What is the common side effect of the antipsychotic clozapine that requires monitoring?

Clozapine is an atypical antipsychotic that is particularly associated with the risk of agranulocytosis, a potentially serious decrease in white blood cell count. This side effect is significant because it can lead to an increased susceptibility to infections, which makes it crucial for patients on clozapine to be monitored regularly with blood tests to ensure their absolute neutrophil count (ANC) remains within a safe range.

The reason this side effect is particularly emphasized is due to its severity and the requirement for close monitoring. Regular monitoring, typically conducted weekly for the first six months and less frequently thereafter if counts stabilize, ensures that any drop in white blood cells can be addressed promptly, preventing complications.

While other options such as weight gain, diabetes, and dry mouth can also occur with clozapine, they are less critical in terms of immediate life-threatening risks compared to agranulocytosis. Therefore, the aspect of monitoring that clozapine necessitates relates specifically to the risk of agranulocytosis, making it the most pertinent concern when prescribing this medication.