Neutropenic Fever During Cancer Treatment

Neutropenic fever means a fever at a time when infection-fighting white blood cells may be low. Cancer teams treat this carefully. Infection risk can change quickly during chemotherapy, transplant, and some other treatments.

Clinicians use a specific definition. StatPearls describes neutropenic fever as a single oral temperature of 101°F (38.3°C) or above, or a temperature of 100.4°F (38°C) held for at least an hour, in someone with an absolute neutrophil count below 1,500 cells per microlitre. Below 500 is called severe neutropenia. Below 100 is called profound neutropenia. Treatment guidelines draw the line tighter than StatPearls does: they generally reserve the label for an ANC under 500, or under 1,000 and expected to fall below 500. None of that changes what you do. The count is a laboratory result you will not have at home, so the fever is your trigger, and your own team may give you a lower temperature to call about. Use their number.

This page is a planning aid. It cannot diagnose the cause of a symptom. It cannot replace the instructions from your oncology team.

Someone with low neutrophils may not show the usual early signs of infection. So the care team may need more to go on. That includes the treatment schedule, blood counts, temperature pattern, medicines, and other symptoms.

Many treatment side effects are easier to handle when the team hears about them early. If your team already gave you an urgent call plan, use that plan first.

• Temperature readings and times, if your team told you to measure them.
• The date of your last chemotherapy, transplant, or immune-weakening treatment.
• Your most recent white blood cell or neutrophil result, if you have it.
• Chills, shaking, cough, pain, urinary symptoms, rash, dizziness, or confusion.
• Antibiotics, steroids, fever reducers, or other medicines already taken.

• What is the most likely cause in my situation, and what else needs to be ruled out?
• Which symptoms or changes mean same-day contact for my exact treatment?
• What information should I track before I call or come in?
• Could this affect treatment timing, dose, or supportive medicines?
• Who should I contact after hours, and what should I say first?

The plan may involve same-day evaluation, lab work, cultures, imaging, or medicines. It may also change treatment timing, or lead to closer monitoring. The important point is not to self-diagnose the cause of the fever.

Ask what result or symptom pattern would change the plan. Ask what can be watched, and what should not wait until the next routine visit.

• Do not assume a symptom is "just treatment" without checking the plan your team gave you.
• Do not assume the same symptom means the same thing for every cancer treatment.
• Do not start a new over-the-counter medicine, supplement, or major diet change without asking the care team while symptoms are active.

Neutropenic fever is a medical emergency. Antibiotics work best when they are given within the first hour, and delay raises the risk of dying from the infection. Nothing on this page should be watched overnight.

• Call 911 or go to an emergency department if you have a fever together with confusion, drowsiness you cannot shake off, dizziness or feeling faint, fast breathing, trouble breathing, or shaking chills. These suggest the infection is affecting blood pressure and organs.
• Go to an emergency department if you cannot reach your care team quickly and you have a temperature of 100.4°F (38°C) or higher during or after chemotherapy, a transplant, or another immune-weakening treatment. Say at the desk that you are having chemotherapy and may be neutropenic.
• Call your care team immediately, at any hour, if your temperature is 100.4°F (38°C) or higher. Do not take paracetamol, acetaminophen, ibuprofen, or another fever reducer first unless your team told you to. It can hide the fever without treating the cause.
• Call your care team the same day if you feel unwell without a fever and have a new cough, sore mouth or throat, burning on passing urine, diarrhea, a rash, or pain, redness, or discharge around a central line or port. Low neutrophils can blunt the usual signs of infection, so a low-grade change matters more than usual.
• Call your care team the same day if you have a temperature below that level but your team gave you a different threshold. Their number is the one to use.

Helpful next pages include Fever During Chemo: What to Know, Low White Blood Cells During Chemotherapy, Neutropenia During Chemotherapy, Side Effects of Cancer Treatment.

• StatPearls (NCBI Bookshelf) — Neutropenic Fever, accessed August 11, 2026