These drugs are used to treat breast cancer in postmenopausal women. They work by blocking the conversion of androgens into estrogen in the body. Why does this matter for your bones? Because estrogen is one of the greatest protectors of the female bone. It’s what keeps the demolition team, the osteoclasts, in check. When you block estrogen with these medications, it’s like taking the brakes off a car on a steep hill. Bone demolition accelerates, even faster than natural menopause would cause.
But now, pay close attention to what I’m about to say. Do not stop this medicine. This medicine is protecting you from cancer. We can monitor bones, we can replenish them, we can take care of them, but cancer sometimes doesn’t give a second chance. Now you understand why your oncologist told you to take that calcium, why they ordered a bone density scan every year, why they might have prescribed that anti-osteoporosis injection you didn’t understand the purpose of. They already knew. Now you know too. If you take anastrozole or letrozole, your mission is simple: at your next appointment, ask your oncologist, “Doctor, how are my bones? Are we monitoring them properly?”
4. Migraine & Seizure Medications That Block Calcium’s Entry
Here we’re talking about some anticonvulsants. Look in your box for phenytoin, carbamazepine, or phenobarbital. Brand names might include Dilantin, Tegretol, or Gardinal. These are much more common medications than we imagine, often used for seizures, nerve pain, and even migraines.
What do they do to the bone? Something very treacherous. These medications are enzymatic inducers. They speed up the liver’s work so much that the liver starts destroying active vitamin D faster than the body can replace it. And without vitamin D, calcium simply cannot get into the bone. You can consume all the calcium in the world—milk, cheese, supplements—it won’t matter, because without vitamin D, the door to the bone is closed. When the body realizes calcium isn’t reaching the bone, it goes into emergency mode. It activates the parathyroid glands, which send a message: take calcium from the bones and put it in the blood. Your body starts robbing calcium from your bones to keep your blood levels stable. It’s as if your liver is devouring the very vitamin that protects your bones.
Did you find carbamazepine or phenytoin in your box? Now you understand why your neurologist may have ordered a vitamin D test. It wasn’t a random test. They were watching over your bones without you even realizing it. If you’ve been taking one of these medications for more than a year, talk to your neurologist. Ask about your vitamin D levels and whether your supplementation is adequate. And never stop an anticonvulsant on your own. Stopping suddenly can cause a severe seizure.
3. The Thyroid Medication That Can Double the Rate of Bone Loss
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