Calcitonin Side Effects: What You Need to Know Before Using It

When you hear calcitonin, a hormone used to lower blood calcium and treat bone conditions like osteoporosis and Paget’s disease. Also known as salmon calcitonin, it’s often prescribed when other treatments aren’t suitable — but it’s not without risks. Many people assume it’s safe because it’s a naturally occurring hormone, but synthetic versions can trigger reactions you might not expect.

Common side effects of calcitonin include nausea, flushing, and a metallic taste in the mouth — especially after the first few injections. Some users report dizziness or headaches, and skin redness at the injection site isn’t rare. Less common but serious risks include allergic reactions, low calcium levels (which can cause muscle cramps or tingling), and, in rare cases, an increased risk of certain cancers with long-term use. The FDA flagged this in 2012 after reviewing data from over 10,000 patients, and since then, many doctors have moved away from calcitonin unless absolutely necessary.

It’s not just about the drug itself — calcitonin for osteoporosis is often chosen when patients can’t take bisphosphonates or denosumab due to kidney issues or GI intolerance. But if you’re on other meds — like diuretics or thyroid drugs — interactions can happen. Even something as simple as taking calcium supplements at the same time can mess with how calcitonin works. And if you’re older or have kidney problems, your body clears it slower, which increases side effect chances.

There’s also the question of how long you take it. Calcitonin isn’t meant for lifelong use. Most treatment courses last 6 to 12 months, and doctors usually check bone density and blood calcium levels before and after. If you’re using it for bone pain from metastatic cancer, the goal is symptom relief, not long-term bone building. That’s a key difference from other osteoporosis drugs.

What you won’t find in the brochure is how many people just stop taking it. The side effects are annoying enough that compliance drops fast. One study showed nearly 40% of patients quit within three months — not because it didn’t work, but because they couldn’t tolerate the nausea or the daily shots.

So if you’re considering calcitonin, ask your doctor: Is this really the best option for me? Are there safer, more effective alternatives? What are the real odds of side effects based on my age and health? Don’t just accept it because it’s been around for decades. The landscape has changed.

Below, you’ll find real comparisons, patient experiences, and updated guidance on calcitonin and its alternatives — from what works today to what’s being phased out. No fluff. Just what matters for your health.