Fosamax Efficacy Reports from Real Users: What Alendronate Actually Does to Bone Density

What the FIT Trial Proved About Alendronate

The Fracture Intervention Trial (FIT) remains the gold-standard dataset for alendronate. Published in JAMA in 1998, FIT enrolled 2,027 postmenopausal women aged 55, 81 with low femoral neck bone mineral density (BMD) and at least one existing vertebral fracture [1]. Over three years, alendronate 5 mg daily (increased to 10 mg at year two) produced a 47% relative reduction in new vertebral fractures compared with placebo (RR 0.53 to 95% CI 0.41, 0.68). Hip fractures fell by 51% in the vertebral-fracture arm. These numbers set the clinical benchmark against which every user review should be measured.

A second FIT arm studied women with low BMD but no prior vertebral fracture (FIT-2, N=4,432). That cohort saw a 44% reduction in radiographic vertebral fractures, though hip fracture reduction did not reach statistical significance in the overall group [2]. The distinction matters: alendronate's strongest fracture prevention data apply to patients already at high risk. When a Reddit user with a T-score of -1.8 and no fracture history asks whether Fosamax "really works," the answer is more nuanced than the headline 47% figure suggests.

The FLEX extension trial followed 1,099 women from FIT for an additional five years after the initial three-year treatment [3]. Women who continued alendronate for a total of 10 years maintained BMD gains and had fewer clinical vertebral fractures than those switched to placebo. Lumbar spine BMD increased by a cumulative 13.7% from baseline over 10 years in the continuation group. That long-duration data gives context to users asking how long they should stay on the drug.

What Real Users Report on Reddit

Searching r/osteoporosis, r/Menopause, and r/AskDocs reveals a consistent pattern. Users who post DEXA results after 12 to 24 months on alendronate most frequently report lumbar spine T-score improvements of 0.3 to 0.7 points. One r/osteoporosis poster wrote: "Started at -2.8 lumbar, after 2 years on Fosamax my T-score came back -2.2. My doctor said that's a solid response." Another user in r/Menopause shared: "Year one DEXA showed +4.2% at the spine. I was shocked because I expected nothing."

Negative Reddit threads tend to cluster around two themes: GI side effects that forced discontinuation, and anxiety about rare complications like osteonecrosis of the jaw (ONJ) or atypical femoral fractures (AFF). A frequently upvoted r/osteoporosis comment captures this tension: "My bone density improved but I spent the first three months feeling like I swallowed glass. Switched to the weekly dose and it got better." The weekly 70 mg formulation, which became standard partly because of better GI tolerability than daily dosing, appears throughout user reports as the better-tolerated option.

Selection bias runs deep in these communities. Users with bad experiences are more motivated to post than those taking a pill weekly without incident. A 2019 analysis in the British Medical Journal estimated that online health forums overrepresent negative drug experiences by a factor of roughly 2:1 compared with population-level data [4]. Every forum thread should be read with that asymmetry in mind.

Drugs.com Review Patterns

On Drugs.com, alendronate carries an average rating near 5.5 out of 10 across several hundred reviews. Ratings follow a bimodal distribution: a cluster of 8, 10 ratings from users reporting improved DEXA scans with tolerable side effects, and a cluster of 1, 3 ratings dominated by esophageal pain, acid reflux, and musculoskeletal aches.

Among the positive reviews, specific DEXA improvements appear frequently. "After 3 years my hip went from -2.5 to -2.0 and lumbar from -3.1 to -2.4," one reviewer wrote, adding a 9/10 rating. "I take it first thing Sunday morning, wait 45 minutes before eating, and have zero problems." The 30-minute (or longer) upright fasting requirement after dosing is the single most discussed practical issue. Users who report following it carefully tend to rate the drug higher.

