Fosamax vs. Prolia
See how Fosamax and Prolia compare on approved uses, dosing, side effects, and cost.
Key Takeaways
Fosamax is a bisphosphonate pill taken daily or weekly, while Prolia is an antibody injection given by a healthcare provider every six months.
Fosamax mainly causes GI symptoms like stomach pain and heartburn, while Prolia's most common side effect is back pain, reported in up to a third of users.
Stopping Prolia without starting another bone medication can trigger a rebound rise in spine fractures, a risk Fosamax does not carry.
Fosamax vs. Prolia Drug Summary
Fosamax
Fosamax (alendronate) is an oral bisphosphonate used to treat and prevent osteoporosis and to manage Paget's disease of bone. It slows bone breakdown and is taken as a tablet, either once daily or once weekly, on an empty stomach with plain water.
Prolia
Prolia (denosumab) is a RANKL-inhibiting antibody used to treat osteoporosis in people at high risk of fracture. It is given as a single injection under the skin, administered in a clinic once every six months.
Fosamax vs. Prolia Side Effects
Fosamax
Prolia
Fosamax vs. Prolia Dosage
Fosamax
Prolia
| STAGE | DOSE | WHEN |
| Starting dose | 5 mg once daily | At the start |
| Maximum dose | 40 mg once daily | If needed |
| Dose changes | 4 increases | As tolerated |
| STAGE | DOSE | WHEN |
| Starting dose | 60 mg every 6 months | At the start |
| Maximum dose | 60 mg every 6 months | Same as starting |
| Dose changes | None | Fixed dose |
Fosamax
| STAGE | DOSE | WHEN |
| Starting dose | 5 mg once daily | At the start |
| Maximum dose | 40 mg once daily | If needed |
| Dose changes | 4 increases | As tolerated |
Prolia
| STAGE | DOSE | WHEN |
| Starting dose | 60 mg every 6 months | At the start |
| Maximum dose | 60 mg every 6 months | Same as starting |
| Dose changes | None | Fixed dose |
Fosamax vs. Prolia Indications
Fosamax
Fosamax is FDA-approved for both treating and preventing osteoporosis in postmenopausal women, and for increasing bone mass in men with osteoporosis. It also treats glucocorticoid-induced osteoporosis and Paget's disease of bone.
Treatment of osteoporosis in postmenopausal women
Prevention of osteoporosis in postmenopausal women
Increasing bone mass in men with osteoporosis
Glucocorticoid-induced osteoporosis
Paget's disease of bone
Prolia
Prolia is FDA-approved for postmenopausal women and men with osteoporosis who are at high risk of fracture. It also covers bone loss linked to certain cancer treatments, including aromatase inhibitors and androgen deprivation therapy.
Postmenopausal osteoporosis at high fracture risk
Osteoporosis in men at high fracture risk
Glucocorticoid-induced osteoporosis
Bone loss from androgen deprivation therapy
Bone loss from aromatase inhibitor therapy
Fosamax vs. Prolia Pros and Cons
Fosamax
Fosamax has decades of use, a low-cost generic option, and flexible daily or weekly dosing that patients take on their own. Its main drawbacks are GI irritation and strict administration rules that some patients find hard to follow.
Pros
Low-cost generic available since 2008
Take at home, no clinic visit needed
Long track record of safety data
Cons
Requires staying upright 30+ minutes after dosing
Common GI side effects like heartburn and nausea
Not usable with severe kidney impairment
Roughly $166 to $210 per month without insurance
Prolia
Prolia offers convenience through infrequent dosing but requires a clinic visit and carries a rebound fracture risk if stopped abruptly. It also comes with a boxed warning about severe low calcium in advanced kidney disease.
Pros
Only 2 doses per year, given by a provider
No pill-related GI or esophageal issues
Option for patients who can't tolerate oral bisphosphonates
Cons
Requires a healthcare provider visit each dose
Rebound vertebral fractures if stopped without follow-up
Boxed warning for severe hypocalcemia in kidney disease
Roughly $1,600 to $2,000 per injection, twice a year
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