Which of the following is a side effect of most antipsychotic medications?

Weight gain is a commonly recognized side effect of many antipsychotic medications, particularly the atypical antipsychotics. These medications can cause metabolic changes that lead to increased appetite and changes in glucose metabolism, contributing to weight gain. This effect can pose significant health risks for patients, as it may lead to obesity, diabetes, and other cardiovascular issues. The mechanism behind this side effect often involves alterations in neurotransmitter activity that influence hunger and metabolism.

The other options, while they may occur in specific contexts or with certain drugs, are not generally considered common side effects across the class of antipsychotic medications. Vision impairment, for example, can occur with certain medications but is not a common side effect found in the majority. Increased libido is not typically associated with antipsychotics; in fact, they often have the opposite effect on sexual function. Skin rashes may occur in some individuals due to allergic reactions or sensitivities, but again, this is not a widespread issue seen with most antipsychotic treatments. Thus, weight gain stands out as a significant and well-documented concern in the management of patients on these medications.