Fosamax (Alendronate) Regret, Stopping, and Restarting: What Women Actually Experience

Why Women Stop Fosamax, and Whether They Regret It

Most women who stop Fosamax do so for one of three reasons: GI side effects that make weekly dosing miserable, fear of rare but widely publicized complications such as jaw necrosis or atypical fractures, or a sense that five-plus years is "long enough." A smaller group stops because a prescriber tells them to take a drug holiday.

Regret surfaces when a follow-up DEXA scan shows bone density dropping again, or when a fragility fracture happens after stopping. On Reddit threads tagged r/osteoporosis, a recurring pattern appears: women describe stopping after two or three years because of heartburn, then seeing their T-score worsen a year or two later and wishing they had pushed through the GI issues or switched to a different formulation.

The clinical picture is more nuanced. Whether stopping was medically justifiable depends almost entirely on where your T-score sat at the time you stopped and how long you had taken the drug before stopping.

The GI Complaint That Drives Most Discontinuation

Upper GI events, including esophageal irritation, acid reflux, and nausea, are the leading reason women stop alendronate before a planned drug holiday. Studies estimate that up to 17 to 20% of patients discontinue alendronate within the first year due to GI intolerance. The twice-daily 5 mg formulation carries a higher GI burden than the once-weekly 70 mg dose, which is one reason the weekly formulation became standard.

Women frequently describe taking the pill incorrectly: lying down after, drinking only a small sip of water, or taking it with food. Proper administration, meaning a full 8-ounce glass of plain water, staying upright for 30 minutes, and taking it on an empty stomach, cuts GI events substantially. If you stopped because of GI symptoms, it is worth asking whether the administration instructions were followed carefully before concluding the drug does not suit you.

Fear of Rare Complications

Atypical femoral fractures and osteonecrosis of the jaw (ONJ) get disproportionate attention relative to their actual incidence. The American Society for Bone and Mineral Research Task Force estimated the absolute risk of atypical femoral fracture at approximately 3.2 to 50 cases per 100,000 person-years, with risk rising after more than five years of use. ONJ risk in oral bisphosphonate users is estimated at 1 in 10,000 to 1 in 100,000 patient-years, a figure far lower than the risk of hip fracture in an untreated postmenopausal woman with a T-score below negative 2.5.

That context matters. Stopping Fosamax because of ONJ fear when your fracture risk is genuinely high may leave you more vulnerable, not less.

What the FLEX Trial Actually Tells You About Stopping

The best clinical data on what happens when you stop alendronate comes from the FLEX (Fracture Intervention Trial Long-term Extension) trial, which remains the reference standard for drug holiday decisions.

FLEX enrolled 1,099 postmenopausal women who had already taken alendronate for approximately five years in the original Fracture Intervention Trial. Women were then randomized to continue alendronate or switch to placebo for an additional five years. The findings shaped current prescribing practice in two important ways.

First, women who stopped after five years and had a femoral neck T-score above negative 2.5 at the time of stopping did not show a significantly higher clinical fracture rate over the following five years compared with those who continued. Second, women with a femoral neck T-score at or below negative 2.5 at the time of stopping did face a higher risk of clinical vertebral fractures.

That means a drug holiday is evidence-supported for lower-risk women after five years, but not for women whose bone density remains in the osteoporosis range. Your personal FLEX profile matters far more than any general recommendation.

What Happens to Bone Density After Stopping

Bone mineral density (BMD) does decline after stopping alendronate, but it declines slowly. In the FLEX placebo group, BMD at the hip dropped by about 2.4% over five years after discontinuation, compared with a 3.7% gain in those who continued. That slower rate of loss compared to untreated early menopause reflects the fact that bisphosphonates are embedded in bone mineral and continue releasing for years.

This residual effect is why a drug holiday, rather than abrupt permanent discontinuation, is the concept that actually appears in clinical guidelines. The bone bank of incorporated alendronate continues to suppress osteoclast activity even after you stop taking pills.

When the Residual Effect Runs Out

The residual protective effect is not indefinite. Bone turnover markers begin rising within weeks to months of stopping, and BMD loss accelerates again, typically around three to five years after the last dose in most studies. The American Association of Clinical Endocrinologists and American College of Endocrinology 2020 guidelines recommend reassessing fracture risk after three to five years off therapy and restarting if BMD is declining significantly or if a new fracture occurs.

Life-Stage Considerations: This Is Not a One-Size Situation

Alendronate use looks different depending on where you are hormonally. The drug is approved and most studied in postmenopausal women, but it is also used in premenopausal women with glucocorticoid-induced osteoporosis, and sometimes in perimenopausal women with very low bone density and high fracture risk.

