Which symptom should prompt reconsideration of ethambutol therapy?

• A. Optic neuritis
• B. Headache
• C. Rash
• D. Fatigue

Answer: (A)

Ethambutol can damage the optic nerves, so the symptom that should prompt reconsideration is changes in vision due to optic neuritis. This drug’s serious toxicity manifests as decreased visual acuity and impaired color vision (often red-green), which can be reversible if detected early by stopping or dose-adjusting the medication. Because vision changes directly reflect the known adverse effect on the optic nerves, they signal a need to reevaluate therapy.

Headache, rash, and fatigue are less specific and not the hallmark warning signs of ethambutol toxicity, so they don’t carry the same implication for rethinking the regimen. Regular vision monitoring is important when using ethambutol to catch these changes promptly.