What is neutropenia?
Neutropenia is a fall in the number of neutrophils in the blood — the main defenders against bacteria and fungi. In leukemia and during its treatment, it is one of the most common and most important conditions. This topic covers how neutropenia is measured, when it happens, what risks it carries and how you can protect yourself.
01Short answer
02Simple explanation
The blood contains several kinds of white cells. The most numerous are neutrophils. They are the cells that first find and destroy bacteria and fungi entering the body. Neutrophils are short-lived, so the bone marrow replaces them every day.
Neutropenia means having fewer neutrophils than normal. Only a blood test shows it: neutropenia itself causes no pain or other sensation. A person can feel well while their defences are weak.
In leukemia, neutropenia has two main causes. First, leukemia cells take up space in the marrow and crowd out the production of healthy neutrophils. Second, chemotherapy and some other medicines temporarily stop fast-dividing cells, including the neutrophil “factory”.
When neutrophils are low, ordinary germs — even those living on our skin, in our mouth and in our gut — can cause infection. Infection can start quickly and spread fast, while the usual signs such as redness and pus are weak. That is why a fever is often the only signal.
The good news: after treatment the marrow usually recovers and neutrophils rise again. During this “low period”, simple habits — hand hygiene, safe food, keeping away from people who are ill and calling straight away with a fever — lower the risk considerably.
03Scientific explanation
The absolute neutrophil count (ANC) is calculated by multiplying the total white cell count by the proportion of neutrophils (segmented and band forms). Commonly used grades are: mild — 1.0–1.5×10⁹/L, moderate — 0.5–1.0×10⁹/L, severe — <0.5×10⁹/L; <0.1×10⁹/L is sometimes called “profound” neutropenia. Infection risk depends both on the ANC level and on the duration of neutropenia: severe neutropenia lasting more than 7 days is considered high risk.
Timeline: after chemotherapy the lowest neutrophil point (the nadir) often falls on days 7–12, and recovery takes a few weeks; the exact timing depends on the drugs and doses. During induction treatment for acute leukemia and during a transplant, neutropenia can last several weeks. Some people naturally have slightly lower neutrophil counts related to their ancestry (for example, the Duffy-null phenotype) — this does not mean a higher risk of infection, and doctors take it into account when interpreting results.
Prevention is chosen individually according to risk. Under ASCO/IDSA and NICE guidance, a preventive antibiotic — usually a fluoroquinolone — is considered for high-risk patients expected to have prolonged severe neutropenia (for example, in acute leukemia or a transplant); in some cases antifungal (for example, posaconazole) and antiviral prevention is also used. Growth factors (G-CSF: filgrastim, pegfilgrastim) shorten neutropenia with some regimens; whether to use them is decided by the doctor according to the type of leukemia and the treatment stage.
Febrile neutropenia, by the IDSA definition, is a single oral temperature of ≥38.3 °C or ≥38.0 °C sustained over an hour, with an ANC <0.5×10⁹/L (or expected to fall to this level within 48 hours). It is an emergency, and international guidelines (NICE, ESMO) recommend starting intravenous antibiotics as soon as possible after arrival — ideally within one hour. More details are in the next topic.
04What happens in the body?
When should you seek urgent help?
During neutropenia or in the weeks after chemotherapy, call your hematology team’s 24-hour number or emergency services straight away if: your temperature is 38 °C or higher (if your team has given a different threshold, follow it) or below 36 °C; you have shivering, chills, sudden weakness or confusion; you develop a cough, breathlessness, burning when passing urine, diarrhea, or sores in the throat or mouth; there is redness or discharge around a catheter. Do not wait and do not leave it “until the morning”.
How can I find out my neutrophil count?
On a complete blood count, neutrophils are shown both as a percentage and as an absolute number (ANC, “NEUT#” or a similar abbreviation). The key figure is the absolute number. Ask your team how often tests will be done and at what level extra precautions are needed. Writing results in a diary helps.
When does neutropenia happen?
After chemotherapy, neutrophils usually start to fall within a few days, reach their lowest point around days 7–12 and then gradually recover. With intensive treatment for acute leukemia this period can be longer. Your team will tell you your “most vulnerable days”.
What to pay attention to in daily life
Wash your hands often or use an alcohol hand rub. Prepare and cook food safely. Keep away from people with a fever, cough or diarrhea. Look after your mouth and use a soft toothbrush. Avoid damaging your skin; clean cuts and scratches. Keep a thermometer at home, and do not use rectal thermometers or suppositories.
How does recovery happen?
After a course of treatment the bone marrow usually starts working again and neutrophils begin to rise. Sometimes growth factor injections are prescribed to speed up recovery. The next course often starts once neutrophils have recovered enough.
Questions you can ask your doctor
How deep and how long will my neutropenia be? Which are my most vulnerable days? Do I need a preventive antibiotic, antifungal or growth factor? What temperature threshold and which phone number? Which foods should I avoid? Can I go to work, school or public places? When will my neutrophil count be checked again?
