Xgeva Side Effects: Common, Severe, and Long-Term

Xgeva (denosumab 120 mg) causes side effects in the vast majority of patients who take it, with roughly nine out of ten people in clinical trials experiencing at least one treatment-emergent adverse event during therapy. The most frequently reported problems include low blood cell counts, anemia, and drops in calcium and phosphate levels, though the drug also carries rarer but more serious risks like jaw bone damage and unusual fractures. Because Xgeva is prescribed to people already dealing with cancer and bone metastases, separating the drug’s own effects from the disease and concurrent chemotherapy is one of the persistent challenges in understanding its safety profile.

How Xgeva Works and Why Side Effects Follow

Xgeva is a monoclonal antibody that blocks a protein called RANKL, which normally signals the body to build and activate the cells that break down bone. By shutting down that signal, Xgeva slows bone destruction, which is why it is used to prevent fractures and other skeletal complications in cancer patients whose tumors have spread to bone. The same mechanism, though, disrupts normal bone turnover and calcium regulation, and RANKL also plays roles in the immune system. Many of Xgeva’s side effects trace directly back to these biological consequences of blocking a single protein that the body uses for more than one purpose.

The Most Common Side Effects

In a large randomized trial comparing Xgeva with a biosimilar in patients with bone metastases from solid tumors, around 91% of patients in the Xgeva group experienced at least one treatment-emergent adverse event. The most frequent issues, each affecting roughly a fifth to a third of patients, were decreased white blood cell count (about 35%), decreased neutrophil count (about 34%), anemia (about 29%), and hypocalcemia (about 18%). Grade 3 or higher events, meaning those severe enough to potentially require hospitalization, occurred in about 38% of patients, with low neutrophil counts and low white blood cell counts leading that list.

It is worth noting that many of those common events, especially the drops in blood counts, overlap heavily with effects of chemotherapy that most of these patients are receiving at the same time. The treatment-related adverse events more clearly tied to Xgeva itself were hypocalcemia, reported in about 18% of patients, and low phosphate levels (hypophosphatemia), reported in about 14%.

In the adjuvant breast cancer setting, where Xgeva’s parent molecule denosumab was used at a lower dose to prevent fractures in early-stage patients, the side-effect picture looked considerably milder. A large placebo-controlled trial found no meaningful difference in adverse event rates between the drug and placebo groups, with joint pain and symptoms related to aromatase inhibitor therapy being the main complaints in both arms.

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Hypocalcemia and Why It Matters

The side effect most directly linked to Xgeva’s mechanism of action is hypocalcemia, a drop in blood calcium levels. When Xgeva blocks bone resorption, less calcium gets released from bone into the bloodstream. For a healthy person with functioning kidneys and adequate vitamin D, the body compensates. For someone with cancer, kidney problems, poor nutrition, or vitamin D deficiency, the compensation can fall short. Mild hypocalcemia may cause tingling in the fingers or around the mouth. Severe cases can lead to muscle spasms, seizures, or dangerous heart rhythm changes.

Case reports have documented severe hypocalcemia even in patients without the classic risk factors like kidney disease or known vitamin D deficiency, underscoring that the risk is not limited to obviously vulnerable patients.

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Compared with zoledronic acid, the intravenous bisphosphonate that Xgeva often replaces, the risk of hypocalcemia is considerably higher with Xgeva. A meta-analysis of randomized controlled trials found roughly 78% greater incidence of hypocalcemia in patients receiving denosumab versus zoledronic acid.

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Patients on dialysis face an especially high risk because their kidneys cannot help regulate calcium and activate vitamin D the way healthy kidneys do. Guidelines consistently recommend that calcium and vitamin D levels be checked and corrected before starting Xgeva, and monitored throughout treatment.

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Osteonecrosis of the Jaw

Medication-related osteonecrosis of the jaw (MRONJ) is perhaps the most feared side effect of Xgeva, even though it affects a relatively small fraction of patients. The condition involves exposed, dying bone in the mouth that fails to heal, and it can cause pain, infection, difficulty eating, and sometimes disfigurement. In an integrated analysis of three large phase III trials including over 5,700 cancer patients, about 1.8% of those receiving denosumab developed osteonecrosis of the jaw, compared with about 1.3% on zoledronic acid. The difference was not statistically significant, and over 95% of cases were managed conservatively rather than with major surgery.

