Fever with low white blood cells (febrile neutropenia)
A fever when your white blood cells are low is a medical emergency. Your body may not be able to fight an infection on its own.
Why it happens
It happens most often after chemotherapy, when a type of white blood cell called neutrophils drops. People with blood cancers or after stem cell transplant are at higher risk.
What helps
- Save your care team's 24-hour phone number in your phone and on your fridge.
- Check your temperature any time you feel warm, chilled, or unwell.
- Do not take acetaminophen or ibuprofen for a fever until you have called your care team. These can hide a fever.
- If you go to the emergency room, say right away that you are getting chemotherapy.
- Carry a wallet card or note that lists your cancer, your treatment, and your oncologist's name.
Call your care team right away if you have
- Call right away, day or night, if your temperature is 100.4°F (38°C) or higher.
- Call right away if you have shaking chills, feel confused, or feel very unwell.
- Call 911 if you have trouble breathing, feel faint, or cannot stay awake.
Questions to ask
- Who do I call after hours, and where should I go if I have a fever?
- Should I have antibiotics at home just in case?
- Is there a fever card or letter I can bring to the emergency room?
Sources
Quick answers
- What is fever with low white blood cells during cancer treatment?
- A fever when your white blood cells are low is a medical emergency. Your body may not be able to fight an infection on its own.
- Why does fever with low white blood cells happen?
- It happens most often after chemotherapy, when a type of white blood cell called neutrophils drops. People with blood cancers or after stem cell transplant are at higher risk.
- What helps with fever with low white blood cells?
- Save your care team's 24-hour phone number in your phone and on your fridge; Check your temperature any time you feel warm, chilled, or unwell; Do not take acetaminophen or ibuprofen for a fever until you have called your care team. These can hide a fever; If you go to the emergency room, say right away that you are getting chemotherapy; Carry a wallet card or note that lists your cancer, your treatment, and your oncologist's name.
- When should I call my care team about fever with low white blood cells?
- Call right away, day or night, if your temperature is 100.4°F (38°C) or higher; Call right away if you have shaking chills, feel confused, or feel very unwell; Call 911 if you have trouble breathing, feel faint, or cannot stay awake.
Last updated: 2026-10-27. Medically reviewed by Veli Bakalov, MD, medical oncologist (October 2026). General education from Step by Step, the patient portal of HemeOncBuddy.