Causes

Numerous factors may cause neutropenia through destruction, decreased production or abnormal storage of neutrophils.

Cancer and cancer treatments

Cancer chemotherapy is a common cause of neutropenia. In addition to killing cancer cells, chemotherapy can also destroy neutrophils and other healthy cells.

• Leukemia
• Chemotherapy
• Radiation therapy

Drugs

• Medications used to treat overactive thyroid, such as methimazole (Tapazole) and propylthiouracil
• Certain antibiotics, including vancomycin (Vancocin), penicillin G and oxacillin
• Antiviral drugs, such as ganciclovir (Cytovene) and valganciclovir (Valcyte)
• Anti-inflammatory medication for conditions such as ulcerative colitis or rheumatoid arthritis, including sulfasalazine (Azulfidine)
• Some antipsychotic medications, such as clozapine (Clozaril, Fazaclo, others) and chlorpromazine
• Drugs used to treat irregular heart rhythms, including quinidine and procainamide
• Levamisole — a veterinary drug that's not approved for human use in the United States, but may be mixed in with cocaine

Infections

• Chickenpox
• Epstein-Barr
• Hepatitis A
• Hepatitis B
• Hepatitis C
• HIV/AIDS
• Measles
• Salmonella infection
• Sepsis (an overwhelming bloodstream infection)

Autoimmune diseases

• Granulomatosis with polyangiitis (formerly called Wegener's granulomatosis)
• Lupus
• Rheumatoid arthritis

Bone marrow disorders

• Aplastic anemia
• Myelodysplastic syndromes
• Myelofibrosis

Additional causes

• Conditions present at birth, such as Kostmann's syndrome (a disorder involving low production of neutrophils)
• Unknown reasons, called chronic idiopathic neutropenia
• Vitamin deficiencies
• Abnormalities of the spleen

People can have neutropenia without an increased risk of infection. This is known as benign neutropenia.