Which adverse effect of chloramphenicol significantly limits its clinical usefulness?

• A. Allergic reactions and anaphylaxis
• B. Bone marrow suppression
• C. Significant gastrointestinal manifestations
• D. Photosensitivity

Answer: (B)

Bone marrow suppression is the primary reason chloramphenicol’s use is so limited. It can cause a dose-dependent, reversible suppression of hematopoiesis, leading to anemia, leukopenia, and thrombocytopenia. More concerning is a rare idiosyncratic aplastic anemia, which can be fatal and is not predictable by dose. Because this severe, potentially irreversible bone marrow toxicity outweighs the benefits, chloramphenicol is reserved for serious infections when no suitable alternatives exist. Other adverse effects like allergic reactions, GI upset, or photosensitivity can occur, but they do not pose the same level of life‑threatening risk as hematologic toxicity.