The short answer
Bisphosphonates and denosumab are bone-modifying drugs used to strengthen bone and reduce fractures when cancer affects bone. Both carry a small but real risk of a jaw condition called osteonecrosis, which is why a dental checkup before starting, and good oral hygiene throughout, matters.
Bone-modifying drugs, including bisphosphonates like zoledronic acid and denosumab, are used to strengthen bone and lower fracture risk when cancer affects bone .
These drugs work differently in the body but both reduce the activity of cells that break down bone, called osteoclasts.
Osteonecrosis of the jaw, a rare but serious condition where jaw bone tissue is damaged, is a known risk with both bisphosphonates and denosumab, especially with longer use.
A dental checkup and any needed dental work before starting these drugs, plus good ongoing oral hygiene, are the main ways to lower this risk.
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This page is for people who take, or may start, bone-modifying drugs such as zoledronic acid or denosumab. It explains why they are used, the rare jaw risk, and which warning signs to report.
Why bone-modifying drugs are used
Sometimes cancer spreads to bone. Sometimes cancer treatment weakens bone as a side effect. In either case, doctors often recommend bone-modifying drugs. These drugs lower fracture risk and strengthen bone.
There are two main types: bisphosphonates, such as zoledronic acid, and denosumab, given by injection. Both work by slowing down osteoclasts. Osteoclasts are cells that normally break down old bone as part of the body's ongoing bone renewal process. Slowing them helps bone stay stronger when cancer or treatment side effects are wearing it down faster than usual.
Doctors commonly use these drugs for bone metastases (cancer that has spread to bone) from several cancer types.
The main risk to know about: osteonecrosis of the jaw
Osteonecrosis of the jaw, often shortened to ONJ, is a rare but serious condition. A section of jaw bone loses its blood supply and fails to heal properly. Sometimes it becomes exposed.
Both bisphosphonates and denosumab carry this risk. Research has helped define how the risk builds over time. A large NCI-funded study followed nearly 3,500 people with cancer in their bones who were planning to take zoledronic acid. It found the risk was about 1% after one year of treatment, 2% after two years, and 3% after three years.
Risk varies by cancer type. In the study, the highest rate was in multiple myeloma (4.3%) and the lowest in metastatic breast cancer (2.4%). Risk also varies by how often the drug is dosed. Current smokers were about twice as likely to develop the condition.
Researchers initially hoped denosumab might avoid this risk. NCI reports that later studies found it develops with denosumab at rates comparable to zoledronic acid.
Why dental care before starting matters
Poor dental health raises your risk of developing osteonecrosis of the jaw once you are on one of these medicines. This includes missing teeth, dentures that do not fit well, gum disease, or an upcoming need for dental surgery.
The Xgeva label says an oral examination and preventive dentistry should come before starting, with good oral hygiene during treatment. Your team may suggest:
- A dental checkup before starting treatment, if possible.
- Completing any needed dental work first.
- Keeping up good oral hygiene throughout treatment.
The NCI-reported study found smoking was a risk factor for the jaw condition.
Do not stop your bone-modifying drug on your own before dental care. Ask your care team whether any change is needed. The Xgeva (denosumab) label advises avoiding invasive dental procedures during treatment, and it calls for a dental exam and preventive dental care before you start.
Do not stop or change these medicines on your own. The Xgeva label says to inform the dentist about the medicine before dental procedures, to avoid invasive dental procedures during treatment, and that a temporary pause can be considered if one must be done. The label also says there are no data on the best length of a pause. Tell your cancer team and your dentist before any dental surgery, extraction or implant procedure, so they can plan together.
When to get help sooner
- Call 911 or go to an emergency department if you have a seizure, or muscle spasms and cramping that you cannot control. Severe hypocalcemia, meaning very low blood calcium, is a known risk of denosumab. The Xgeva label says it can be severe, and fatal cases have been reported. Do not drive yourself.
- Call your care team the same day if you notice tingling or numbness around your mouth, in your fingers, or in your toes, or your heartbeat feels like it is skipping. Those are the earlier signals of falling calcium, and the Xgeva label tells patients to seek prompt medical attention for any signs or symptoms of low calcium.
- Call your care team or your dentist within a day or two if jaw or mouth pain will not settle, a tooth socket heals slowly after dental surgery, a tooth works loose, or you can see or feel bare bone in your mouth.
Sources
Common questions
What are bone-modifying drugs used for in cancer care?
They're used to strengthen bone and reduce the risk of fractures mainly when cancer has spread to bone. Ask your care team whether they apply to other bone problems. Bisphosphonates, such as zoledronic acid, and denosumab are the main drugs in this category.
How do bisphosphonates and denosumab work?
Both reduce the activity of osteoclasts, cells that normally break down old bone as part of the body's natural bone renewal process. By slowing this breakdown, these drugs help bone stay stronger, which is especially useful when cancer or treatment side effects are weakening bone faster than normal.
What is osteonecrosis of the jaw?
It's a rare but serious condition where an area of jaw bone loses its blood supply and doesn't heal properly, sometimes becoming exposed. It's a known risk with both bisphosphonates and denosumab, particularly with more frequent, longer-term use in cancer treatment, and after certain dental procedures like extractions. An NCI-reported study of nearly 3,500 people with cancer in their bones who took zoledronic acid found the risk was about 1% after a year of treatment, rising with more years of use, and that it varied somewhat by cancer type.
Why does dental care matter before starting these drugs?
Poor dental health, including missing teeth, dentures, or the need for dental surgery, raises the risk of osteonecrosis of the jaw once you're on these medicines. Getting a dental checkup and completing any needed dental work before starting treatment — and maintaining good oral hygiene throughout — is the main recommended way to lower this risk. Smoking also increases risk, so quitting or cutting back matters here too.
Do I need to stop these drugs for a dental cleaning or other dental care?
Do not stop these medicines on your own for dental care; ask your care team first. The Xgeva label says to avoid invasive dental procedures during treatment. What matters most is telling your dentist you're taking a bisphosphonate or denosumab before any dental surgery or extraction, so they can plan appropriately, and keeping up with good oral hygiene and regular checkups throughout treatment.
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Last updated: 2026-10-02Next planned review: 2027-02-03
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Cancer Explained does not originate medical claims. Every page restates guidance already published by the National Cancer Institute, the CDC, the USPSTF and the FDA, in plain language, with the source cited so you can check the original yourself. AI does the translating and organizing; automated checks test claims, citations, clarity and safety before anything publishes, and this is translation and navigation, not clinical judgment. Nothing here is personal medical advice, and no page can account for your particular situation.
Editorial status: Source checked — This page was written with AI assistance and then compared with the sources listed on it, looking for statements those sources do not back up. That check is not a sentence-by-sentence record and can miss errors. It is not a medical review, and it does not confirm the page is complete or right for your situation.
Human medical review: not completed. Pages here are not signed off by a clinician before they publish. That is not an oversight we are quietly working around: we restate published guidance and cite it, so the authority belongs to the source rather than to us, and every page names where its claims come from — you can verify us instead of trusting us. Where a volunteer clinician has reviewed a page, their name and credentials appear on it; where no name appears, no clinician has checked it. We are glad to have reviewers and are recruiting them, and we do not hold pages back waiting for one. Use this site to understand your situation and to ask better questions of the people treating you.
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