Fosamax Efficacy Reports from Real Users: What Alendronate Actually Does to Bone Density
Alendronate sodium (brand name Fosamax) is an oral bisphosphonate approved by the FDA in 1995 for the treatment and prevention of postmenopausal osteoporosis, and later for osteoporosis in men and glucocorticoid-induced osteoporosis. It is dosed as a 70 mg once-weekly tablet or a 10 mg daily tablet, and is available as a generic. This article does not report new data. It compares what patients say about Fosamax in online reviews and forums with what controlled trial evidence actually established, and it explains why the two sources of information often disagree.
The direct answer
Alendronate has controlled-trial evidence, going back to the pivotal Fracture Intervention Trial (FIT) in the 1990s, for reducing vertebral and hip fractures in postmenopausal women with low bone density, particularly those who already had a vertebral fracture. Online user reports (Reddit, Drugs.com) are dominated by two unrelated signals that get conflated: gastrointestinal tolerability, which drives most negative reviews, and self-reported DEXA change, which tracks roughly with trial-level bone density gains only among users who describe taking the drug on an empty stomach, remaining upright afterward, and maintaining adequate vitamin D. A negative online review usually reflects early discontinuation for GI symptoms, not a failure of the drug to build bone. Verification against the original trial publications is recommended before quoting exact percentages to a patient, because several of the specific figures commonly repeated online (including in prior versions of this page) trace to secondary summaries rather than to a checked primary source.
Evidence boundary: what is established, what is not
Established (FDA label, widely cited trial evidence, and current guideline documents): alendronate increases lumbar spine and hip bone mineral density relative to placebo in postmenopausal women with osteoporosis; large randomized trial data from the 1990s (the FIT program) support reduced vertebral and hip fracture risk in women with pre-existing vertebral fractures and low bone density; upper gastrointestinal irritation, including esophagitis, is a recognized adverse effect tied to administration technique; atypical femoral fractures and osteonecrosis of the jaw are recognized but uncommon risks associated with long-term bisphosphonate use, discussed in FDA safety communications.
Plausible but not rigorously quantifiable from this source base: the exact magnitude of BMD gain a typical online reviewer should expect at a given time point, since forum posts are self-selected, self-reported, and not independently verified against a DEXA report; the precise ratio of GI complaints online versus in trial populations, since forum posting behavior is not randomly sampled.
Not established here: any claim that a specific percentage of forum users overrepresent negative experiences by a fixed ratio, or that a named academic quoted a specific sentence about dosing adherence. Both appeared in earlier drafts of this material and could not be verified against a primary source, so they have been removed rather than repeated.
What the FIT trial is understood to have shown
The Fracture Intervention Trial enrolled postmenopausal women with low femoral neck bone density, one arm with an existing vertebral fracture and a second arm without one. The trial is widely cited in FDA labeling and osteoporosis guidelines as the basis for alendronate's fracture-prevention indication: a large relative reduction in new vertebral fractures, and a meaningful reduction in hip fractures, over roughly three years, concentrated in women who already had a vertebral fracture at baseline. The trial's own extension study reportedly followed a subset of participants for up to ten years and found that women who continued treatment maintained bone density gains and had somewhat lower rates of new vertebral fractures than women switched to placebo.
For current regulatory and safety status, FDA postmarket drug safety communications on bisphosphonates are the primary reference and should be checked directly:
What appears in Reddit and Drugs.com discussions
Reviewing threads on r/osteoporosis, r/Menopause, and Drugs.com's alendronate review page shows a recurring pattern rather than a set of verifiable data points. Users who report a follow-up DEXA scan after roughly one to three years on alendronate most often describe a lumbar spine improvement, sometimes framed as a T-score change of a few tenths of a point. Users who report stopping the drug early almost always cite gastrointestinal symptoms, most commonly a burning or irritated feeling in the chest or upper abdomen that began within the first few weeks.
No individual quotation from these threads is reproduced here. Forum posts are unverified, cannot be independently confirmed, and attributing a specific sentence to an anonymous account risks presenting invented or misremembered text as evidence. The honest summary is: positive reports cluster around users who describe correct administration technique (weekly dosing, full glass of water, staying upright, waiting before eating) and supplementation with calcium and vitamin D; negative reports cluster around early GI discontinuation, which by definition happens before a follow-up DEXA could show any bone effect.
Drugs.com's published aggregate rating for alendronate has historically skewed toward the low-to-middle range, which likely reflects this same asymmetry: a person who tolerates a once-weekly pill without incident has less reason to write a review than a person who had a bad reaction. This selection effect is a known limitation of drug review sites generally, not unique to alendronate, and no specific numeric bias ratio should be quoted without checking the underlying methodology of whatever study is cited for it.
Why online DEXA reports and trial DEXA results are hard to compare directly
Several structural differences make forum-reported bone density changes an unreliable stand-in for trial results:
Trial participants received protocol-mandated calcium and vitamin D supplementation and were monitored for adherence. Real-world users are not. Vitamin D insufficiency is common in postmenopausal populations and is understood to blunt the bone response to bisphosphonate therapy, though this page does not have a verified source for an exact prevalence figure and none is quoted here.
Trial adherence was tracked and enforced through the study protocol. Real-world persistence with weekly oral bisphosphonates is known from health-services literature to decline substantially within the first year, though again, an exact adherence percentage should be checked against a specific, verified source rather than repeated from memory.
Forum posters who report a DEXA number have, by definition, stayed on the drug long enough to get one. Anyone who quit in the first month for GI reasons is systematically excluded from the "did it work" conversation, which inflates the apparent efficacy rate among people who do post outcome updates and simultaneously inflates the apparent side-effect rate among the broader posting population.
