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

Most common
abdominal pain (1% to 10%)
dyspepsia (1% to 10%)
acid regurgitation (1% to 10%)
nausea (1% to 10%)

Prolia

Most common
back pain (up to 34.1%)
pain in extremity (up to 11.4%)
musculoskeletal pain (up to 7.4%)
hypercholesterolemia (up to 7.2%)

Fosamax vs. Prolia Dosage

Fosamax

Dosage
Dosage Table
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

Dosage
Dosage Table
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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