone density scan and evaluate whether you’ve met your treatment goals. If your bone density has improved and your fracture risk is moderate, you may be a candidate for a treatment pause. If your risk remains high, continuing treatment is the better option.
A 2024 position statement from the American Society for Bone and Mineral Research reinforced that a pause in bisphosphonate therapy, often called a “drug holiday,” may be considered once treatment targets are reached. But the statement also emphasized that more information is still needed to define the ideal timeline for balancing long-term benefits against rare side effects.
Who Should Stay on It Longer
Some people benefit from taking Fosamax for 10 years or more. The National Osteoporosis Guideline Group identifies several groups where longer treatment is strongly recommended:
- Age 70 or older when first starting the medication
- Previous hip or spinal fracture
- Long-term steroid use (such as prednisone for inflammatory conditions)
- Fractures that occur during the first five years of treatment
Post-hoc analyses from extension studies also suggest that women with very low hip bone density (a T-score below negative 2.5) are most likely to benefit from continuing beyond five years. If you fall into any of these categories, the risk of stopping treatment typically outweighs the risk of continuing it.
Why a Drug Holiday Works
Fosamax doesn’t leave your body the way most drugs do. It binds directly into bone tissue and has an extremely long skeletal half-life. Research shows that bone density can remain stable for up to three years after stopping the drug, because the medication stored in your bones continues to suppress the cells that break bone down. One study found that bone-resorbing cells remained suppressed in over 91% of patients even after a drug holiday of less than three months, and roughly 75% of patients still showed suppressed activity after six months off the drug.
This lingering effect is exactly why a drug holiday is possible with bisphosphonates but not with other osteoporosis medications. The ASBMR’s 2024 guidance notes that bone loss after stopping bisphosphonates is much slower than after stopping all other osteoporosis treatments, making Fosamax uniquely suited to planned breaks.
How Long a Drug Holiday Lasts
For alendronate specifically, UK prescribing guidance recommends a drug holiday of about two years before restarting. Other bisphosphonates have different timelines: risedronate and ibandronate holidays last about one year, while the injectable form (zoledronic acid) allows a three-year pause. During the holiday, your doctor will monitor your bone density and may check blood or urine markers that reflect how actively your bones are breaking down.
There is no universal consensus on when exactly to restart. Some experts recommend resuming treatment when bone turnover markers rise back to pre-treatment levels, signaling the drug’s protective effect is wearing off. Others rely on a meaningful drop in bone density on a follow-up scan. The Agency for Healthcare Research and Quality has acknowledged that despite widespread use of drug holidays, there is no agreement on how long they should last, how they should be monitored, or the exact criteria for restarting therapy. In practice, the decision is individualized.
Rare Risks With Long-Term Use
The two side effects that drive the conversation about treatment duration are both rare but serious: jaw bone damage and unusual thigh fractures.
Osteonecrosis of the jaw, where a section of jawbone loses its blood supply and deteriorates, occurs in less than 0.1% of people taking oral bisphosphonates for osteoporosis. It most commonly develops after invasive dental procedures like tooth extractions. Some dental guidelines recommend stopping bisphosphonates two to three months before such procedures, though evidence that this actually reduces risk is limited.
Atypical femoral fractures, stress fractures in the thigh bone that occur with minimal trauma, are the more duration-dependent concern. For the first couple of years of treatment, the rate is roughly 1.8 per 100,000 patients per year. After eight to ten years of continuous use, that rate climbs to about 113 per 100,000 per year. This steep increase over time is the primary reason guidelines recommend reassessment rather than indefinite use. Importantly, these fractures often produce warning signs like dull thigh or groin pain weeks before a full break occurs, so reporting new thigh pain to your doctor matters.
What Happens After Fosamax
If you stop Fosamax after reaching your treatment goals, the stored medication continues working for a while, but it doesn’t last forever. Your doctor will schedule periodic bone density scans to watch for significant decline. If bone density drops meaningfully or you experience a new fracture, restarting treatment is typically the next step.
For people who were previously on a different class of osteoporosis medication and then switched to Fosamax, the bisphosphonate can serve as a “maintenance” treatment to lock in bone density gains. Research has shown that even periodic dosing of bisphosphonates, rather than continuous daily or weekly pills, may be enough to maintain bone density targets over the long term. This is an active area of clinical discussion, and your treatment plan will likely evolve as your bone health changes with age.