DOI: https://doi.org/10.36347/sjmcr.2026.v14i11.007

Pages: 2430-2431

Filgrastim, a recombinant granulocyte-colony stimulating factor (G-CSF), is commonly used to prevent and treat chemotherapy-induced neutropenia. Hypersensitivity reactions to filgrastim are rare and typically immediate; however, delayed allergic responses after multiple administrations have been occasionally reported. We present a case of a 50-year-old female with localized triple-negative breast cancer who developed an acute hypersensitivity reaction following the sixth filgrastim injection. The reaction included diffuse erythematous rash, dyspnea, chest tightness, and tachycardia, which resolved rapidly after discontinuation of filgrastim and symptomatic treatment. This case highlights the importance of ongoing clinical vigilance during GCSF therapy and the need for systematic pharmacovigilance reporting to enhance patient safety.