Fosamax Regret, Stopping, and Restarting: What Real Patients and Clinical Data Actually Show

Why Patients Regret Stopping Fosamax

Many people quit alendronate and feel fine for months, then start second-guessing themselves when a follow-up DXA scan shows bone density sliding back down. That pattern is common enough to have a name in clinical practice: post-discontinuation anxiety.

The Fear That Drives Discontinuation

The two fears that push most patients off alendronate are osteonecrosis of the jaw (ONJ) and atypical femoral fracture (AFF). Both are real. Both are also statistically rare in the oral, low-dose osteoporosis setting.

The FDA updated alendronate labeling in 2011 to include AFF warnings after case reports accumulated. A 2014 Swedish cohort study published in the New England Journal of Medicine (N=1.7 million patient-years) estimated the absolute risk of AFF at roughly 11 cases per 100,000 person-years during the first two years of bisphosphonate use, rising to 119 per 100,000 person-years after 8 or more years of use [1]. That number sounds alarming in isolation. Set against the background fracture risk in a 70-year-old woman with a T-score of , 2.8, it is not a reason to stop at year two.

ONJ risk in patients taking oral bisphosphonates for osteoporosis (as opposed to the higher IV doses used in cancer) is estimated at 0.001% to 0.01% per year by the American Association of Oral and Maxillofacial Surgeons [2].

What Reddit and Patient Forums Actually Say

Patient communities on Reddit (r/osteoporosis) and Drugs.com review threads show a consistent pattern. Patients who stopped after one to two years because of GI problems often report relief from symptoms but worry within six to twelve months when they read about fracture risk. Patients who stopped after five or more years on a physician-recommended drug holiday tend to report feeling reassured by the concept of residual drug effect. A smaller subset stopped after an AFF diagnosis and describe significant regret that they were not monitored more closely for thigh pain during treatment. That monitoring gap is a real clinical failure worth naming directly.

What Happens to Bone After You Stop Alendronate

Alendronate binds tightly to hydroxyapatite in bone mineral and has an estimated skeletal half-life of more than ten years [3]. This means the drug does not simply disappear when you swallow your last tablet.

Bone Turnover Marker Rebound

Serum markers of bone resorption, specifically C-terminal telopeptide (CTX) and N-terminal telopeptide (NTX), begin rising within three to six months of stopping alendronate. By twelve months, they may return to pre-treatment levels in some patients [4]. This biochemical rebound does not immediately translate to fracture risk, but it signals that the skeleton is no longer in the suppressed-remodeling state that alendronate creates.

Bone Mineral Density Decline

The FLEX trial (Fracture Intervention Trial Long-Term Extension, N=1,099) is the landmark dataset here. Women who had taken alendronate for five years and then were randomized to placebo lost approximately 2 to 3% of femoral neck BMD over the next five years, compared with those who continued the drug [5]. Spine BMD losses were smaller. Hip fracture rates did not differ significantly between the groups in the overall FLEX population, but the subgroup with a femoral neck T-score <, 2.5 at the time of discontinuation did show higher fracture rates in the placebo arm [5].

The Residual Fracture Protection Window

Based on FLEX data and pharmacokinetic modeling, most guidelines accept that residual fracture protection after stopping alendronate persists for approximately one to three years in patients who completed three to five years of therapy [6]. After that window, protection wanes. This is why the drug holiday concept has a defined endpoint, not an indefinite free pass.

Clinical Guidelines on Drug Holidays

The American Society for Bone and Mineral Research (ASBMR) 2016 Task Force issued the most widely cited guidance on bisphosphonate drug holidays. Their position: "After 5 years of oral bisphosphonate treatment, reassess fracture risk. For patients at high risk, continue treatment. For patients at lower risk, a drug holiday of 2 to 3 years may be appropriate." [6]

The Endocrine Society's 2019 Pharmacological Management of Osteoporosis guideline similarly recommends that after three to five years of oral bisphosphonate therapy, clinicians stratify patients by fracture risk before deciding whether to continue, switch agents, or observe [7]. High-risk features include prior hip or vertebral fracture, femoral neck T-score <, 2.5, or age above 75.

Who Should Not Take a Drug Holiday

Some patients are not good candidates for any break from therapy. These include individuals who fractured during treatment, those with T-scores that remain severely below normal, and patients on glucocorticoids who developed secondary osteoporosis. The ASBMR task force specifically flagged that "patients with a prior hip or spine fracture or with femoral neck T-score <, 2.5 at the time of reassessment should generally continue bisphosphonate therapy or switch to an alternative agent" [6].

Duration of Drug Holidays

For patients who do qualify for a holiday, the ASBMR recommendation is a maximum of two to three years, then repeat DXA. If T-score has declined significantly or a new fracture has occurred, restart or switch agents. Waiting longer than three years without reassessment is not supported by current evidence.

When Restarting Alendronate Makes Sense

Restarting alendronate after a drug holiday is straightforward if the patient tolerated it before. The bone is still loaded with drug from prior treatment, so the pharmacological environment differs from a true treatment-naive start. Repeat DXA response timelines are similar: expect six to twelve months before BMD gains are detectable on densitometry.

Triggers for Restarting

The clearest triggers for restarting are a new fragility fracture during the holiday, a DXA showing T-score decline back to or below , 2.5, or a significant rise in bone turnover markers (CTX above the premenopausal reference range). Some clinicians also restart if the patient's clinical risk factors have worsened, for example a new fall history or new corticosteroid use.

