Romosozumab (Evenity) — The "Dual-Action" Bone Builder

• How romosozumab works differently from other bone medications
• What the 12-month treatment course looks like
• Who benefits most — and who should not take this medication
• Important cardiovascular safety information
• Why you must follow romosozumab with another bone medication

Your body produces a protein called sclerostin that acts like a brake on bone formation. When sclerostin levels are high, your bone-building cells (osteoblasts) slow down. Romosozumab works by blocking sclerostin — releasing the brake so your bones can build themselves up again.

But romosozumab does not stop there. By blocking sclerostin, it also reduces bone breakdown at the same time. This dual action — building new bone while protecting existing bone — is what makes romosozumab unique among all osteoporosis medications.

Think of it this way: most bone medications either hire more builders (anabolic agents) or slow down the demolition crew (antiresorptive agents). Romosozumab does both at once — like bringing in an extra construction crew while also telling the demolition crew to take a break.

Romosozumab is the only osteoporosis medication that simultaneously builds new bone and slows bone loss. This dual action produces the fastest bone density gains of any available treatment.

Romosozumab is given as a subcutaneous injection (under the skin) once a month for 12 months. Each monthly dose consists of two injections (one in each arm or one in each thigh), given at your doctor's office.

What to expect:

• Monthly visits to your doctor's office for 12 months
• Two injections per visit (the full dose is split into two injections because of the volume)
• Each injection takes just a few seconds
• Most people experience only mild discomfort at the injection site
• The full treatment course is exactly 12 months — no more, no less

Results you can expect

Clinical trials have shown remarkable results with romosozumab:

• Spine bone density increased by approximately 13% in 12 months
• Hip bone density increased by approximately 7% in 12 months
• Vertebral fracture risk was reduced by 73% compared to placebo in the first year (FRAME trial)

These are among the largest bone density gains ever seen with any osteoporosis medication.

Romosozumab is typically recommended for people at very high risk of fracture:

• Those who have already had a fracture due to osteoporosis
• Those with very low bone density (very low T-scores)
• Those who have had fractures despite being on other osteoporosis treatments
• Those at imminent fracture risk (recent fracture within the past 2 years)

Your doctor may consider romosozumab as a first-line treatment for very high-risk patients, in line with guidelines from the AACE, NOF, and Endocrine Society that recommend starting with an anabolic agent for the highest-risk individuals.

Romosozumab comes with an important safety consideration that you and your doctor must discuss:

In one clinical trial (the ARCH trial), there was a slightly higher rate of cardiovascular events (heart attack, stroke) in patients taking romosozumab compared to those taking alendronate during the first year.

Because of this finding:

• The FDA has placed a boxed warning (the most prominent type of warning) on romosozumab regarding cardiovascular risk
• Romosozumab should not be used in patients who have had a heart attack or stroke within the past year
• Your doctor will carefully evaluate your cardiovascular risk before prescribing romosozumab
• If you have risk factors for heart disease (high blood pressure, high cholesterol, diabetes, smoking), your doctor will weigh these against the benefits of treatment

Important context: The absolute increase in cardiovascular events was small, and the other major trial (FRAME) did not show the same signal. Nevertheless, this warning must be taken seriously.

If your doctor recommends romosozumab, they have carefully considered your heart health and determined that the benefits of rapid bone strengthening outweigh the cardiovascular risks for your specific situation. Do not hesitate to ask questions about this.

Romosozumab's bone-building effect is strongest during the 12-month treatment course. After that, the effect diminishes. If you do not follow romosozumab with another medication, the bone density gains will gradually be lost.

This is why sequential therapy is essential:

After completing your 12-month course of romosozumab, your doctor will transition you to a bone-protecting medication — typically:

• Denosumab (injection every 6 months), or
• A bisphosphonate (such as alendronate or zoledronic acid)

This follow-up medication "locks in" the bone density you gained during romosozumab treatment. Think of it as applying a protective coating to the newly reinforced structure of your house.

The ARCH trial showed that patients who received romosozumab for 12 months followed by alendronate had significantly fewer fractures over the following years compared to patients who received alendronate alone.

• Injection site reactions — pain, redness, or swelling where the injection was given (usually mild and short-lived)
• Joint pain — some patients experience mild joint aches
• Headache — usually temporary
• Low calcium — your doctor will ensure your calcium and vitamin D levels are adequate

Rare side effects

As with other bone medications, romosozumab has been associated with very rare cases of:

• Osteonecrosis of the jaw (ONJ)
• Atypical femur fractures (AFF)

These are extremely rare during a 12-month course. See our article on rare side effects for more information.

• Ask your doctor whether romosozumab might be appropriate for your level of fracture risk
• Share your complete heart health history — including any history of heart attack, stroke, or cardiovascular risk factors
• If you are starting romosozumab, schedule all 12 monthly appointments in advance so you do not miss any
• Take calcium and vitamin D as recommended — they support the bone-building process
• Plan ahead for what comes after — ask your doctor about the follow-up medication you will take after your 12-month course
• Have a dental checkup before starting treatment

Q: Is romosozumab better than other osteoporosis medications? A: Romosozumab produces the fastest bone density gains, but it is not right for everyone. It is typically reserved for people at very high fracture risk and requires careful cardiovascular screening. For many people, other medications are equally appropriate and effective.

Q: Why can I only take romosozumab for 12 months? A: The bone-building effect of romosozumab peaks during the first 12 months and then diminishes as the body adapts. Continuing beyond 12 months does not provide additional benefit. The strategy is to build bone rapidly with romosozumab, then switch to a maintenance medication.

Q: I had a heart attack three years ago. Can I take romosozumab? A: Possibly, but this requires careful evaluation by your doctor. The boxed warning specifically cautions against use in patients who have had a cardiovascular event within the past year. If your event was more distant and your cardiovascular health is stable, your doctor may consider it — but this is a decision that requires individual assessment.

Q: What if I miss a monthly injection? A: Contact your doctor to reschedule as soon as possible. Unlike denosumab, missing a single romosozumab dose does not cause rebound bone loss, but staying on schedule ensures the best results from your 12-month course.

Q: Are the two injections per visit painful? A: Most patients report only mild discomfort — a brief pinch or slight stinging at the injection sites. The injections are given under the skin with fine needles. Let your healthcare team know if you are anxious about injections; they can help.

• Cosman F, et al. Romosozumab Treatment in Postmenopausal Women with Osteoporosis (FRAME trial). N Engl J Med. 2016;375(16):1532-1543.
• Saag KG, et al. Romosozumab or Alendronate for Fracture Prevention in Women with Osteoporosis (ARCH trial). N Engl J Med. 2017;377(15):1417-1427.
• National Osteoporosis Foundation (NOF). Clinician's Guide to Prevention and Treatment of Osteoporosis. 2021.
• Camacho PM, et al. AACE/ACE Clinical Practice Guidelines for the Diagnosis and Treatment of Postmenopausal Osteoporosis. Endocr Pract. 2020;26(Suppl 1):1-46.
• FDA Prescribing Information for Evenity (romosozumab-aqqg). Revised 2023.

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