Background: Neutropenia is a common complication of cancer and cancer treatments. Granulocyte colony-stimulating factors (G-CSF) are medications that stimulate the bone marrow to produce neutrophils which are critical to treat and/or prevent febrile neutropenia, a potentially deadly complication of cancer. There are two FDA approved forms of G-CSF: filgrastim (Neupogen) and pegylated-filgrastim (Neulasta). Filgrastim is typically administered intravenously or subcutaneously daily for 10-14 days; pegfilgrastim is administered subcutaneously in a single dose once per chemotherapy cycle. The most prevalent and consistent side effect of G-CSF is bone pain. This Fast Fact will describe the symptoms, prevalence, potential etiology, and treatment of G-CSF-induced bone pain.

Clinical presentation: Pain typically begins 1-3 days after the first dose of a G-CSF, peaks at 3-5 days and resolves by day 7-8. The bone pain often is described as a deep ache which can be intermittent or constant and vary from mild to severe. Most often it is located where there is high bone marrow activity: the pelvis, lower back, sternum, ribs, and the long bones of the femur or humerus. It is typically highest after the first cycle of G-CSF and decreases or stabilizes after subsequent cycles.

Risk factors:  Patients younger than 55 are more likely to experience G-CSF-induced bone pain, but sex or type of cancer (e.g., solid tumor vs hematologic) do not appear to be risk factors (1). Filgrastrim and pegylated filgrastim have similar incidence of bone pain (65%) and severe bone pain (7%) (2,3). Taxanes (which are part of many chemotherapy regimens for breast, lung, prostate, gastric, and esophageal cancer) are associated with a similar syndrome – diffuse aching discomfort, most often in legs, hips, and lower back that evolves over 1 to 7 days – and it may not be possible to distinguish between them (4).

Causes: While the pathophysiology of G-CSF-induced bone pain is not fully understood, bone marrow expansion is considered the most likely cause. G-CSF causes rapid proliferation of myeloid progenitor cell colonies, increasing intraosseous pressure that stretches the periosteum and activates nearby nociceptive pain receptors, an inflammatory cascade, and consequently histamine levels (2,5).

Treatment : Most research on the treatment of G-CSF-induced bone pain is on pharmacologic prevention. 
Methods for this include:  

• Anticipatory guidance: Informing patients of the natural timeline and expected resolution of pain related to G-CSF can relieve stress and help patients cope with the pain. 
• G-CSF dose reduction: If a patient experiences a pattern of debilitating G-CSF induced bone pain, a dose reduction in subsequent cycles may be considered. Inform the treating oncology team and pharmacist if you suspect GSF-induced bone pain in a patient so they can consider this option.
• NSAIDs: Naproxen 500 mg twice daily for 5-8 days has been shown to be effective in reducing overall incidence, duration, and severity in G-CSF bone pain when initiated the morning before pegfilgrastrim in a phase 3 randomized controlled trial (6).  Notably, many patients receiving G-CSF stimulators have contraindications to NSAIDs – e.g., thrombocytopenia, renal impairment, and heart failure. So, while NSAIDs may be the most evidence-based pharmacotherapy for this type of pain, it is often not a practical choice for many patients.
• Acetaminophen: Based on its safety profile, acetaminophen is commonly used for G-CSF-induced bone pain in patients with solid tumors. However, patients who have a primary or secondary bone marrow disease (e.g. leukemias and lymphomas) are often already neutropenic or will become neutropenic. Thus, these patients are often counseled to avoid acetaminophen so that early warning signs of sepsis are not masked by acetaminophen (10).
• Antihistamines – case reports have described striking resolution of refractory pain from G-CSF induced bone pain with antihistamines such as loratadine 10 mg daily (5,7). Dual antihistamine blockade with both loratadine 10mg and famotidine 20mg when initiated 30 minutes before G-CSF has been associated with low cost, low risk, and significant reduction in pain scores (8).
• Opioids – In situations where patients have severe, refractory G-CSF induced pain and/or contraindications to the above therapies, it may be reasonable to prescribe short courses of opioids.
• Corticosteroids – While corticosteroids are routinely used in the treatment of bone pain in patients with cancer, there is no direct evidence suggesting their efficacy in G-CSF bone pain.

Expert opinion: All patients receiving G-CSF medications should be provided with anticipatory guidance about potential bone pain. Prophylactic prescription of an analgesic prior to the first dose of a G-CSF medication is recommend (9). However, these experts fall short of providing specific guidance on a particular analgesic. For patients with hematologic malignancies and severe neutropenia, NSAIDs and acetaminophen are often relatively contraindicated. Therefore, a one-week prophylactic administration of loratadine 10 mg and famotidine 20 mg daily, starting on the day of first G-CSF dose is a reasonable regimen. If this dual antihistamine regimen has not been effective enough in past rounds of G-CSF, then in opioid naive patients, a low-dose trial of a short-acting, as needed opioid may be reasonable.

References 

1. Tsuboi S, Hayama T, Miura K, et al. Higher incidence of pegfilgrastim-induced bone pain in younger patients receiving myelosuppressive chemotherapy: a real-world experience. J Pharm Health Care Sci. 2023;9(1):2.
2. Lambertini M, Del Mastro, Bellodi A, et al.  The five “Ws” for bone pain due to the administration of granulocyte-colony stimulating factors (G-CSFs).  Crit Rev Oncol Hematol 2014; 89(1):112-128.
3. Gregory SA, Mo M, Vogel C, et al.  Reported bone pain in cancer patients receiving chemotherapy in pegfilgrastim clinical trials: A retrospective analysis. Blood. 2009;114(22):4561-4561. doi:10.1182/blood.V114.22.4561.4561.
4. Loprinzi CL, Reeves BN, Dakhil SR, et al. Natural history of paclitaxel-associated acute pain syndrome: prospective cohort study NCCTG N08C1. J Clin Oncol. 2011;29(11):1472-1478.
5. Romeo C, Li Q, Copeland L. Severe pegfilgrastim-induced bone pain completely alleviated with loratadine: A case report. J Oncol Pharm Pract. 2015;21(4):301-304.
6. Kirshner JJ, Heckler CE, Janelsins MC, et al. Prevention of pegfilgrastim-induced bone pain: a phase III double-blind placebo-controlled randomized clinical trial of the university of rochester cancer center clinical community oncology program research base. J Clin Oncol. 2012;30(16):1974-1979.
7. Moore K, Haroz R. When Hydromorphone Is Not Working, Try Loratadine: An Emergency Department Case of Loratadine as Abortive Therapy for Severe Pegfilgrastim-Induced Bone Pain. J Emerg Med. 2017;52(2):e29-e31.
8. Ul Ain Azam N, Abdus Samad F, Syed AS, et al. Effect of Prophylactic Dual Histamine Blockade on Filgrastim-Induced Bone Pain in Female Cancer Patients: Single Institutional Analysis. J Pain Palliat Care Pharmacother. March 27, 2025:1-10.
9. Gascón P, Awada A, Karihtala P, Lorenzen S, Minichsdorfer C. Optimal use of granulocyte colony-stimulating factor prophylaxis to improve survival in cancer patients receiving treatment : An expert view. Wien Klin Wochenschr. 2024;136(11-12):362-368.
10. National Comprehensive Cancer Network. (2025). Adult Cancer Pain, Version 2.2025, NCCN Clinical Practice Guidelines In Oncology. Journal of the National Comprehensive Cancer Network, 23(7), e250032.

Author Affiliations:  University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania.
Version History: Originally electronically published in November 2025; first electronically edited by Sean Marks MD.
Conflicts of Interest: None to report.