Q. A 49-year-old man comes to the outpatient clinic to discuss his recent lipid profile, which showed a decrease in high-density lipoprotein (HDL), and a moderate increase in both low-density lipoprotein (LDL) and triglycerides. The patient's medical history is significant for allergic rhinitis. He never smokes; however, drinks alcohol socially. The physician prescribes niacin for dyslipidemia. The above patient should be counseled regarding which of the following potential side effects?