Final answer:
The correct instruction for a client prescribed nicotinic acid is that the medication may cause flushing. This medication should not necessarily be taken on an empty stomach, nor does it eliminate the need for dietary changes or serve as a treatment for chest pain.
Step-by-step explanation:
For a client with hypercholesterolemia and atherosclerosis prescribed nicotinic acid (Niaspan), the nurse should provide the following instruction: "This medication may make you flush." Nicotinic acid is a form of niacin, which can cause flushing as a side-effect due to the dilation of blood vessels. It's important to inform patients about this so they are not alarmed when it occurs.
Taking nicotinic acid on an empty stomach may increase the likelihood of gastrointestinal discomfort, therefore it is usually not recommended. Conversely, dietary modifications are an essential part of managing hypercholesterolemia, and taking medications does not mean one can disregard dietary changes. Lastly, nicotinic acid is not indicated for relief of acute symptoms like chest pain; medications for chest pain, like nitroglycerin, work differently and are used under different circumstances.