Postmenopausal Women

This is the core population for alendronate. Postmenopausal women lose approximately 1 to 3% of bone mass per year in the first five to seven years after menopause, driven by estrogen withdrawal. Alendronate reduces that rate and, in the original FIT (Fracture Intervention Trial), reduced vertebral fracture risk by approximately 47% and hip fracture risk by approximately 51% in women with prior vertebral fractures.

If you stopped Fosamax as a postmenopausal woman and your T-score at stopping was better than negative 2.5, a drug holiday may have been appropriate. If your T-score was still in osteoporosis territory and you had a prior fragility fracture, that stopping decision deserves a second conversation with your prescriber.

Perimenopausal Women

Perimenopausal bone loss is real but less severe than in the first postmenopausal years. Bisphosphonates are less commonly first-line in this group. The Endocrine Society's 2019 guideline on postmenopausal osteoporosis notes that hormone therapy remains an acceptable first-line option for perimenopausal and early postmenopausal women under 60 who also have menopausal symptoms, which may eliminate the need for bisphosphonate therapy in this group entirely.

If you are perimenopausal and were placed on alendronate, it is worth asking whether menopausal hormone therapy (MHT) was discussed as an alternative with comparable bone protection and additional quality-of-life benefits.

Premenopausal Women

Bisphosphonate use in premenopausal women is largely limited to glucocorticoid-induced osteoporosis, malignancy-related bone loss, or osteogenesis imperfecta. The evidence base in this group is thin. For premenopausal women who stopped alendronate and are now questioning that decision, the calculus is different because estrogen is still present and providing some bone protection.

Pregnancy, Lactation, and Contraception: What You Must Know

Alendronate is contraindicated in pregnancy. This is not a soft caution. Bisphosphonates incorporate into bone and are released slowly over years, meaning fetal exposure can occur even from drug taken before conception.

Animal data show bisphosphonates cross the placenta and incorporate into fetal bone, with potential effects on fetal skeletal development. Human data are limited to case series and case reports, most of which involve accidental first-trimester exposure in women who did not know they were pregnant. Outcomes in those cases have generally been reassuring for the infant, but sample sizes are small and long-term follow-up is absent.

The FDA classifies alendronate as Pregnancy Category C (under the old system), meaning animal studies have shown adverse fetal effects and no adequate human trials exist. Under the current Pregnancy and Lactation Labeling Rule (PLLR), the label states the drug should be used during pregnancy only if the potential benefit justifies the potential risk, which in clinical practice means it is not used.

Contraception Requirement

Because alendronate accumulates in bone and may release into the fetal circulation for years after a woman stops taking it, ACOG and reproductive endocrinologists advise that women of reproductive potential who take bisphosphonates use reliable contraception during treatment and discuss family planning explicitly with their prescriber before starting. The risk to a future pregnancy from bone-stored drug is not precisely quantified, which is the reason this conversation needs to happen before starting, not after.

Lactation

Alendronate is not recommended during breastfeeding. Animal studies show transfer into milk. No adequate human lactation data exist. Because bone mineral density naturally declines during breastfeeding and then recovers after weaning, the clinical rationale for bisphosphonate use during lactation is weak for most women.

If you stopped alendronate because you were planning a pregnancy or were breastfeeding, that was medically appropriate. Restarting after you have finished breastfeeding and are not planning another pregnancy is a reasonable next step to discuss.

Restarting Alendronate: What to Expect

Restarting alendronate after a drug holiday or unplanned discontinuation is not the same as starting fresh. The clinical approach should be structured around three questions.

1. What is your current fracture risk? A new DEXA scan and a FRAX score (the WHO fracture risk assessment tool) should anchor the restart decision. The National Osteoporosis Foundation (now Bone Health and Osteoporosis Foundation) recommends considering pharmacotherapy when FRAX 10-year major osteoporotic fracture probability is at or above 20%, or hip fracture probability is at or above 3%.

2. How long was the drug holiday? A short break of one to two years in a lower-risk woman may not have eroded much benefit. A four-to-five-year break in a higher-risk woman likely warrants treating more aggressively, possibly with an anabolic agent (teriparatide, abaloparatide) before returning to an antiresorptive.

3. Why did you stop? If GI side effects drove discontinuation, switching to a different bisphosphonate delivery method, such as intravenous zoledronic acid (Reclast) once yearly, may remove the barrier entirely. Women who stopped due to ONJ or atypical fracture fear should have that risk quantified individually rather than assumed.

