Why have you been prescribed Neupogen

What is Neutropenia?

White blood cells, the majority of which are called neutrophils, are one of the main cells that fight bacteria when it enters your body.1
Chemotherapy can cause a reduction in the number of neutrophils in your body.3 This is called neutropenia, which can sometimes lead to infection because you have fewer neutrophils available to fight off bacteria.1
Infection can be one of the most serious side effects of chemotherapy.2 It may need to be treated in hospital and can disrupt your schedule for chemotherapy.
Chemotherapy works by killing fast-growing cancer cells.
Chemotherapy drugs can’t tell the difference between cancer cells and fast-growing healthy cells. A possible side effect of chemotherapy is a low count of neutrophils.2
Chemotherapy -1
Having a low neutrophil count is a condition known as neutropenia.
Neutropenia can increase your risk of developing certain types of infections. A low white blood cell count with fever, also known as febrile neutropenia, can be a sign of a serious infection.2 You should call your doctor or nurse right away if you get a fever higher than 38°C.4
Infection may be a risk throughout your chemotherapy treatment.
Your treatment plan may consist of multiple chemotherapy cycles. The risk of infection may be present in every one of them. Helping to reduce that risk should be an important consideration for you and your doctor/nurse.

Why have you been prescribed Neupogen®?

Neupogen® may increase your number of white blood cells (neutrophils) following chemotherapy. This increase in neutrophils may help in preventing infection.5
Before chemotherapy:
At natural levels, white blood cells such as neutrophils help protect your body against infection.
With chemotherapy:
Chemotherapy can reduce your neutrophil count. This may put you at risk for certain types of infection.
After chemotherapy:
Neupogen® can help stimulate the production of neutrophils, shortening the time and reducing the depth of a low white blood cell count after chemotherapy. This can help your body fight infection.5
Neupogen® can also be used:5
  • to increase the number of white blood cells (neutrophils) after a bone marrow transplant to help prevent infections;
  • before high-dose chemotherapy to make the bone marrow produce more stem cells which can be collected and given back to you after your treatment. These can be taken from you or from a donor. The stem cells will then go back into the bone marrow and produce blood cells;
  • to increase the number of white blood cells (neutrophils) if you suffer from severe chronic neutropenia to help prevent infections;
  • in patients with advanced HIV infection to help reduce the risk of infection.

How does Neupogen® work?

The body makes G-CSF

The body makes a natural protein called G-CSF (granulocyte colony stimulating factor) which acts in the bone marrow to boost the production of white blood cells called neutrophils.

Neupogen® is a form of G-CSF

Like G-CSF, Neupogen® acts in the bone marrow, where it helps boost the production of neutrophils.

Neutrophils may mature faster

Neupogen® can help neutrophils to mature faster so they are ready for release into the blood stream to help fight bacteria and may help to reduce the risk of infection.


  1. American Cancer Society. Why People with Cancer are More Likely to Get Infections. [Available at: https://www.cancer.org/treatment/treatments-and-side-effects/physical-side-effects/low-blood-counts/infections/why-people-with-cancer-are-at-risk.html. Accessed: January 2021]
  2. American Cancer Society. Causes of Infections. [Available at: https://www.cancer.org/treatment/treatments-and-side-effects/physical-side-effects/low-blood-counts/infections/risk-for-infections.html. Accessed: January 2021]
  3. American Cancer Society. Chemotherapy Side Effects. [Available at: https://www.cancer.org/treatment/treatments-and-side-effects/treatment-types/chemotherapy/chemotherapy-side-effects.html. Accessed: January 2021]
  4. NHS. Low white blood cell count. [Available at: https://www.nhs.uk/conditions/low-white-blood-cell-count/. Accessed: January 2021]
  5. Neupogen® (filgrastim). Patient Information Leaflet. [Available at: www.medicines.ie/medicines/list/all/page-1/per-page-25?query=neupogen]