Alternatives to Restarting Alendronate

If the patient stopped because of GI intolerance, options include switching to intravenous zoledronic acid (Reclast, 5 mg once yearly), which bypasses the GI tract entirely. The HORIZON-PFT trial (N=7,736) showed that zoledronic acid reduced vertebral fracture risk by 70% and hip fracture risk by 41% versus placebo over three years [8]. For patients with very high fracture risk, anabolic agents like teriparatide (Forteo, 20 mcg/day subcutaneous) or romosozumab (Evenity) may be more appropriate than restarting a bisphosphonate.

Real Patient Experiences: What the Data Behind the Reviews Show

Patient-reported outcomes from structured databases give a more reliable signal than any single Reddit thread. Drugs.com aggregates thousands of alendronate ratings. As of 2024, the average rating sits at approximately 5.8 out of 10, with GI effects and fear of side effects driving most negative reviews. Patients who report positive experiences tend to describe concrete DXA improvements, for example moving from T-score , 3.1 to , 2.4 after two years.

The GI Problem Is Solvable

Alendronate requires strict dosing protocol: taken with 6 to 8 ounces of plain water, no other food or drink for 30 minutes, and remaining upright for at least 30 minutes. Esophageal irritation rates drop substantially with proper technique. A 2000 study in the American Journal of Gastroenterology (N=241) found that upper GI adverse events were significantly more common when patients deviated from the standard dosing instructions [9]. Patients who stopped because of heartburn without first trying correct technique may have stopped unnecessarily.

Patients Who Never Should Have Been on It

Some of the strongest regret stories come from patients who received alendronate without meeting threshold criteria. The National Osteoporosis Foundation and USPSTF recommend treatment for women with T-scores <, 2.5 or T-scores between , 1.0 and , 2.5 with a 10-year major osteoporotic fracture probability at or above 20% by FRAX [10]. Prescribing to patients below these thresholds exposes them to side effect risk without meaningful fracture benefit.

Positive Outcomes That Get Less Attention

The FIT trial (Fracture Intervention Trial, N=2,027 for the vertebral fracture arm) demonstrated that alendronate reduced the relative risk of new vertebral fractures by 47% over three years [11]. That magnitude of risk reduction gets lost in side-effect-focused online discussions. For a patient with established osteoporosis and a prior compression fracture, that 47% reduction is not a small number.

Monitoring Checklist for Patients on or Restarting Alendronate

Structured monitoring reduces both regret and missed complications.

• Baseline labs before starting: serum calcium, 25-hydroxyvitamin D, creatinine. Correct vitamin D deficiency (target 25-OH-D at or above 30 ng/mL) before initiating therapy.
• Calcium and vitamin D co-supplementation: most guidelines recommend 1,000 to 1,200 mg elemental calcium daily (dietary preferred) and 600 to 800 IU vitamin D daily at minimum during therapy.
• DXA timing: repeat DXA at one to two years after starting or restarting to confirm response. A BMD gain of 3% or more at the spine is generally considered a meaningful response.
• Thigh pain surveillance: ask about new groin or thigh pain at every visit. This is the prodromal symptom of AFF. If present, obtain bilateral femur X-rays before continuing the drug.
• Dental review: inform your dentist you are on a bisphosphonate before any invasive dental procedures. Elective extractions or implants should ideally be completed before starting long-term bisphosphonate therapy.
• Bone turnover markers: CTX drawn fasting in the morning can confirm biochemical response within three to six months of starting or restarting.

The Atypical Femur Fracture: Putting the Risk in Perspective

AFF deserves its own section because fear of it drives a large fraction of unsupervised discontinuations.

How Common Is AFF Really

The absolute numbers matter here. A 2011 FDA Drug Safety Communication estimated the risk of AFF at 1.78 per 100,000 person-years among bisphosphonate users [12]. Hip fracture incidence in untreated women aged 65 to 69 with osteoporosis is roughly 10 times higher than that. The net fracture benefit of alendronate in the appropriate population substantially outweighs the AFF risk, particularly in the first five years of use.

Warning Signs to Know

AFF almost always presents with prodromal thigh pain before the complete fracture. Bilateral femur X-rays showing cortical thickening or a "beaking" pattern on the lateral cortex are diagnostic clues. If caught at this stage, the drug can be stopped and prophylactic intramedullary nailing considered, avoiding a complete fracture. Teriparatide has been used post-AFF to support healing, with some case-series evidence suggesting benefit [13].

Choosing Between Continuing, a Holiday, or Switching Agents

The decision tree is not complicated when laid out cleanly.

After 3 to 5 years of alendronate: assess T-score, fracture history, and bone turnover markers. If T-score at femoral neck remains <, 2.5, or prior hip or vertebral fracture exists, continue therapy or switch to zoledronic acid. If T-score is between , 1.0 and , 2.5 with no prior fracture, a two-to-three year drug holiday is reasonable with DXA repeat at the end. If the patient has very high fracture risk (multiple vertebral fractures, T-score <, 3.0), consider anabolic therapy before cycling back to a bisphosphonate.

The Endocrine Society's 2019 guideline notes that "after bisphosphonate treatment is discontinued, antiresorptive effects may persist for months to years depending on the agent and the duration of prior treatment" [7]. That pharmacological reality is the entire rationale for the drug holiday concept.

The FLEX trial subgroup data remain the clearest clinical anchor: patients with a femoral neck T-score <, 2.5 at the time of stopping had a significantly higher rate of clinical fracture during the subsequent five-year placebo period compared with those who continued [5]. If your T-score is still low, stopping is the higher-risk choice.