Low Neutrophils (Neutropenia)
Neutrophils are the white blood cells that fight bacteria and fungi first. A mildly low count is common and often harmless, after a virus or simply as your normal. A very low count makes serious infections more likely.
Quick answer: Neutrophils under about 2.0 × 10⁹/L are low on most reports; neutropenia proper starts under 1.5. Mild drops often follow viruses or medicines, and many people of African or Middle Eastern ancestry naturally run lower. Under 0.5 is severe. Neutrophils under 0.5 with a temperature of 38°C or more is an emergency.
What the test measures
The full blood count reports each type of white blood cell. Neutrophils are usually the largest group and are the body’s first responders to bacterial and fungal infection. The important figure is the absolute neutrophil count, not the percentage.
Typical adult ranges
- Normal: about 2.0–7.5 × 10⁹/L (some labs use a lower limit of 1.5 or 1.8)
- US units: multiply by 1000 for cells per microlitre (2.0 × 10⁹/L is 2,000/µL)
- Mild neutropenia: 1.0–1.5
- Moderate: 0.5–1.0
- Severe: under 0.5
What a low result usually means
Common causes:
- A recent viral infection, such as flu, COVID-19 or glandular fever. Counts usually recover within weeks.
- Duffy-null associated neutrophil count (once called benign ethnic neutropenia): many people with African or Middle Eastern ancestry have the Duffy-null blood type and naturally lower, healthy neutrophil counts. In one US study, two-thirds of healthy Black adults were Duffy-null, and about 1 in 4 of them had counts under 2.0.
- Medicines: chemotherapy, carbimazole and propylthiouracil (for overactive thyroid), clozapine, methotrexate, sulfasalazine, some antibiotics such as trimethoprim-sulfamethoxazole, and others.
- Low B12, folate or copper.
- Alcohol, and an enlarged spleen.
- Autoimmune conditions such as lupus and rheumatoid arthritis.
Less common but important:
- Leukaemia, myelodysplasia, aplastic anaemia and other bone marrow problems, often with other abnormal counts.
- Severe infection or sepsis, which can use up neutrophils.
- Cyclic neutropenia and inherited forms, usually found in childhood.
Symptoms
A low count causes no symptoms by itself. When it’s very low, infections become more frequent or severe: fevers, mouth ulcers, sore throat, gum infections, skin infections or chest infections.
What happens next
- Repeat the full blood count with a blood film in a few weeks, especially after a virus.
- Review medicines, including recent antibiotics.
- Other tests may include B12, folate, copper, liver tests, HIV, hepatitis, and autoimmune tests.
- If your ancestry fits, Duffy-null testing can explain a lifelong lower count and spare you unnecessary tests.
- Haematology referral if the count stays under 1.0 without an explanation, keeps falling, or other blood counts are abnormal.
- With a very low count: good hand hygiene, food safety, and a thermometer at home.
Get urgent help (go to an emergency department or call 000 in Australia, or your local emergency number) if your neutrophils are under 0.5 × 10⁹/L, or you’re on chemotherapy, and you have a temperature of 38°C or more, shivers, or feel suddenly unwell: neutropenic sepsis can become life-threatening within hours. If you take carbimazole, propylthiouracil or clozapine and develop a sore throat, mouth ulcers or fever, get an urgent blood count and don’t take the next dose until a doctor says it’s safe.
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Common questions
Is a neutrophil count of 1.2 bad?
It’s mildly low. In someone who feels well it’s often from a recent virus or a medicine, or it may be a normal level for you, especially with African or Middle Eastern ancestry. Your GP will usually repeat it in a few weeks with a blood film.
What causes low neutrophils in adults?
The commonest causes are recent viral infections, medicines, and naturally lower counts linked with the Duffy-null blood type. Others include low B12 or folate, alcohol and autoimmune conditions. Bone marrow problems are less common and usually affect other counts too.
When is a low neutrophil count an emergency?
When it’s under 0.5 × 10⁹/L, or you’re having chemotherapy, and you have a temperature of 38°C or more or feel unwell. That’s neutropenic sepsis, which needs antibiotics within the hour, so go straight to an emergency department.
What is a Duffy-null associated neutrophil count?
It’s a healthy, lower neutrophil count seen in many people with the Duffy-null blood type, which is common in people with African or Middle Eastern ancestry. It doesn’t raise infection risk. It used to be called benign ethnic neutropenia.
Can stress cause low neutrophils?
Not usually. Stress hormones and steroid medicines tend to raise neutrophil counts rather than lower them. A low count is more likely to come from a virus, a medicine or your natural baseline.
How long does it take neutrophils to recover after a virus?
Usually a few weeks. That’s why doctors often repeat the count 2–6 weeks after you’ve recovered rather than testing straight away.
Evidence and more information
- Pathology Tests Explained (RCPA): White blood cell count and differential
- Kim, Forlini and Kremsreiter, American Family Physician 2025: Neutropenia, evaluation and management in primary care
- Gibson and Berliner, Blood 2014: How we evaluate and treat neutropenia in adults
- Merz et al, Blood Advances 2023: Absolute neutrophil count by Duffy status among healthy Black and African American adults
- NICE CG151: Neutropenic sepsis, prevention and management in people with cancer
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