The nurse has completed a teaching with a client prescribed phenytoin daily for seizure activity. The nurse determines the session is successful after the client correctly chooses which potential adverse reaction that can occur if the client misses a dose of medication?

A. CNS depression: CNS depression is typically associated with phenytoin toxicity or drug interactions, not missed doses. Skipping phenytoin leads to subtherapeutic levels, which increase seizure risk rather than causing sedation or CNS suppression. B. Hypotension: While IV phenytoin can cause hypotension if administered too rapidly, oral phenytoin is unlikely to cause significant blood pressure changes. Missing a dose does not trigger hypotension as a common effect. C. Recurrence of seizures: Phenytoin maintains a stable therapeutic level to prevent seizures. Missing doses can drop blood levels below the therapeutic range, greatly increasing the risk of seizure recurrence or even status epilepticus in some clients. D. Nystagmus: Nystagmus is a dose-related side effect that can occur with phenytoin toxicity, not with missed doses. It signals high serum drug levels rather than low ones and is more likely when the client exceeds prescribed dosages.