Linezolid-Induced Pancytopenia with Hyponatremia: A Case Report

BACKGROUND: Linezolid is an oxazolidinone antibiotic widely prescribed for actinomycetoma. Haematological adverse reactions, such as thrombocytopenia, have been widely reported due to linezolid. We report an unusual case of pancytopenia and hyponatremia secondary to injectable linezolid treatment for actinomycetoma. This case is peculiar as previous long-term exposure to oral linezolid one year back was uneventful. CASE REPORT: A 31-year-old male patient, a known case of actinomycetoma, presented to the dermatology outpatient department (OPD) with progressively worsening lesions for which injectable linezolid, meropenem, and sulfamethoxazole-trimethoprim combination were given. Patient developed pancytopenia with hyponatremia within 10 days of therapy initiation. Linezolid was stopped and replaced with doxycycline, whereas other drugs were continued. The test results were normalized within a week. Previous long-term exposure to similar oral therapy one year back did not cause any haematological or electrolyte abnormalities. CONCLUSION: Based on the World Health Organization-Uppsala Monitoring Centre (WHOUMC) causality assessment scale, the association between linezolid and pancytopenia with hyponatremia is considered probable in this case. This case report emphasizes that clinicians should be cautious, as these serious adverse effects can occur on re-exposure to linezolid, even if absent during previous use.