Which antibacterial drug increases the risk of developing serotonin syndrome?

• A. Vancomycin
• B. Linezolid
• C. Chloramphenicol
• D. A and B

Answer: (B)

Linezolid carries MAOI-like activity, which can raise serotonin levels in the brain. When this antibiotic is used with other serotonergic medicines—such as SSRIs, SNRIs, TCAs, meperidine, tramadol, triptans, or fentanyl—the risk of serotonin syndrome increases because serotonin isn’t broken down as quickly. Vancomycin and chloramphenicol don’t affect serotonin metabolism, so they don’t add this risk. That’s why linezolid is the best answer. Be mindful of potential symptoms like agitation, confusion, rapid heart rate, high blood pressure, and muscle rigidity if these drugs are used together, and consider alternatives or adjust concurrent serotonergic medications.