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A more recent retrospective study of nearly 1,300 patients receiving Xgeva at its standard oncology dose found an incidence rate of about 2.7%. Patients who developed the condition tended to be older (average age around 68) and had received more injections on average than those who did not. The number of Xgeva injections was significantly associated with risk, which makes sense given that longer exposure means more sustained suppression of bone turnover in the jaw.

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Tooth extraction is a major trigger. In the integrated trial analysis, about 62% of patients who developed jaw osteonecrosis had undergone a tooth extraction. This is why oncologists and dental specialists emphasize getting a thorough dental exam and completing any necessary dental work before starting Xgeva. Good oral hygiene and regular dental check-ups throughout treatment are considered essential preventive measures.

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The lower-dose denosumab used for osteoporosis (sold as Prolia) carries a much lower rate of jaw osteonecrosis. The adjuvant breast cancer trial mentioned earlier, which used a dose between the osteoporosis and full oncology doses, found zero cases of jaw osteonecrosis even after proactive adjudication by an expert panel.

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Atypical Femoral Fractures

Atypical femoral fractures are stress fractures in the thigh bone that occur with minimal or no trauma, typically in the shaft of the femur rather than the hip. They are a recognized complication of all drugs that strongly suppress bone turnover, and Xgeva is no exception. In a retrospective review of 253 cancer patients with bone metastases receiving denosumab for a median of about 27 months, one patient developed a confirmed atypical femoral fracture. That translates to an incidence rate of roughly 171 per 100,000 patient-years of follow-up.

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While this rate is low in absolute terms, it is higher than the background rate of atypical femoral fractures in the general population. Patients and providers should be aware that new or unusual thigh or groin pain during Xgeva treatment could signal an incomplete fracture that warrants imaging before it becomes a complete break.

What Happens When You Stop Xgeva

One of the less intuitive risks of Xgeva involves stopping it. Unlike bisphosphonates, which incorporate into bone and continue working for months or years after the last dose, denosumab’s effects wear off within about six months of discontinuation. When they do, bone resorption doesn’t just return to baseline; it can rebound above baseline, sometimes dramatically. This rebound can cause a rapid loss of bone mineral density, and in some patients, it triggers spontaneous vertebral fractures, meaning the spine fractures without any fall or injury.

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The rebound can also cause a surge in blood calcium levels. Reports of rebound hypercalcemia have been most severe in children receiving oncology doses and in adults with underlying conditions affecting calcium metabolism, such as primary hyperparathyroidism. In one reported case, a woman with hyperparathyroidism developed both severe hypercalcemia and spontaneous vertebral fractures after stopping denosumab.

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For cancer patients, the practical implication is that stopping Xgeva should not be done casually. If the drug needs to be discontinued, many clinicians transition patients to a bisphosphonate to blunt the rebound. For patients with advanced disease who stop treatment because of declining health, the rebound is often overshadowed by other medical priorities, but it is still something clinicians factor into decision-making.

How Xgeva Compares with Zoledronic Acid

Since zoledronic acid is the other standard option for preventing skeletal events in cancer patients with bone metastases, the comparative safety profile matters for treatment decisions. A systematic review and meta-analysis of randomized trials found a tradeoff. Xgeva had a lower incidence of kidney toxicity and fewer acute-phase reactions, which are the flu-like symptoms that often follow the first zoledronic acid infusion. But Xgeva was associated with higher rates of both hypocalcemia and jaw osteonecrosis.

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This means the choice between the two often depends on a patient’s individual risk factors. Someone with impaired kidney function may be better served by Xgeva, since zoledronic acid is nephrotoxic and requires dose adjustments or avoidance in patients with poor renal function. Conversely, someone at elevated risk for jaw problems due to poor dental health or planned dental procedures might fare better with zoledronic acid, or at least needs careful dental management before starting Xgeva.

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Infection Risk and Immune Effects

Because RANKL has roles in the immune system beyond bone metabolism, there has been longstanding interest in whether blocking it might impair immunity. A nationwide population-based study in patients with osteoporosis found that denosumab use was significantly associated with a higher risk of several infections, including tuberculosis, candidiasis (yeast infections), herpes zoster (shingles), and fungal infections. The elevated risk appeared most prominent during the first two years of treatment, and the researchers attributed it to the immunosuppressive effects of RANKL inhibition.

