Neutropenia (low neutrophil count)

Updated: 2025-01-23

Definition

Neutropenia (noo-troe-PEE-nee-uh) means that the body has too few neutrophils, a type of white blood cells. All white blood cells help the body fight infections. But neutrophils are important for fighting certain infections, especially those caused by bacteria.

If you have neutropenia, you likely won't know it based on any symptoms. People often find out that they have neutropenia when they've had blood tests done for other reasons.

A single blood test showing low levels of neutrophils doesn't mean you have neutropenia for sure. These levels can vary from day to day. So if a blood test shows that you have low levels, the test needs to be repeated. The repeated test may confirm whether you have neutropenia.

Neutropenia can raise your risk of infections. When neutrophil levels are very low, even the common bacteria from the mouth and digestive tract can cause serious illness.

Causes

Various health conditions and treatments can cause neutropenia. Depending on the cause, neutropenia happens because neutrophils are destroyed, made in fewer numbers or stored in an irregular way.

Causes of neutropenia include the following:

Cancer and cancer treatments

Certain cancers can cause neutropenia. These include:

• Leukemia
• Lymphoma
• Multiple myeloma

Various cancer treatments also can cause neutropenia. For instance, chemotherapy and radiation can destroy neutrophils and other healthy cells along with cancer cells.

• Bone marrow transplant
• Chemotherapy
• Radiation therapy
• Targeted therapy.

Medicines

• Medicines to treat overactive thyroid such as methimazole and propylthiouracil.
• Antibiotics such as nafcillin, penicillin G and oxacillin.
• Antiviral medicines such as acyclovir (Sitavig, Zovirax), ganciclovir (Ganzyk-RTU, Valcyte, others) and oseltamivir (Tamiflu).
• Anti-inflammatory medicines for conditions such as ulcerative colitis or rheumatoid arthritis. These include sulfasalazine (Azulfidine), leflunomide (Arava) and methotrexate (Rasuvo, Trexall, others).
• Antipsychotic medicines such as clozapine (Clozaril, Versacloz) and chlorpromazine.
• Medicines to treat irregular heart rhythms, including quinidine and procainamide.
• Medicines to treat some skin conditions, including dapsone (Aczone) and isotretinoin (Absorica, Amnesteem, others).
• A veterinary drug called levamisole that's not approved for human use in the United States but may be mixed in with cocaine.

Infections

• Chickenpox
• Coronavirus disease 2019 (COVID-19)
• Cytomegalovirus (CMV) infection
• Epstein-Barr virus
• Hepatitis A
• Hepatitis B
• Hepatitis C
• HIV/AIDS
• Measles
• Rubella
• Salmonella infection
• Sepsis (an overwhelming bloodstream infection)

Autoimmune diseases

• Granulomatosis with polyangiitis
• Lupus
• Rheumatoid arthritis

Bone marrow disorders

• Aplastic anemia
• Myelodysplastic syndromes
• Myelofibrosis

Other causes

• Genetic conditions such as Fanconi anemia, Kostmann syndrome and Shwachman-Diamond syndrome.
• Unknown reasons called chronic idiopathic neutropenia.
• Low levels of nutrients such as vitamin B-12, copper or folate.
• Some conditions of the spleen.

People can have neutropenia without a higher risk of infection. This is known as benign neutropenia.

When to see a doctor

Neutropenia doesn't cause obvious symptoms. So it alone likely won't prompt you to get a healthcare checkup. Most often, blood tests that are done for other reasons find neutropenia.

Talk with your healthcare professional about what your test results mean. You'll need more than one blood test to confirm that you have neutropenia. You also may need more tests to find out what's causing your neutropenia. A finding of neutropenia combined with the results from other tests might pinpoint the cause.

If you have neutropenia or take medicines that can cause neutropenia, call your healthcare professional right away if you notice symptoms of an infection. Infection symptoms can include:

• Fever above 100.4 degrees Fahrenheit (38 degrees Celsius).
• Chills and sweats.
• A new cough or a cough that becomes worse.
• Shortness of breath.
• A stuffy nose.
• A sore throat or a new mouth sore.

Some other possible symptoms of an infection are:

• Burning or pain with urination.
• A stiff neck.
• Diarrhea or vomiting.
• A change in skin color or swelling around any area where skin is broken or cut.
• Unusual vaginal discharge.
• New pain, including in the stomach area or rectum.

If you have neutropenia, you can take steps to lower your risk of infections. These safety measures include the following:

• Stay up to date on vaccinations, such as those for the flu and COVID-19.
• Wash your hands often.
• Wear a face mask in crowded places or around people who are sick.
• Try not to have close contact with people who are sick.
• Cook meat and eggs thoroughly to kill any germs.
• Wash raw fruits and vegetables well.
• Don't share food, drink cups, utensils or toothbrushes.