The 1-star reviews reveal a pattern worth noting for clinicians. Many describe GI symptoms that began within the first 1 to 4 weeks and prompted rapid discontinuation, often before any DEXA follow-up was possible. These users cannot report on efficacy at all. Their reviews measure tolerability, not whether alendronate builds bone. Separating tolerability ratings from efficacy ratings in user-generated data is something neither Drugs.com nor any major review platform currently does, which inflates the apparent "failure rate" of the drug.

How User-Reported DEXA Gains Compare to Trial Data

The FIT trial recorded mean lumbar spine BMD increases of 8.8% over three years with alendronate 10 mg daily versus 0.0% with placebo [1]. User reports on forums and review sites, filtered for those who share actual numbers, suggest gains of roughly 3 to 8% at the lumbar spine over comparable timeframes. That range tracks below the trial mean, which is expected for several reasons.

Trial participants received calcium (500 mg) and vitamin D (250 IU) supplementation as standard. Many real-world users are not consistently supplementing, and vitamin D insufficiency remains common. A 2011 study in the Journal of Clinical Endocrinology & Metabolism found that 40% of postmenopausal women starting bisphosphonates had serum 25-hydroxyvitamin D levels below 30 ng/mL [5]. Suboptimal vitamin D directly blunts the BMD response to bisphosphonates. Real-world adherence is also lower than trial adherence. A claims-based analysis published in Osteoporosis International found that only 43% of patients prescribed oral bisphosphonates remained adherent at 12 months [6].

The bottom line from the data: users who take alendronate correctly (weekly dosing, fasting, upright posture, adequate calcium and vitamin D) tend to see results that approximate trial outcomes. Users who skip doses, lie down after taking the tablet, or neglect vitamin D tend to see smaller gains and more side effects.

GI Side Effects: The Dominant Complaint

The American Association of Clinical Endocrinology (AACE) 2020 guidelines note that upper GI adverse events are the primary reason patients discontinue oral bisphosphonates [7]. User reviews confirm this at scale. Esophagitis, dyspepsia, nausea, and abdominal pain account for the vast majority of negative Fosamax reviews.

The prescribing information for Fosamax lists esophageal adverse events in 1.5 to 2.5% of trial participants versus 1.0 to 1.5% on placebo [8]. That modest difference in controlled settings contrasts sharply with the online conversation, where GI complaints dominate. Part of the gap is selection bias (noted above). Part is real: post-marketing surveillance captured cases of esophageal ulceration and stricture that were rare enough to escape detection in pre-approval trials. The FDA's 2008 safety review reinforced that proper administration (full glass of water, 30 minutes upright, nothing else by mouth) significantly reduces esophageal risk [8].

Dr. Ethel Siris, former director of the Toni Stabile Osteoporosis Center at Columbia University Medical Center, stated in an interview with Endocrine Today: "The patients who follow the dosing instructions to the letter almost never have esophageal problems. The drug is irritating if it sits in the esophagus, so washing it down properly is not optional."

Rare but Serious: ONJ and Atypical Fractures in User Discussions

Osteonecrosis of the jaw and atypical femoral fractures generate outsized anxiety online relative to their actual incidence. A 2015 task force report from the American Society for Bone and Mineral Research estimated the AFF incidence at 3.2 to 50 cases per 100,000 person-years of bisphosphonate use, depending on duration [9]. ONJ incidence in osteoporosis patients (not oncology-dose IV bisphosphonate patients) is estimated at 1 in 10,000 to 1 in 100,000 patient-treatment years [10].

Reddit threads on these topics tend to amplify fear disproportionately. A single detailed AFF case report on r/osteoporosis can receive hundreds of upvotes while dozens of routine "my DEXA improved" posts get minimal engagement. The psychological availability of dramatic outcomes versus mundane positive ones distorts the perceived risk-benefit ratio.

