Which of the following is a side effect associated specifically with MAOIs?

The identified side effect associated specifically with monoamine oxidase inhibitors (MAOIs) is muscle aches. MAOIs are a class of antidepressants that work by inhibiting the enzyme monoamine oxidase, which is involved in the breakdown of neurotransmitters such as serotonin, norepinephrine, and dopamine. While they can be effective in treating certain types of depression, MAOIs also come with a range of side effects.

Muscle aches can occur as a reaction to the pharmacological activity of MAOIs, particularly when coupled with dietary restrictions required to avoid tyramine, which can lead to hypertensive crises. This reaction often manifests as physical discomfort or pain and can be an indicator of medication interactions or sensitivity to the drug's effects on neurotransmitter balance.

Considering the other side effects discussed, orthostatic hypotension is a common side effect associated with various classes of antidepressants, not exclusively MAOIs. Loss of appetite is also seen with many medications within the antidepressant group. Increased perspiration can occur with several antidepressants as well, but is not a hallmark feature tied specifically to MAOIs.

Thus, muscle aches serve as a more specific side effect of MAOIs compared to the other options presented.