Febrile neutropenia !

Fever in someone with very few infection-fighting white cells, usually after chemotherapy. It is an emergency that needs antibiotics within an hour.

Updated 2026-11-01

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Why it happens

What it is

Fever in a patient with a low absolute neutrophil count, most often after cancer chemotherapy. Widely used definitions are a single oral temperature of 38.3 °C or more, or 38.0 °C or more sustained for an hour, with neutrophils below 500/µL or expected to fall below that within 48 hours. It is an oncologic emergency.

Who gets it

One of the most frequent complications of chemotherapy, especially in acute leukaemia, lymphoma and intensive regimens for solid tumours. In Colombia and the rest of Latin America it is a leading reason for emergency visits and deaths during childhood cancer treatment, and local resistance patterns of gram-negative bacteria guide empirical antibiotics.

Causes

Chemotherapy-induced marrow suppression, usually 7 to 14 days after a cycle (the nadir)
Marrow infiltration by leukaemia, lymphoma or other cancers
Infection from the patient's own flora: gram-negative bacilli (including Pseudomonas), gram-positive cocci from skin and catheters
Fungi (Candida, Aspergillus) with prolonged neutropenia
Often no organism is found

Risk factors

Intensive chemotherapy, especially for acute leukaemia and stem cell transplant
Expected neutropenia longer than 7 days
Central venous catheter
Mucositis and broken skin
Older age, comorbidities and poor nutrition

Pathophysiology

Neutrophils are the first defence against bacteria and fungi. When they are absent, organisms from the gut, mouth and skin cross damaged barriers (mucositis, catheters) into the blood and can cause sepsis within hours. Because there are no neutrophils to make an inflammatory response, the usual signs of infection (pus, infiltrates on X-ray, urinary white cells) may be missing, and fever may be the only sign.

Classification

Low risk: short expected neutropenia, stable, few comorbidities (e.g. high MASCC score); may receive oral antibiotics as outpatients in selected settings
High risk: prolonged neutropenia, haemodynamic instability, organ dysfunction, mucositis, pneumonia or catheter infection; inpatient intravenous treatment

Symptoms and signs

Fever, sometimes with chills or rigors
Few or no localising signs; minimal redness or pus
Sore mouth, cough, pain at a catheter site, abdominal pain or diarrhoea pointing to a source
Malaise and fatigue

Diagnosis

Clinical: Ask about the date of the last chemotherapy and examine mouth, skin, catheter sites, lungs, abdomen and perianal area (inspection only; digital rectal examination is avoided). Assess risk with a validated score.
Tests: Complete blood count with absolute neutrophil count, at least two sets of blood cultures (from the catheter and a peripheral vein) taken before antibiotics, urine culture, kidney and liver function, lactate, and cultures from any clinical site.
Imaging: Chest X-ray if respiratory signs; CT of chest, sinuses or abdomen when pneumonia, fungal infection or typhlitis is suspected despite a normal X-ray.

Differential diagnosis

Drug fever or transfusion reaction
Tumour fever (lymphoma, leukaemia)
Thrombophlebitis or deep vein thrombosis
Engraftment syndrome after stem cell transplant
Viral infection (including endemic infections such as dengue)

Goal of treatment

Start effective empirical antibiotics within one hour of arrival, find and treat the source, and support the patient until neutrophils recover.

Treatment

Acute: Empirical broad-spectrum intravenous antibiotic with anti-pseudomonal activity (e.g. an anti-pseudomonal cephalosporin, piperacillin-tazobactam or a carbapenem) started within 60 minutes, after cultures are drawn.
Medical: Add anti-MRSA coverage (e.g. vancomycin) for catheter or skin infection, pneumonia or haemodynamic instability; add empirical antifungal treatment if fever persists for 4 to 7 days of antibiotics.
Acute: Sepsis management: fluid resuscitation, vasopressors and intensive care when needed; removal of an infected catheter in selected cases.
Medical: Granulocyte colony-stimulating factor is used mainly to prevent neutropenia with high-risk chemotherapy regimens.
Follow-up: Neutropenic precautions: strict hand hygiene, single room when possible, no visitors with infections, no rectal temperatures or suppositories, careful food safety, oral hygiene, and close monitoring of temperature and vital signs.

Drugs for this condition

Complications

Bacteraemia, sepsis and septic shock
Pneumonia and invasive fungal infection (aspergillosis, candidaemia)
Neutropenic enterocolitis (typhlitis)
Catheter-related bloodstream infection
Delays or dose reductions in cancer treatment

Prognosis

With prompt antibiotics most episodes resolve as neutrophils recover. Mortality rises steeply with delays in treatment, septic shock, gram-negative bacteraemia, invasive fungal infection and prolonged neutropenia.

Test yourself

Think of the answer, then tap the question to see it.

How is febrile neutropenia defined?

Temperature of 38.3 °C once or 38.0 °C sustained for an hour, with neutrophils below 500/µL or expected to fall below 500/µL within 48 hours.

When should antibiotics be started in febrile neutropenia?

Within 60 minutes of presentation, after blood cultures are drawn; cultures must not delay treatment.

Why may a neutropenic patient with pneumonia have a nearly normal chest X-ray?

Without neutrophils there is little inflammatory response, so infiltrates, pus and other classic signs may be absent.

What are two nursing neutropenic precautions?

Strict hand hygiene and avoiding rectal temperatures or suppositories; also a single room, no sick visitors and careful food safety.

When does the neutrophil nadir usually occur after chemotherapy?

About 7 to 14 days after the start of a chemotherapy cycle.

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Educational information, not medical advice. For any symptom, see a health professional.

Sources: Low white blood cell count and cancer (MedlinePlus (U.S. National Library of Medicine), 2025).

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