05The neutropenia period: step by step
After chemotherapy, neutropenia often follows a predictable path.
06Grades of neutropenia (ANC)
| Grade | ANC (×10⁹/L) | What does it mean? |
|---|---|---|
| Normal | above about 1.5 | Usual infection risk (laboratory limits may differ) |
| Mild | 1.0–1.5 | Slightly higher risk; usual precautions |
| Moderate | 0.5–1.0 | Higher risk; hygiene and food safety are especially important |
| Severe | below 0.5 | High risk; a fever is an emergency |
| Profound | below 0.1 | Very high risk, especially if it lasts more than 7 days |
* The limits are for general understanding and may differ slightly between sources. Your hematology team interprets your results.
07Key terms
- Neutrophil
- A white blood cell that is the main defender against bacteria and fungi.
- Neutropenia
- A lower-than-normal number of neutrophils in the blood.
- ANC
- Absolute neutrophil count — the key measure for judging neutropenia.
- Nadir
- The period when blood cells reach their lowest level after treatment.
- Febrile neutropenia
- A fever during neutropenia; an emergency.
- Neutropenic sepsis
- A severe form of infection during neutropenia that affects the whole body.
- G-CSF
- A growth factor that stimulates neutrophil production (for example, filgrastim).
- Prophylaxis
- Taking medicines in advance to prevent infection.
- Mucositis
- Damage to the lining of the mouth and gut; it can become a “door” for germs.
- Duffy-null phenotype
- An inherited trait that makes some people’s neutrophil count naturally a little lower.
08Key points
- Neutropenia is a fall in neutrophils.
- The key measure is the absolute neutrophil count (ANC).
- An ANC below 0.5×10⁹/L is severe neutropenia.
- After chemotherapy, the lowest point is usually around days 7–12.
- Neutropenia itself is not felt, but infection risk is high.
- A fever during neutropenia is an emergency.
- Hygiene, safe food and distance lower the risk.
- Your hematology team decides on preventive medicines.
09Frequently asked questions
Can food or vitamins raise my neutrophils?
No. Food and vitamins do not reverse neutropenia caused by treatment. Balanced nutrition matters for overall health, but neutrophil recovery depends mainly on the marrow itself recovering. Discuss supplements with your team.
Can I stay at home during neutropenia?
Many people spend the neutropenia period at home, especially with less intensive regimens. With intensive treatment for acute leukemia, this period is often spent in hospital. Either way, the rule of seeking help straight away with a fever does not change.
How often should I take my temperature?
Take it when you feel unwell, when you have chills and at the times your team recommends. To avoid “hiding” a fever, do not take fever-reducing medicines before measuring.
Does everyone get growth factor injections?
No. G-CSF is used with some regimens and in certain situations. Your hematology team decides whether it suits you, taking into account the type of leukemia and the treatment stage.
Can I have neutropenia even though leukemia raises my white cells?
Yes. Many of the white cells may be leukemia cells, while healthy neutrophils are few. That is why doctors look at the absolute neutrophil count rather than the total white cell count.
Can I live with my family during neutropenia?
Yes. Family members’ hand hygiene, keeping their distance when they are ill and being up to date with vaccinations help protect you. It can help to hand over some tasks, such as caring for pets, to someone else for a while.
10Questions for your doctor
Take these questions to your appointment. The ones you save are collected on the “My questions” page and stay on this device only.
What is my absolute neutrophil count (ANC) right now?
When will my neutrophils be at their lowest, and when will they recover?
What precautions should I take at home while neutropenic?
Do I need G-CSF (an injection to raise neutrophils)?
12Sources
- Centers for Disease Control and Prevention (CDC). Neutropenia and Risk for Infection
- National Cancer Institute (NCI). Infection and Neutropenia during Cancer Treatment
- American Cancer Society. Neutropenia (Low White Blood Cell Counts)
- MedlinePlus (U.S. National Library of Medicine). Low white blood cell count and cancer
- Cancer Research UK. Your blood, bone marrow and cancer drugs
- Cancer Research UK. Sepsis, infection, and cancer
- Blood Cancer UK. Blood cancer and infection
- StatPearls, NCBI Bookshelf. Febrile Neutropenia
- National Institute for Health and Care Excellence (NICE). Neutropenic sepsis: prevention and management in people with cancer (CG151)
- Journal of Clinical Oncology (ASCO and IDSA), 2018. Antimicrobial Prophylaxis for Adult Patients With Cancer-Related Immunosuppression: ASCO and IDSA Clinical Practice Guideline Update
- Clinical Infectious Diseases (IDSA), 2011. Clinical Practice Guideline for the Use of Antimicrobial Agents in Neutropenic Patients with Cancer: 2010 Update by the Infectious Diseases Society of America
- Annals of Oncology (ESMO), 2016. Management of febrile neutropaenia: ESMO Clinical Practice Guidelines
- Macmillan Cancer Support. Infection