Osteoporosis is a disease that affects your bones. It means you have bones that are thin and brittle, with lots of holes inside them like a sponge. This makes them easy to break. These fractures can be disabling and make it hard for you to live on your own.

Low bone density means you are at a higher risk for osteoporosis.

Low bone density is sometimes called osteopenia. It's important to know that low bone density is not a disease. It can happen normally with aging. Not everyone with low bone density gets osteoporosis or has a fracture. If you have low bone density, it is one thing that you and your doctor will talk about when you decide whether bisphosphonates are right for you.

Your doctor may suggest a test to find out your bone density, depending on your age and your health.

Whether or not you take medicine, experts recommend that you:^{footnote 2}

• Get enough calcium and vitamin D.
• Get regular weight-bearing exercise.
• Avoid drinking too much alcohol.
• Avoid smoking.

Most of these healthy habits are good for your body for other reasons, too. For example, it's good for your heart if you get regular physical activity, avoid drinking too much, and avoid smoking.

Some women decide with their doctors that they want to try healthy habits alone without taking medicines. Your doctor will probably ask you to check in over time to see how that plan is working. Having your doctor keep track of your risk of a fracture can help you know if healthy habits alone are still enough to protect your bones.

Bisphosphonates are the most common medicines used to prevent bone loss in people who have osteoporosis. They slow the way bone dissolves and is absorbed by your body. They can increase bone thickness and strength.

They include:

• Alendronate (Fosamax).
• Risedronate (Actonel).
• Zoledronic acid (Aclasta).

Different kinds of bisphosphonates are taken in different ways. Many are taken once a week. Others are taken once a day or once a month.

Most of these medicines should be taken in the morning with a full glass of water at least 30 minutes before eating a meal, drinking a beverage, or taking any other medicine.

Zoledronic acid is injected into a vein in your arm. Most people who use it get just one dose each year.

Some women may benefit more from taking bisphosphonates than other women can. It's important to find out your risk of having a fracture.

• The higher your risk of a fracture, the more likely it is that bisphosphonates can help prevent a fracture.
• The lower your risk of a fracture, the less likely it is that taking these medicines can help prevent a fracture.

Your doctor can help you understand your risk of having a fracture. Your risk depends on several things, including:

• Your age, height, and weight.
• If you've had a fracture in the past.
• If one of your parents ever fractured a hip.
• If you smoke.
• How much alcohol you drink.
• The results of a bone density test, if you've had one.

Your doctor might use the FRAX tool to help predict your risk of having a fracture related to osteoporosis in the next 10 years. You can use this tool too. Go to the website at www.sheffield.ac.uk/FRAX, and click on Calculation Tool. If you have had a bone density test on your hip, you can enter your score. If you haven't had that test, you can leave the score blank.

For women who have been through menopause:

• If you have osteoporosis (your T-score is -2.5 or less) or you havehad a fracture, taking bisphosphonates lowers your risk of having a fracture. This includes lowering your risk of a hip fracture, which is a more harmful kind of fracture that can happen with osteoporosis.^{footnote 3}
• If you haven't had a fracture and you have low bone density (your T-score is between -1.0 and -2.5, sometimes called osteopenia), taking bisphosphonates might lower your risk of having a fracture. This evidence is not as strong. Experts recommend that you and your doctor think about not only your bone density but also those other things about you that affect your risk of having a fracture. That will tell you how likely it is that taking bisphosphonates might prevent a fracture.^{footnote 4footnote 2footnote 3footnote 1}

Side effects can happen while taking bisphosphonate pills. For example, some women feel heartburn or irritation of the esophagus.^{footnote 3} These side effects can usually be avoided by following the instructions for taking your medicine.

If you start taking bisphosphonates and have problems with side effects, you can try other medicines. Talk with your doctor.

Bone side effects

Certain bone problems have been reported in women taking bisphosphonates. These side effects seem to be more likely if you take these medicines for more than 5 years.^{footnote 2footnote 5footnote 6}

Out of 1,000 people, about 1 person has a bone side effect during a year of taking bisphosphonates. That means 999 out of 1,000 people do not have a bone side effect.^{footnote 3footnote 5footnote 7}

There are two types of bone side effects:

• Problems with the jaw bone. This is called osteonecrosis. Research has shown that bisphosphonates seem to increase the chance of this jaw problem. If it happens, surgery may be needed.^{footnote 3}
• A certain kind of fracture of the thigh bone. This is called an atypical fracture. More research is needed to find out if taking bisphosphonates is a cause of these fractures.^{footnote 3footnote 6}

Doctors don't know for sure how long people need to take bisphosphonates. That's because there hasn't been enough research to show how helpful these medicines are if you take them for more than 5 years. And the bone side effects of bisphosphonates seem to be more likely in people who take the medicines for more than 5 years.^{footnote 2footnote 3}

If you decide to take bisphosphonates, you and your doctor can talk over time about how long to take them, based on your fracture risk and other factors.

Bisphosphonates aren't right for everyone. Depending on your health, your doctor may suggest other medicines to help prevent bone loss. Or your doctor may suggest these other medicines if you are having a problem with side effects from bisphosphonates.

Other medicines include:

• Calcitonin (Calcimar).
• Denosumab (Prolia).
• Hormone therapy (HT) or estrogen therapy (ET).
• Raloxifene (Evista).
• Teriparatide (Forteo).