At what dosage should the nurse carefully monitor a client taking phenelzine?

Phenelzine, a monoamine oxidase inhibitor (MAOI), requires careful monitoring due to its side effects, particularly at certain dosages. Dizziness is a notable effect that can occur with the use of phenelzine, especially as its dosage increases or when a patient is starting treatment. This can be attributed to several factors, including changes in blood pressure and alterations in neurotransmitter levels that affect central nervous system functioning.

Patients on phenelzine may experience orthostatic hypotension leading to dizziness, especially when moving from a sitting or lying position to standing. Therefore, vigilant observation for symptoms such as lightheadedness or unsteadiness is critical, especially when dosage adjustments are made. Monitoring for dizziness aids in the prevention of potential falls and ensures the medication is being tolerated appropriately.

The other options, while they can occur, are less directly associated with the dosage-related monitoring that is crucial during treatment with phenelzine. Increased secretions, facial flushing, and diarrhea can occur but are not as consistently problematic across dosages as dizziness tends to be, particularly in the context of blood pressure changes.