Which combination of symptoms are characteristic of phenytoin toxicity?

• A. ataxia, nystagmus, slurred speech, decreased mentation
• B. tachycardia, hypertension, palpitations
• C. fever, rash, joint pain
• D. headache only

Answer: (A)

Phenytoin toxicity primarily causes central nervous system depression that affects coordination and mentation. The most characteristic cluster is ataxia, nystagmus, slurred speech, and decreased level of consciousness. Nystagmus is often the earliest sign; as levels rise, coordination worsens, speech becomes more slurred, and mentation declines. The other options don’t fit this CNS-toxicity pattern: cardiovascular symptoms aren’t typical of phenytoin overdose, fever with rash and joint pain suggests a hypersensitivity reaction, and a headache alone is nonspecific and not distinctive of phenytoin toxicity. If toxicity is suspected, confirm with a phenytoin level and follow the charted management plan to adjust dosing and monitor neurologic status.