At a glance

What is calcitonin-salmon?

Calcitonin-salmon is a lab-made copy of calcitonin, a hormone that helps regulate how much calcium is in the blood and how bone is maintained. The version used in medicine is modeled on the calcitonin found in salmon rather than the human form because the salmon hormone is more potent and longer-lasting in the body. It is approved by the FDA¹ and has been used in clinical practice for decades under the brand names Miacalcin and Fortical.

How does it work?

It works by putting a brake on the cells that break down bone. Bone is constantly being remodeled: cells called osteoclasts dissolve old bone while others build new bone. Calcitonin-salmon binds to calcitonin receptors² on osteoclasts and quiets their activity, which slows the release of calcium from bone into the blood. It also nudges the kidneys to pass more calcium in the urine. Together these effects lower blood calcium and can modestly protect bone.

What is it used for?

Calcitonin-salmon is approved for three main situations:

• In postmenopausal osteoporosis, it is used to help reduce the risk of spinal fractures in women who are more than five years past menopause and who cannot use other treatments.
• In Paget's disease of bone, a disorder in which bone is remodeled too quickly and becomes weak or misshapen, it helps bring that overactive turnover back toward normal.
• In hypercalcemia, a dangerous rise in blood calcium, the injection can be used for its rapid calcium-lowering effect.

How is calcitonin-salmon taken?

There are two main ways to use calcitonin-salmon, and the right one depends on the condition.

The nasal spray is the more convenient, needle-free option and is used for postmenopausal osteoporosis. It is delivered as a single spray into one nostril each day, alternating nostrils from day to day. Because it avoids injections, many people find it easier to stay on long term.

The injection is given either under the skin (subcutaneously) or into a muscle (intramuscularly). This form is used for Paget's disease and for hypercalcemia, and it can also be used for osteoporosis when the spray is not suitable. For hypercalcemia in particular, the injection is preferred because it lowers blood calcium quickly. People who need the injection long term are sometimes taught to give it to themselves at home, similar to how insulin is self-administered.

What does the research say?

The strongest evidence comes from a large trial of the nasal spray in osteoporosis. According to PubMed, the five-year PROOF study³ of 1,255 postmenopausal women found that the 200 IU daily nasal dose reduced the risk of new spinal fractures by about 33% compared with placebo. The result was statistically significant, but the effect was modest and, notably, the higher and lower doses tested did not show the same clear benefit, which left some uncertainty about how robust the finding was.

Safety and the cancer-risk review

The most important safety development came years after approval. In 2013, a reassessment⁴ by European regulators, echoed by an FDA advisory committee, pooled data across trials and found a small but consistent increase in cancer rates among people treated with calcitonin over long periods. Regulators concluded that the modest benefit no longer clearly outweighed this risk for routine, long-term osteoporosis use.

As a result, the nasal spray's role in osteoporosis was narrowed, and calcitonin-salmon is now generally reserved for people who cannot take other, better-established bone treatments. More common, milder side effects include nasal irritation with the spray and nausea or flushing with the injection. The injection's label also warns of serious allergic reactions and low blood calcium.

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