What Real Women Report When Restarting

On Drugs.com reviews and Reddit threads, women who restarted alendronate after a gap describe two predominant experiences. One group notices GI side effects again, particularly if they lapsed on the administration technique during the break. A second group reports no issues on restart and expresses relief that their next DEXA showed stabilization or modest improvement within two years.

The honest picture is that alendronate does not produce dramatic, fast, or visible results that you can feel. The benefit is statistical: you are less likely to fracture. That invisibility is part of why adherence is poor and why regret is complicated. Women describe not knowing whether the drug is "working" because there is no symptom it relieves.

Timeline for Seeing Benefit Again After Restart

BMD gains on restarting alendronate are generally seen at 12 months on DEXA, with the most meaningful changes at the lumbar spine (typically 3 to 5% above baseline after two years) and more modest gains at the femoral neck (1 to 2%). Bone turnover markers, such as serum CTX and P1NP, respond faster, often suppressing within three months of restart, and can be used to confirm adherence and response before the next DEXA.

Does Fosamax Work for Everyone?

No, and being honest about that matters. Alendronate produces a meaningful reduction in fracture risk in women with established osteoporosis and in women with osteopenia plus additional risk factors. The absolute risk reduction is smaller in women with osteopenia alone and no prior fracture.

The FIT trial's osteopenia subgroup showed no statistically significant reduction in hip fracture risk in women without a prior vertebral fracture and a femoral neck T-score above negative 2.5. That does not mean the drug does nothing in this group, but it does mean the benefit-to-burden ratio is less clear.

Secondary non-response is also real. A subset of women show continued BMD decline despite adhering to therapy. This may reflect poor absorption (related to GI conditions, calcium supplement timing, or vitamin D deficiency), secondary causes of osteoporosis that were not identified at baseline, or true pharmacological non-response. Women who do not see any stabilization on two consecutive DEXA scans while on alendronate should be evaluated for secondary causes before the drug is blamed.

The Calcium and Vitamin D Factor

Alendronate does not work well without adequate calcium and vitamin D. The Institute of Medicine's dietary reference intakes recommend 1,200 mg of calcium daily for women over 50 and 600 to 800 IU of vitamin D daily, with many osteoporosis specialists targeting serum 25-hydroxyvitamin D levels above 30 ng/mL. Women who were deficient in vitamin D while taking Fosamax may have experienced a blunted response and may do better on restart if vitamin D status is corrected first.

Who This Is Right For, and Who Should Ask More Questions

Alendronate is a reasonable first-line choice if you are a postmenopausal woman with a T-score at or below negative 2.5, or a T-score between negative 1.0 and negative 2.5 with a FRAX 10-year major fracture probability at or above 20%. It is also appropriate for women on long-term glucocorticoids regardless of menopausal status.

Women for whom the calculus is more complex include:

• Women under 45 with low bone density. Secondary causes, including premature ovarian insufficiency, eating disorders, thyroid dysfunction, and celiac disease, should be ruled out before starting. Bisphosphonate use in premenopausal women of childbearing potential requires explicit contraception counseling.
• Women with active or planned pregnancy. Do not restart alendronate until family planning is complete or until you have had a thorough discussion about relative risks with a reproductive endocrinologist or maternal-fetal medicine specialist.
• Women with severe reflux or Barrett esophagus. Intravenous zoledronic acid is a safer option.
• Women with a prior atypical femoral fracture or ONJ. Continuing or restarting oral bisphosphonates in this context requires specialist input.
• Women who have already taken oral bisphosphonates for more than 10 years. The benefit-to-risk ratio shifts. Sequential therapy with a different mechanism, or a structured holiday, may be a better next step.

Making the Conversation With Your Prescriber Productive

Women frequently report leaving osteoporosis appointments without clarity on why they are taking the drug, how long they will take it, or what the stopping plan looks like. Arriving with specific questions changes that dynamic.

Ask for your current T-scores at the femoral neck and lumbar spine, not just a summary. Ask for your FRAX score and what 10-year fracture probability it reflects. Ask how long your prescriber plans to continue therapy and under what conditions a drug holiday would be appropriate. If you stopped without a clear plan, ask whether a bone turnover marker test (CTX or P1NP) would help determine where your bone remodeling stands before committing to restart.

The American College of Obstetricians and Gynecologists recommends that osteoporosis management be individualized and that the decision to continue, pause, or switch therapy be based on serial DEXA results, fracture history, and updated FRAX calculation.

The most common regret women express is not making a wrong decision about stopping or continuing. It is not having enough information at the time to make the decision confidently. A DEXA scan and a 20-minute structured conversation with a prescriber who specializes in bone health can close most of that gap.