Which of the following is an example of an adverse drug reaction?

An adverse drug reaction refers to an undesirable and harmful effect resulting from taking a medication. In this context, experiencing a severe skin rash after taking a new medication exemplifies an adverse drug reaction because it is a negative response that may require medical attention. Adverse drug reactions can vary significantly in severity and can affect different parts of the body; in this case, the skin is experiencing a serious adverse effect.

The other options present scenarios that do not fit the definition of an adverse drug reaction. Feeling good after taking medication and improved health after medication usage both indicate positive outcomes, which are expected benefits of medications rather than harmful effects. On-time medication schedule adherence reflects proper medication management practices but does not pertain to the effects of the medication itself. Thus, the presence of a severe skin rash after taking medication is the clear and appropriate example of an adverse drug reaction.