Low white blood cells and infection risk
White blood cells fight germs. When they are low, you can get infections more easily, and infections can become serious quickly.
Why it happens
Many chemotherapy drugs lower white blood cells, often 7 to 14 days after treatment. Some targeted drugs, radiation to large bone areas, and blood cancers can also lower them.
What helps
- Wash your hands often, and ask others to wash theirs.
- Stay away from people who are sick, and avoid big crowds when your counts are low.
- Keep a working thermometer at home and know how to use it.
- Cook meat and eggs fully, and wash fruits and vegetables well.
- Ask your care team which vaccines are right for you and your family.
- Take good care of your teeth and skin, and clean any cuts right away.
Call your care team right away if you have
- You have a temperature of 100.4°F (38°C) or higher.
- You have chills or shaking, even without a fever.
- You have a new cough, burning when you urinate, or redness or pus around a cut or port.
Questions to ask
- When are my blood counts likely to be lowest?
- Do I need a medicine to help boost my white blood cells?
- What number on the thermometer should make me call you?
Medicines that can cause this
- Abemaciclib
- Acalabrutinib
- Antithymocyte globulin (ATG)
- Azacitidine
- Bendamustine
- Blinatumomab
- Brentuximab vedotin
- Busulfan
- CAR T-cell therapy
- Capecitabine
- Carboplatin
- Carfilzomib
- Cisplatin
- Cladribine
- Cyclophosphamide
- Cytarabine
- Dacarbazine
- Daratumumab
- Dasatinib
- Decitabine
- Elotuzumab
- Elranatamab
- Epcoritamab
- Eribulin
- Everolimus
- Fludarabine
- Fluorouracil (5-FU)
- Gemcitabine
- Glofitamab
- Hydroxyurea
Sources
Quick answers
- What is low white blood cells and infection risk during cancer treatment?
- White blood cells fight germs. When they are low, you can get infections more easily, and infections can become serious quickly.
- Why does low white blood cells and infection risk happen?
- Many chemotherapy drugs lower white blood cells, often 7 to 14 days after treatment. Some targeted drugs, radiation to large bone areas, and blood cancers can also lower them.
- What helps with low white blood cells and infection risk?
- Wash your hands often, and ask others to wash theirs; Stay away from people who are sick, and avoid big crowds when your counts are low; Keep a working thermometer at home and know how to use it; Cook meat and eggs fully, and wash fruits and vegetables well; Ask your care team which vaccines are right for you and your family; Take good care of your teeth and skin, and clean any cuts right away.
- When should I call my care team about low white blood cells and infection risk?
- You have a temperature of 100.4°F (38°C) or higher; You have chills or shaking, even without a fever; You have a new cough, burning when you urinate, or redness or pus around a cut or port.
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.