Bisphosphonates Print Page

What are bisphosphonates?

  • Bisphosphonates are a group of drugs that help slow bone loss. They help to keep your bones to strong and prevent them from thinning (osteoporosis).
  • Using them long-term can decrease your risk of having a broken hip or a spine fracture.

What is the typical dose?

  • The dose depends on which bisphosphonate you take:
  • Alendronate (Fosamax®)
    • 70mg once WEEKLY in the morning, on an empty stomach with a full glass of plain water.
    • Do not take with other food, medications, calcium or dairy products.
    • Stay upright for 30 minutes after dose.
  • Risedronate (Actonel®)
    • 35mg once WEEKLY, on an empty stomach with a full glass of plain water OR
    • 150mg once MONTHLY on an empty stomach with a full glass of plain water
    • Do not take with other food, medications, calcium or dairy products.
    • Stay upright for 30 minutes after dose.
  • Zoledronic Acid (Aclasta®) – 5mg once YEARLY by injection over 15 minutes
    • Drink at least 2 glasses of water before and after the treatment.

How do bisphosphonates work?

  • In osteoporosis, your body removes more bone than it replaces. Medications, such as corticosteroids/glucocorticoids or “steroids” (eg, prednisone), increase this bone removal. Bisphosphonates help correct this by slowing down the body’s rate of bone removal. Your bone thickness is measured by a test (bone mineral density) and this is one way we check to see if the bisphosphonate is working for you. The other is determining if you’ve had a fracture.

What are the possible side effects of bisphosphonates?


  • Stomach pain, heartburn, nausea, pain in bones, muscles
    • Get better with time.
    • If you have a history of esophagus problems or kidney problems, inform your doctor/pharmacist before starting the medication.
    • Talk to your doctor or pharmacist if it is severe.

Less common:

  • Low calcium levels (numbness, tingling, muscle spasms)
    • Discuss your calcium intake with your doctor, pharmacist, or dietitian. They can help you manage this.


  • Wounds in your jaw from limited blood supply
    • Talk to your dentist before having dental work done.
    • Tell your doctor if you have persistent pain in your mouth or jaw.
  • Unusual break in your thigh bone
    • Talk to your doctor if you have new or unusual pain in your hip or thigh.

Side effects with zoledronic acid infusion

  • Flu like symptoms during and after the dose infusion (fever, fatigue, chills, feeling unwell)

Are there medications I should avoid when taking bisphosphonates?

  • Vitamin and mineral supplements may contain ingredients (such as calcium, magnesium and iron) that can stop your body from absorbing bisphosphonates (when taken orally).  Try to avoid taking these products within 2 hours of taking your bisphosphonate.

What do I do if I miss a dose?

  • For weekly dosing, take 1 tablet on the day you first remember having missed your dose. Then resume your normal schedule on your regular day of the week. Do not take 2 doses on 1 day.
  • For monthly dosing, if the next month’s dose is MORE than 7 days away, take the missed dose on the morning you remember. Then resume your normal schedule. If the next dose is LESS than 6 days away, wait until the next scheduled dose.

How long will I have to be on bisphosphonates?

  • Each patient is different and this is something you should discuss with your doctor or pharmacist. It depends on your risk for having a fracture over the next 10 years. Talk to your doctor or pharmacist before deciding to stop your medication.

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