Extensive Subcutaneous Hematoma in a Patient Receiving Nigella sativa Oil, Dual Antiplatelet Therapy, and Oxaliplatin-Based Chemotherapy: A Case Report.

BACKGROUND: Nigella sativa (black seed) oil is a commonly used herbal supplement. Here, we report the case of a patient enrolled in a clinical trial of N. sativa oil for chemotherapy-induced peripheral neuropathy (CIPN), who developed a large subcutaneous hematoma while receiving oxaliplatin-based chemotherapy in combination with dual antiplatelet therapy. CASE PRESENTATION: A 51-year-old man with colon cancer receiving FOLFOX plus cetuximab and dual antiplatelet therapy developed a large subcutaneous hematoma while participating in a clinical trial evaluating N. sativa oil for CIPN. After dose escalation to 2000 mg/day, progressive swelling and marked ecchymosis developed. Laboratory testing revealed clinically significant thrombocytopenia (platelet count: 52 × 103/µL). All suspected hemostasis-modifying agents were interrupted, and supportive management was initiated, resulting in complete resolution of the hematoma within 10 days. The patient was later re-exposed to a reduced dose (1000 mg/day) without recurrence of bleeding. The Naranjo Adverse Drug Reaction Probability Scale yielded a score of 4, indicating a possible adverse drug reaction. CONCLUSIONS: This case suggests a possible hemorrhagic complication in a patient with multiple concurrent bleeding risk factors, including dual antiplatelet therapy and chemotherapy-associated thrombocytopenia, in the setting of N. sativa oil exposure. It highlights the importance of systematically documenting herbal supplement use and proactively counseling patients about potential herb-drug interactions during cytotoxic chemotherapy. TRIAL REGISTRATION: Iranian Registry of Clinical Trials (IRCT), https://www.irct.ir, IRCT20090613002027N24.