What is a common side effect of many medications?

Dry skin is a common side effect of many medications due to alterations in moisture levels and skin barrier function. Certain medications, especially those that affect hormonal levels or hydration, can lead to decreased oil production and result in dry skin. This is particularly notable with antihistamines, diuretics, and some psychiatric medications that can influence hydration and moisture retention in the body.

In contrast, the other choices generally reflect desired outcomes or benefits rather than common side effects. While increased energy and enhanced focus might be effects of specific stimulant medications, they are not universal side effects across a wide range of medications. Similarly, increased alertness can be a positive result of certain treatments but does not align with the more frequent adverse reactions reported in patients, making dry skin a more representative and frequent side effect in pharmacological studies.