Causes of osteoporosis and broken bones

Osteoporosis and broken bones have a number of known risk factors, which cause bones to lose strength. Some do this by reducing how much bone tissue your body makes and repairs, known as bone density. Others influence how strong your bone tissue is.

Understanding your risk factors for osteoporosis and broken bones can help you identify if there's anything you can change. Remember, it's never too late to start taking action for your bones - even after a diagnosis.

Your doctor often uses your risk factors to build up a picture of your overall bone health, and risk of breaking a bone. They do this using a fracture risk assessment test. The results of this test help your doctor decide if you need an osteoporosis medication.

Learn more in our video, What is osteoporosis?

Risk factors you can change

Low body weight

If you have low body weight, you're more likely to have less bone tissue.

If you're older, having low body weight also means you have less fat padding around the hips, to cushion the impact of a fall. This makes broken bones more likely if you trip and fall.


Smoking slows down the cells that build bone in your body.

If you're a woman, smoking also increases your chances of an earlier menopause. Postmenopausal women have an increased risk of osteoporosis and breaking a bone.

Drinking too much alcohol

Alcohol affects the cells that build and break down bone.

It also makes you unsteady on your feet, making you more likely to trip, fall and break a bone.

Slips, trips and falls

If you have low balance, coordination and reflexes, you are more likely to trip or stumble, and potentially break a bone in a fall.

Risk factors you can't change

Your genes

Your genes determine the potential size and strength of your skeleton. Research shows that if one of your parents broke their hip, you are more likely to break a bone yourself.


From your late thirties, the amount of bone tissue you have starts to naturally decrease. This happens at different rates in different people. The amount of bone tissue you have is known as your bone density, which is measured in a bone density scan.

As you get older, your bone tissue loses strength and becomes more likely to break in general, regardless of your bone density.

Becoming less steady on your feet also becomes more likely with age. This increases your risk of slipping or tripping, and breaking a bone in a fall.

Being a woman

Osteoporosis and broken bones are more common in women than men.

Your bones lose strength at a faster rate after the menopause. This is because levels of oestrogen (the female sex hormone that helps keep bones strong) decrease.

Women tend to live longer, on average, so are more likely to live with the lower bone strength that comes with age.

Women tend to have smaller bones than men. Having bigger bones is found to reduce the risk of broken bones.

A history of broken bones

If you've broken bones easily in the past, including in the spine, you are much more likely to break a bone in the future. Research shows that after one broken bone you are two to three times more likely to have another.

Medications that increase risk

If you are taking one of these medications, talk to your doctor. They can suggest ways to limit the effects on your bones. Don’t make any changes without talking to your doctor first. You may do yourself more harm than good.

Known to affect bone strength

May affect bone strength, but more research is needed

  • medications to reduce inflammation of the stomach and oesophagus (proton pump inhibitors (PPIs))
  • diabetic medications in the glitazone group, including pioglitazone
  • injectable progestogen contraceptives, such as Depo Provera
  • some medicines used for mental health conditions, such as:
    • tricyclic antidepressants
    • selective serotonin reuptake inhibitors (SSRIs)

Medical conditions that increase risk

If you have one of these medical conditions, talk to your doctor. Proper care of these conditions often reduces their effect on your bone health.

Known to affect bone strength

  • rheumatoid arthritis
  • low levels of the sex hormone oestrogen in women, as a result of:
    • early menopause
    • having a hysterectomy with removal of ovaries, before the age of 45
    • anorexia nervosa
    • Turner’s syndrome
    • excessive exercise
  • low levels of the sex hormone testosterone in men, as a result of:
    • surgery for some cancers
    • Klinefelter syndrome
    • Kallman syndrome
    • naturally lower testosterone levels
  • hyperthyroidism, in which levels of thyroid hormone are abnormally high
  • parathyroid disease, in which levels of parathyroid hormone are abnormally high
  • conditions that affect the absorption of food, such as:
  • conditions that cause long periods of immobility, such as stroke

May affect bone strength, but more research is needed

  • diabetes
  • HIV (AIDS)
  • liver disease
  • cystic fibrosis
  • dementia
  • Parkinson’s disease

Organ transplant recipients and people with some respiratory diseases may also be at more risk, although more research is needed to understand why.

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