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This study was conducted in osteoporosis patients using the lower denosumab dose (Prolia), so the infection risk with the higher oncology dose used in Xgeva is plausibly at least as high, though formal comparative data at the Xgeva dose level are limited. Cancer patients are already immunocompromised from their disease and treatments, which makes disentangling Xgeva’s immune effects from everything else going on particularly difficult in clinical practice.

Skin Reactions

Skin-related side effects from Xgeva are uncommon but recognized. Earlier descriptions of denosumab-associated adverse events included eczema and cellulitis.

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More recently, case reports have documented distinct cutaneous hypersensitivity reactions, including a lichenoid drug eruption with an unusual inflammatory pattern under the microscope. These reactions are rare enough that they remain in the case-report literature rather than appearing as a consistent signal in large trials, but they are worth knowing about because a new rash during Xgeva treatment should prompt consideration that the drug could be the cause.

Giant Cell Tumor of Bone

Xgeva is also approved for giant cell tumor of bone, a setting with its own distinct set of concerns. Giant cell tumor is a benign but locally aggressive bone tumor, and denosumab is used to shrink the tumor before surgery or in cases where surgery is not feasible. The drug is effective at inducing tumor regression, but a growing number of reports have described malignant transformation of giant cell tumors during denosumab treatment. Additionally, the morphological changes denosumab causes in the tumor tissue can overlap with what malignancy looks like under a microscope, creating diagnostic confusion for pathologists.

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The optimal duration of treatment, long-term safety, and best use-case criteria for denosumab in this setting remain unresolved. Clinical reviews have cautioned that the therapy should be applied carefully, particularly because stopping treatment can lead to tumor regrowth, creating a dilemma about how long to continue.

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Pregnancy and Reproductive Safety

Xgeva is not studied in pregnant women for obvious ethical reasons, but reproductive toxicity testing in monkeys has shown concerning results. When denosumab was given during pregnancy, a pre- and postnatal study in cynomolgus monkeys found increased stillbirths, one maternal death from difficulty during delivery, and in infants exposed in the womb, increased postnatal mortality, decreased weight gain, and abnormalities in bone and lymph nodes. Most of the bone-related changes in infants reversed by six months of age. The drug did not cause birth defects in a separate embryo-fetal development study, but the postnatal effects were considered consistent with the expected consequences of blocking RANKL during development.

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Given these findings, women of childbearing potential are advised to use effective contraception during treatment and for at least five months after the last dose. Xgeva is generally avoided in pregnancy unless the clinical situation leaves no alternative.

Why Some Patients Stop Treatment Early

In a real-world study examining denosumab use in cancer patients, the main reasons patients stopped treatment were disease progression (about 20%) and adverse events (25%). That one in four patients discontinued due to side effects highlights that while the drug is tolerable for many, a meaningful minority find the side effects burdensome enough to warrant stopping, even in the context of a serious cancer diagnosis where the stakes of untreated bone metastases are high.

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Reducing the Risks

Several of Xgeva’s most serious side effects are at least partially preventable with proactive management. The core recommendations are straightforward:

Calcium and vitamin D: Supplementation should begin before the first dose and continue throughout treatment, with regular blood monitoring to catch hypocalcemia early.
Dental care: A comprehensive dental exam before starting Xgeva, completion of any invasive dental procedures beforehand, and maintenance of good oral hygiene during treatment all reduce the risk of jaw osteonecrosis.
Communication between teams: Oncologists, dentists, and primary care providers need to coordinate, since the dentist may not know the patient is on Xgeva and the oncologist may not know the patient needs a tooth pulled.

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For patients who do develop jaw osteonecrosis, the prognosis is not uniformly grim. In the large integrated trial analysis, about 40% of cases in the denosumab group had resolved at the time of follow-up, and the vast majority were managed without major surgery.

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Patients on Xgeva should also report any new thigh or groin pain promptly, since catching an atypical femoral fracture while it is still incomplete prevents a far more painful and complicated complete fracture. And for anyone considering stopping Xgeva, a conversation about transitioning to a bisphosphonate to prevent the rebound effect is worth having with the treating oncologist before the last injection.