Side effects: what drives the negative reviews
Upper gastrointestinal symptoms, including esophageal irritation, reflux, and stomach discomfort, are the most consistently reported reason people say they stopped alendronate or rate it poorly online. The FDA-approved label documents esophageal irritation as a known risk, particularly with incorrect administration, and recommends taking the tablet with a full glass of plain water first thing in the morning, remaining upright for at least 30 minutes, and avoiding food, other medications, or supplements during that window. The switch from a daily to a weekly dosing schedule was intended in part to improve gastrointestinal tolerability, and weekly dosing is now the standard approach.
Rare but serious risks, osteonecrosis of the jaw and atypical femoral fracture, generate a disproportionate amount of attention in online discussion relative to their frequency. Both are recognized in FDA safety communications on bisphosphonates as uncommon events associated with bisphosphonate use, more so with longer duration of therapy and, for osteonecrosis of the jaw, more so at the much higher intravenous doses used in cancer treatment than at osteoporosis doses. A single detailed personal account of either complication tends to be shared and discussed far more than routine positive updates, which distorts how common these events feel relative to how common they actually are. Patients with concerns about either risk should raise them directly with the prescribing clinician rather than relying on forum prevalence estimates, which are not a substitute for the incidence data in the FDA label and safety communications linked above.
When online "it didn't work for me" reports likely reflect something else
Genuine non-response to alendronate, meaning a patient who takes it correctly, has adequate vitamin D, and still loses bone density, is considered uncommon in clinical practice. A negative DEXA trend during alendronate treatment is more often explained by one of the following, each of which is a matter for clinical evaluation rather than something a forum comment can diagnose:
- Inconsistent dosing or incorrect administration (not staying upright, eating too soon)
- Undiagnosed vitamin D deficiency
- Secondary causes of bone loss, such as hyperparathyroidism or celiac disease
- Ongoing use of medications that interfere with bone metabolism, such as chronic glucocorticoids
- Simply not enough elapsed time; DEXA changes at the hip in particular can be slower to appear than at the spine
This is general information, not an individual diagnosis. A patient whose DEXA shows a meaningful decline on treatment should be evaluated by the prescribing clinician, not reassured or alarmed by a forum thread.
A framework for reading a Fosamax efficacy report
Use this to sort any individual review, forum post, or personal anecdote about alendronate into what it can and cannot tell you.
| What the report claims | Reported experience (forum/review) | Controlled evidence (trial data) | What can be concluded |
|---|---|---|---|
| "My DEXA improved" | Self-reported, unverified, self-selected posters | FIT trial documented measurable BMD gains at the lumbar spine over multiple years in a randomized, monitored population | Directionally consistent, but the individual number should not be generalized; ask whether the poster reports correct administration and vitamin D status |
| "Fewer fractures" | Almost never reported by individuals, since fracture prevention is a population-level outcome | This is the trial's actual primary endpoint and its strongest evidence base | Trust the trial evidence here, not anecdote; no individual review can demonstrate fracture prevention |
| "It gave me bad heartburn / GI pain" | Dominant theme in negative reviews | Label-documented risk, more common with incorrect administration | Believable and actionable; check administration technique before assuming the drug itself is intolerable |
| "It caused a rare fracture / jaw problem" | Rare but disproportionately visible online | Documented in FDA safety communications as uncommon, more so with longer duration | Take seriously enough to discuss with a prescriber, but do not let a single dramatic post override the low absolute incidence in official safety data |
| "It didn't work at all" | Common phrase, rarely defined | Genuine non-response is considered uncommon when the drug is taken correctly | Investigate adherence, technique, vitamin D, and secondary causes before concluding the drug failed |
Decision rule: if an online report describes a tolerability problem (GI symptoms, early discontinuation), treat it as informative about the administration experience but silent on efficacy. If it describes an efficacy claim (DEXA change, fracture), treat it as a single unverified data point that only becomes meaningful in combination with your own DEXA history, vitamin D level, and your prescriber's assessment, not as evidence that generalizes to a stranger reading it online.
Practical next step, not a diagnosis
Before drawing any conclusion from online reviews, positive or negative, about whether Fosamax will work for you: confirm the correct administration technique with your prescriber or pharmacist, check a serum 25-hydroxyvitamin D level if it has not been checked recently, and ask when your next DEXA scan is planned (commonly one to two years after starting therapy, though timing depends on individual risk). If you are experiencing esophageal pain, chest pain, difficulty swallowing, or jaw pain, contact your prescriber promptly rather than waiting for a scheduled follow-up; severe or worsening esophageal symptoms warrant urgent evaluation.
Frequently asked questions
Frequently asked questions
Does Fosamax actually work?
Why are Fosamax reviews online so negative?
How long does it take to see a bone density change on alendronate?
What should I do if Fosamax upsets my stomach?
Is a rare side effect like jaw osteonecrosis or atypical fracture a reason to avoid alendronate?
References and further verification
- FDA, Drug Safety and Availability: https://www.fda.gov/drugs/drug-safety-and-availability
- For the Fracture Intervention Trial (FIT), FIT-2, and FLEX extension study, and for FDA labeling details on adverse event rates, verify the exact publication and figures directly through PubMed or the current FDA-approved prescribing information before citing specific numbers clinically. This article intentionally avoids repeating exact citation identifiers that could not be confirmed as accurate.
This article is intended for general education and has not yet completed qualified medical review. It does not replace individualized medical advice. If you are experiencing severe chest pain, difficulty swallowing, jaw pain, or a suspected fracture, seek prompt medical evaluation.