Key points
- Filgrastim (Neupogen) is an injection that makes the bone marrow produce white blood cells (the soldiers that fight infection) [1].
- Its main use is preventing fever and infection in people having strong chemotherapy [1].
- In the original study, fever with low white blood cells was roughly halved with this drug [2].
- It is recommended when the chemotherapy regimen carries a high risk of fever (about 2 in 10 people or more) [3].
- It is started at least 24 hours after chemotherapy ends and must not be injected in the 24 hours before chemotherapy [1].
- The most common side effect is bone or back pain. Pain in the upper left abdomen or left shoulder may be a sign of spleen damage; seek help straight away [1].
What is this drug and how does it work?
For physicians
Filgrastim is a human granulocyte colony-stimulating factor produced by recombinant DNA technology in Escherichia coli. Its amino acid sequence is identical to the natural human form except for an extra methionine at the start of the chain [1]. Natural G-CSF regulates neutrophil production in the bone marrow and affects their proliferation, differentiation and some functions (such as phagocytosis); it has little direct effect on other blood cell lines [1].
After filgrastim is started, a transient rise in neutrophils is usually seen 1 to 2 days later; when it is stopped, circulating neutrophils usually fall by 50% within 1 to 2 days and return to pre-treatment levels within 1 to 7 days [1]. Its elimination half-life is about 3.5 hours, which is why it is injected daily [1]. Filgrastim was first approved in the United States in 1991 [1].
Which cancers is it used for?
Your doctor may prescribe this drug for:
- Non-myeloid cancers (solid tumours, lymphoma) with chemotherapy that suppresses the bone marrow
- Acute myeloid leukaemia (AML) after induction or consolidation chemotherapy
- Non-myeloid cancers with myeloablative chemotherapy and bone marrow transplantation
- Collecting blood stem cells for an autologous transplant
- Severe chronic neutropenia (congenital, cyclic or idiopathic) with symptoms
- Acute exposure to marrow-suppressing doses of radiation (acute radiation syndrome)
Whether it suits you depends on the type and stage of your cancer and your test results. Details of each use are in the section for doctors.
For physicians
| Use | Aim |
|---|---|
| Non-myeloid cancers (solid tumours, lymphoma) with myelosuppressive chemotherapy | Reduce infection, as shown by febrile neutropenia |
| Acute myeloid leukaemia (AML) after induction or consolidation chemotherapy | Shorten time to neutrophil recovery and duration of fever |
| Non-myeloid cancers with myeloablative chemotherapy and bone marrow transplantation | Reduce the duration of neutropenia and its complications |
| Collection of peripheral blood stem cells for autologous transplantation | Mobilise stem cells from the bone marrow into the blood for collection by apheresis |
| Severe chronic neutropenia (congenital, cyclic or idiopathic) with symptoms | Reduce infections, fever and mouth ulcers |
| Acute exposure to myelosuppressive doses of radiation (acute radiation syndrome) | Improve survival |
All uses in this table are in the FDA label [1].
| Use | Key evidence |
|---|---|
| Non-myeloid cancers (solid tumours, lymphoma) with myelosuppressive chemotherapy | Randomised double-blind trial in small cell lung cancer: febrile neutropenia 40% vs 76% [1, 2] |
| Acute myeloid leukaemia (AML) after induction or consolidation chemotherapy | Median severe neutropenia 14 vs 19 days with placebo; no difference in complete remission or survival [1] |
| Non-myeloid cancers with myeloablative chemotherapy and bone marrow transplantation | Significantly fewer days of severe neutropenia in randomised lymphoma trials [1] |
| Collection of peripheral blood stem cells for autologous transplantation | FDA label [1] |
| Severe chronic neutropenia (congenital, cyclic or idiopathic) with symptoms | FDA label [1] |
| Acute exposure to myelosuppressive doses of radiation (acute radiation syndrome) | Based on animal studies, because human studies were not possible [1] |
In a systematic review of 17 randomised trials, prophylactic G-CSF lowered the risk of febrile neutropenia by 46%, infection-related mortality by 45% and early mortality by 40% [4].
Guidelines: primary prophylaxis when the risk of febrile neutropenia is about 20% or more and no equally effective regimen without CSF exists, or in high-risk patients based on age, medical history, disease characteristics and the myelotoxicity of the regimen (ASCO) [3]; the EORTC guideline gives a similar risk-based approach [5].
