Abstract
Pegfilgrastim is a granulocyte colony-stimulating factor used in non-myeloid cancer patients to prevent infections and neutropenic fevers. Although this medication is widely used to induce granulocytosis in pancytopenia patients, there are certain instances where such a situation can cause severe side effects. In this case, we present a patient with a history of metastatic colon cancer who is currently taking pegfilgrastim to counter the agranulocytosis caused by his chemotherapy treatment. However, the patient shortly developed localized left-sided jaw swelling, and upon further investigation, the granulocyte colony-stimulating factor revealed an underlying bacteremia. A discussion will also be held regarding the mechanism of action of how pegfilgrastim induced this patient's symptoms as well as the risks and benefits.