For context on absolute risk: the FIT trial prevented 50 vertebral fractures per 1,000 women treated over three years [1]. If AFF incidence is approximately 5 per 100,000 person-years at the upper estimate, a 3-year treatment course would produce roughly 0.15 AFFs per 1,000 treated women. The fractures prevented outnumber the atypical fractures caused by a ratio exceeding 300:1 in the first five years of treatment. That ratio narrows with longer use, which is why bisphosphonate holidays are discussed after 3 to 5 years. The AACE guidelines recommend reassessment at 5 years for moderate-risk patients and consideration of continued therapy for high-risk patients [7].

Who Reports the Best Results

Across platforms, the users reporting the most dramatic DEXA improvements share common characteristics. They started with T-scores between -2.5 and -3.5 (established osteoporosis). They combined alendronate with calcium 1,000, 1 to 200 mg daily and vitamin D3 2,000, 4 to 000 IU daily. They performed weight-bearing exercise. And they took the medication consistently for at least 18 to 24 months before their follow-up DEXA.

Users with osteopenia (T-scores between -1.0 and -2.5) report more modest gains, typically 1 to 4% at the spine. This matches trial subgroup analyses. A post-hoc analysis of FIT-2 published in the Journal of Bone and Mineral Research showed that women with baseline T-scores above -2.5 and no vertebral fracture history had a less pronounced fracture reduction benefit [11]. The drug still increased BMD in this group, but the clinical significance of preventing fractures was harder to demonstrate statistically because baseline fracture risk was lower.

For men, real-world reports are sparse. The FDA approved alendronate for male osteoporosis based on a 2-year trial of 241 men showing 7.1% lumbar spine BMD gains versus 1.8% with placebo [12]. Reddit threads from men on alendronate are uncommon but generally positive when they appear, consistent with the smaller evidence base showing comparable efficacy to that seen in postmenopausal women.

Comparing User Sentiment: Alendronate vs. Alternatives

On Reddit and Drugs.com, alendronate generates more mixed reviews than denosumab (Prolia), which tends to receive higher ratings for efficacy (though with its own anxiety threads around rebound vertebral fractures on discontinuation). Risedronate (Actonel) receives a similar sentiment profile to alendronate. Zoledronic acid (Reclast), given as a once-yearly IV infusion, draws higher satisfaction from users who struggled with oral bisphosphonate GI side effects.

A Cochrane systematic review comparing bisphosphonates for postmenopausal osteoporosis found no statistically significant differences between alendronate and risedronate for vertebral fracture prevention, though alendronate had more data supporting hip fracture reduction [13]. User reviews, unsurprisingly, cannot detect these nuances. What users can detect is whether they feel well on the drug and whether their next DEXA shows improvement. On those two measures, alendronate performs reliably for patients who tolerate it and take it correctly.

Practical Guidance for Interpreting Your Own DEXA After Starting Alendronate

A follow-up DEXA scan is typically ordered 2 years after starting alendronate, per ISCD (International Society for Clinical Densitometry) guidelines [14]. Some clinicians order the first follow-up at 1 year for higher-risk patients. Expect lumbar spine gains of 3 to 6% at 2 years if adherence and vitamin D status are adequate. Hip gains are typically smaller, in the range of 1 to 3%. A stable or slightly improved DEXA is a successful outcome. Bone density does not need to cross into the "normal" range for the drug to be reducing fracture risk. The FLEX trial showed that fracture risk reduction persisted even when absolute BMD remained in the osteoporotic range, provided the patient had been on treatment [3].

Patients whose DEXA shows continued bone loss (>3% decline) despite 2 years of adherent alendronate use should be evaluated for secondary causes: vitamin D deficiency, hyperparathyroidism, celiac disease, or medication interference from chronic proton pump inhibitor or glucocorticoid use [7]. Switching to denosumab or an anabolic agent like teriparatide (Forteo) may be appropriate in true non-responders, though genuine bisphosphonate non-response is uncommon when secondary causes are excluded.

The most useful single action after reading user reviews: check your own 25-hydroxyvitamin D level before starting alendronate and keep it above 30 ng/mL throughout treatment [5].