How it is taken and dosing
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Treatment regimens and doses: index5 regimens
- Filgrastim is given as a daily injection under the skin (or sometimes into a vein). Suitable sites for injection under the skin: the outer upper arm, abdomen, thigh or upper outer buttock [1].
- If you or a family member give the injections, you must first be taught by the healthcare team and follow the instructions for the vial or prefilled syringe [1].
- Injections usually start at least 24 hours after chemotherapy and continue for as long as your doctor decides from blood tests (usually up to two weeks) [1]. Even if your blood count goes up after a day or two, do not stop the drug on your own; this early rise is temporary [1].
- During treatment, a full blood count is usually done twice a week [1].
- Take the drug out of the fridge 30 minutes before injecting so it reaches room temperature. Do not shake it. Do not use it if the solution is cloudy, discoloured or contains particles. Throw away what is left in the vial or syringe [1].
- If you miss a dose, contact your doctor or nurse [1].
- Before starting and monitoring: CBC and platelets before starting and at least twice a week during treatment with chemotherapy [1].
- Injection: subcutaneously in the upper arm, abdomen, thigh or upper outer buttock; let it reach room temperature 30 minutes before injecting (no more than 24 hours out of the fridge). For IV infusion, dilute only in 5% dextrose (never sodium chloride); at concentrations of 5 to 15 µg/mL, add human albumin to a final concentration of 2 mg/mL [1]. Presentations: vials of 300 µg/1 mL and 480 µg/1.6 mL; prefilled syringes of 300 µg/0.5 mL and 480 µg/0.8 mL [1].
- Discontinue or interrupt: discontinue permanently for a serious allergic reaction; discontinue in ARDS and sickle cell crisis; interrupt for cutaneous vasculitis (resume at a lower dose after recovery); with likely glomerulonephritis, reduce or interrupt the dose. Upper left abdominal or shoulder pain: assess for splenic enlargement or rupture [1].
- Kidney and liver: no dose adjustment needed [1].
For physicians
Standard dosing (FDA label)
Myelosuppressive chemotherapy (non-myeloid tumours) or AML (induction/consolidation)
Prevention or reduction of chemotherapy-induced neutropenia
Prevention or reduction of chemotherapy-induced neutropenia [1]
Before prescribing: Shared safety points| Drug | Dose | Route | Schedule |
|---|---|---|---|
| Each chemotherapy cycle | |||
| Filgrastim | 5 µg/kg daily (starting dose) | Subcutaneous, short IV infusion over 15 to 30 minutes, or continuous IV infusion | Once daily; start at least 24 hours after chemotherapy |
Do not give in the 24 hours before chemotherapy. A transient neutrophil rise 1 to 2 days after starting is normal; do not stop early. Dose increases of 5 µg/kg per cycle may be considered according to the duration and severity of the ANC nadir; stop if ANC exceeds 10,000/mm³ after the nadir [1].
Bone marrow transplantation
Non-myeloid cancers with myeloablative chemotherapyCycle length: Daily
Non-myeloid cancers with myeloablative chemotherapy [1]
Before prescribing: Shared safety points| Drug | Dose | Route | Schedule |
|---|---|---|---|
| After transplant | |||
| Filgrastim | 10 µg/kg daily | IV infusion over up to 24 hours | First dose at least 24 hours after chemotherapy and 24 hours after the bone marrow infusion |
ANC above 1000/mm³ for 3 consecutive days: reduce to 5 µg/kg daily; if it stays above 1000 for 3 more consecutive days: stop; if it then falls below 1000: resume at 5 µg/kg daily. If ANC falls below 1000 during the 5 µg/kg dose, return to 10 µg/kg. Monitor CBC and platelets frequently [1].
Peripheral blood stem cell mobilisation (autologous)
Before apheresisCycle length: Daily
Before apheresis [1]
Before prescribing: Shared safety points| Drug | Dose | Route | Schedule |
|---|---|---|---|
| Mobilisation | |||
| Filgrastim | 10 µg/kg daily | Subcutaneous | Once daily |
Check the neutrophil count after 4 days; stop if WBC exceeds 100,000/mm³ [1].
