Low White Blood Cells During Chemotherapy

This page is for people on chemotherapy, and their caregivers, who have been told their white blood cells are low. It explains which number matters, what the cutoffs mean, and when to call for help.

Your report shows a total white blood cell count. That is not the only number your team is watching.

Neutrophils are a type of white cell that helps fight infection. What matters most is the absolute neutrophil count, written ANC. ACS explains that the ANC is the number of neutrophils, not the percentage. Your lab report shows it next to the total count.

Ask for your ANC by name. "My counts were a bit low" is not a usable answer.

ACS lists chemotherapy as a common cause of low neutrophils. Cancers that affect the bone marrow, such as leukemia and lymphoma, can also cause it.

The timing follows a pattern within a cycle. ACS says the lowest point, called the nadir, often comes about 7 to 10 days after chemo. Blood counts after chemo: a timeline covers when the dip usually arrives and when it recovers.

Once you know your ANC, the next question is what counts as low. Each lab sets its own normal range, so ask what yours uses.

MedlinePlus, writing for patients, says that in general an adult with fewer than 1,000 neutrophils per microliter has neutropenia. Fewer than 500 is called severe neutropenia. The lower your count, the higher your risk of infection, so these numbers guide how quickly your team wants to hear from you.

A fever while your counts are low is the sign that turns a phone call into an emergency.

Federal patient pages differ slightly on the fever threshold. MedlinePlus, CDC and ACS use 100.4°F (38°C). NCI's infection page uses 100.5°F. Use the lower figure, 100.4°F. A tenth of a degree is not worth debating while you feel unwell.

Also important: NCI says to talk with your doctor or nurse before taking any medicine for a fever, even aspirin, acetaminophen, or ibuprofen. MedlinePlus says the same about fever reducers. Taking one first can hide a sign of a serious problem.

CDC says to tell the person checking you in that you are a cancer patient on chemotherapy. If you have a fever, you might have an infection. That is life-threatening, and you should be seen quickly. MedlinePlus suggests wearing a mask around other people, especially in waiting rooms.

MedlinePlus lists these measures:

• Wash hands often with soap and water.
• Practice safe food and drink handling.
• Take care around pets and animals.
• Avoid people with symptoms of infection.
• Avoid travel and crowded public places.

MedlinePlus and ACS also suggest wearing a mask when you have to be around people, and ACS says to avoid large crowds. Infection and neutropenia covers the practical detail.

If your team has prescribed a growth factor, ask them how and when to take it. See the linked growth factor page for background.

Everything above comes down to one skill: knowing when to pick up the phone. MedlinePlus lists the symptoms that should prompt contact, and several are easy to dismiss:

• Fever, chills, or sweats.
• Diarrhea that will not stop, or that contains blood.
• Severe nausea and vomiting, or being unable to eat or drink.
• Extreme weakness.
• Redness, swelling, or discharge at an intravenous line or port site.
• A new rash or blisters.
• Abdominal pain.
• A very bad headache, or one that will not go away.
• A cough that is getting worse.
• Breathlessness at rest or during simple tasks.
• Burning when passing urine.
• Confusion, dizziness, or chest pain (ACS).

Chills with shaking, even without a recorded temperature, is reason enough to call.

R-CHOP day by day shows how these low-count windows map onto one common treatment schedule.

The list above is what to phone about. This is how to sort it by speed.

• Call 911 or go to an emergency department if a fever comes with confusion, clammy or sweaty skin, a racing or weak pulse, breathlessness, or extreme pain or discomfort. CDC lists those as signs of sepsis, and calls sepsis a life-threatening emergency. A low neutrophil count is what turns an ordinary infection into that. Do not drive yourself.
• Call 911 or go to an emergency department if you are shaking uncontrollably with chills, you feel faint or cannot stay upright, you have chest pain, or you have trouble breathing even at rest. ACS lists those as reasons to get help immediately. Do not drive yourself.
• Call your care team straight away, day or night, if you have a temperature of 100.4°F (38°C) or higher, with nothing else wrong. That alone is enough. Do not take acetaminophen or ibuprofen first to see if it settles. NCI warns those medicines can hide a more serious problem.
• Call your care team right away if you have any of the other signs listed above: a line site that is sore or leaking, a headache that will not go away, burning when passing urine, a worsening cough, unstoppable diarrhea, a new rash, or you cannot eat or drink. MedlinePlus says to call right away for signs of infection.
• Call your care team right away if you missed a growth factor shot, so they can tell you what to do.

• https://medlineplus.gov/ency/patientinstructions/000675.htm
• https://medlineplus.gov/ency/patientinstructions/000913.htm
• https://www.cancer.gov/about-cancer/treatment/side-effects/infection
• https://www.cdc.gov/sepsis/about/index.html
• https://www.cdc.gov/cancer-preventing-infections/patients/fever.html
• https://www.cancer.org/cancer/managing-cancer/side-effects/low-blood-counts/neutropenia.html