Which of the following is NOT a symptom of phenytoin overdose?

• A. Nystagmus
• B. Ataxia
• C. Rash
• D. Diplopia

Answer: (C)

Phenytoin overdose mainly causes signs of central nervous system depression and cerebellar dysfunction. You’ll see neurological symptoms such as nystagmus (involuntary eye movements), ataxia (poor coordination), and diplopia (double vision) because excess phenytoin disrupts CNS pathways involved in movement and gaze. These are classic overdose findings and reflect the drug’s CNS depressant effect.

Rash, on the other hand, is not a typical feature of acute phenytoin overdose. Skin reactions can occur with phenytoin as a separate adverse effect or hypersensitivity reaction (like Stevens–Johnson syndrome or other drug eruptions) and may require stopping the drug and urgent evaluation. So, rash isn’t part of the overdose syndrome, even though it can be related to phenytoin exposure in other contexts.