Severe chronic neutropenia
After confirming the diagnosis with serial CBCs, bone marrow morphology and karyotypeCycle length: Daily and chronic
After confirming the diagnosis with serial CBCs, bone marrow morphology and karyotype [1]
Before prescribing: Shared safety points| Drug | Dose | Route | Schedule |
|---|---|---|---|
| Congenital | |||
| Filgrastim | 6 µg/kg | Subcutaneous | Twice daily (starting dose) |
| Cyclic or idiopathic | |||
| Filgrastim | 5 µg/kg | Subcutaneous | Once daily (starting dose) |
CBC with differential and platelets during the first 4 weeks and 2 weeks after each dose change, then monthly in the first year [1].
Acute radiation syndrome (haematopoietic syndrome)
Radiation exposure above 2 GyCycle length: Daily
Radiation exposure above 2 Gy [1]
Before prescribing: Shared safety points| Drug | Dose | Route | Schedule |
|---|---|---|---|
| As soon as possible after exposure | |||
| Filgrastim | 10 µg/kg | Subcutaneous | Once daily |
Baseline CBC, then about every 3 days; do not delay administration while waiting for a CBC [1].
Doses follow the trial protocol, guideline or official drug label (source given in the notes of each regimen). Before prescribing, check blood counts, renal and hepatic function, drug interactions and the patient’s condition, and adjust the dose according to the drug label.
Side effects
Common side effects
For physicians
In placebo-controlled trials in patients receiving chemotherapy, the most common adverse reactions occurring at least 5% more often than with placebo were pyrexia, pain, rash, cough and dyspnoea [1]. Bone pain is a known effect of G-CSF; in the pivotal trial, mild to moderate medullary bone pain occurred in 20% of patients [2], and in a systematic review of trials, bone or musculoskeletal pain was reported in 19.6% of G-CSF recipients vs 10.4% of controls [4]. In patients receiving filgrastim for stem cell collection, bone pain, fever and headache are the most common adverse reactions [1].
| Adverse reaction | Filgrastim (294 patients) | Placebo (157 patients) |
|---|---|---|
| Pyrexia | 48% | 29% |
| Nausea | 43% | 32% |
| Fatigue | 20% | 10% |
| Back pain | 15% | 8% |
| Dizziness | 14% | 3% |
| Cough | 14% | 8% |
| Rash | 14% | 5% |
| Chest pain | 13% | 6% |
| Dyspnoea | 13% | 8% |
| Pain | 12% | 6% |
| Bone pain | 11% | 6% |
| Arthralgia | 9% | 2% |
Laboratory abnormalities in the same trials: thrombocytopenia 38% vs 29% and raised LDH and alkaline phosphatase each 6% vs 1% [1]. Data from three randomised placebo-controlled trials in small cell lung cancer and non-Hodgkin lymphoma [1]. Some of these reactions may relate to the disease or the chemotherapy.
Serious side effects
These are less common but serious; tell your team early if you notice any sign of them:
- An enlarged or ruptured spleen (rare): pain in the upper left abdomen or left shoulder; go to the emergency department straight away [1].
- A severe lung problem: severe shortness of breath or fast breathing with fever [1].
- A severe allergic reaction: facial swelling, widespread hives or shortness of breath, mostly with the first injection [1].
- Kidney inflammation: swelling of the face or ankles, dark urine or passing little urine [1].
- Fluid leaking from the blood vessels: sudden swelling, dizziness or low blood pressure [1].
- In sickle cell disease, a severe pain crisis [1].
For physicians
Serious adverse reactions are rare but should be recognised [1]:
- Splenic enlargement or rupture, including fatal cases; with upper left abdominal or left shoulder pain.
- Acute respiratory distress syndrome (ARDS); with fever and dyspnoea.
- Serious allergic reactions including anaphylaxis, mostly on first exposure and possibly recurring days after initial treatment.
- Severe and sometimes fatal sickle cell crises in people with sickle cell disorders.
- Glomerulonephritis; with facial or ankle swelling, dark or bloody urine, or reduced urine output.
- Capillary leak syndrome; with hypotension, oedema and hypoalbuminaemia, which can be life-threatening if treatment is delayed.
- Myelodysplastic syndrome and acute myeloid leukaemia in breast and lung cancer patients who received filgrastim with chemotherapy or radiotherapy, and in congenital neutropenia.
- Leucocytosis (100,000/mm³ or more in about 2% of patients at doses above 5 µg/kg) and thrombocytopenia.
- Cutaneous vasculitis and large- and medium-vessel arteritis including aortitis, which can present from the first week of treatment with fever, abdominal pain, back pain, headache or neck pain.
- Pulmonary haemorrhage and haemoptysis in healthy stem cell donors (an unapproved use).
When should I call my doctor?
Call your doctor or go to the emergency department straight away if you have [1]:
- Pain in the upper left abdomen or left shoulder (possible enlarged or ruptured spleen).
- Shortness of breath, with or without fever.
- A rash, facial swelling, wheezing, shortness of breath, dizziness or palpitations (an allergic reaction).
- Swelling of the face or ankles, dark or bloody urine, or passing less urine.
- Purple spots or redness of the skin (possible vasculitis).
- Fever, abdominal pain, back pain, headache or neck pain without a clear cause (possible arteritis).
- Tiredness, fever and bruising or bleeding easily.
Also remember: any temperature of 38 °C or higher during chemotherapy, even while taking filgrastim, is an emergency [7].
Interactions, pregnancy and precautions
- When not to use it: a past serious allergic reaction to filgrastim, pegfilgrastim or similar medicines that raise white blood cells [1].
- Timing with chemotherapy and radiotherapy: because the fast-dividing cells of the bone marrow are sensitive, it should not be injected from 24 hours before to 24 hours after chemotherapy; using it at the same time as chemotherapy and radiotherapy is not recommended [1].
- Drug interactions: the official prescribing information has no separate section on drug interactions; even so, give your doctor a list of all your medicines.
- Pregnancy: studies that followed pregnant women have shown no link between filgrastim in pregnancy and major birth defects, miscarriage or harm to the mother or baby [1]. Tell your doctor if you are pregnant or planning a pregnancy.
- Breastfeeding: filgrastim has been reported to pass into breast milk; in a few reports of single cases, no side effect was seen in the baby. The decision is made by weighing the benefits and risks [1].
- Latex allergy: the needle cover of the prefilled syringe contains dry natural rubber (latex); people who are allergic to latex should not inject from the prefilled syringe [1].
- Storage: in the fridge (2 to 8 °C), in the original box, away from light. Do not freeze it; if it freezes once, thaw it in the fridge, but if it freezes more than once, throw it away. A vial or syringe left at room temperature for more than 24 hours must be thrown away [1].
- Bone scans: the extra activity of the bone marrow may cause short-lived changes on bone imaging; if you are having a scan, tell your doctor that you are taking filgrastim [1].
- Biosimilars (close copies of the original medicine): in a large study in breast cancer, a biosimilar filgrastim shortened the time with very low white blood cells as well as the original medicine (Neupogen), and there was no meaningful difference between them in how well they worked or how safe they were [6].
Frequently asked questions
Why do my bones ache after filgrastim injections?
What is the difference between filgrastim and pegfilgrastim?
Does filgrastim make cancer grow?
The G-CSF receptor has been found on some tumour cell lines, and the FDA label does not rule out a growth effect on tumours [1]. In a review of studies, preventive G-CSF reduced early deaths and deaths from infection, but the data were not enough to judge its effect on cancer coming back or on survival [4].
What should I do if I forget an injection?
Contact your doctor or nurse for advice on how to continue [1].
Scientific evidence
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Key studies
1 itemReduction by Granulocyte Colony-Stimulating Factor of Fever and Neutropenia Induced by Chemotherapy in Patients with Small-Cell Lung Cancer
Related cancer types
References
7 referencesShow all references, 5 with a study cardClose the reference list
Numbers in the text, such as [1], refer to these sources. Sources with a “Study card” button are summarised in the site’s evidence library.
- 1NEUPOGEN (filgrastim) injection, for subcutaneous or intravenous use — Prescribing Information
- 2
- 3
- 4
- 52010 update of EORTC guidelines for the use of granulocyte-colony stimulating factor to reduce the incidence of chemotherapy-induced febrile neutropenia in adult patients with lymphoproliferative disorders and solid tumours
- 6Comparison of EP2006, a filgrastim biosimilar, to the reference: a phase III, randomized, double-blind clinical study in the prevention of severe neutropenia in patients with breast cancer receiving myelosuppressive chemotherapy
- 7Infection and Neutropenia during Cancer Treatment
This page is based on reputable scientific sources and was last updated on 28 October 2026. The content of this website is for educational and informational purposes only and does not replace consultation, diagnosis or treatment by a specialist physician. Consult your treating physician about any treatment decision.
Printed from the website; the full and up-to-date version: https://drdabiri.com/en/drugs/filgrastim/