WebMD Feature Archive How Hidden Health Concerns Wear You Out continued... Your meds are knocking you out. Statins, cholesterol-lowering drugs that can deplete body levels of CoQ10, a coenzyme vital to producing energy in cells. Often, switching to a different statin solves the problem. The most common are allergy or nighttime cold remedies, which contain diphenhydramine HCL, a sedating antihistamine. If an OTC label lists fatigue as a side effect, ask the pharmacist for suggestions on nonsedating meds. If you're overweight and/or have a family history of diabetes, ask your doctor for a fasting blood glucose test to measure your levels. If caught early, diabetes can be controlled with simple lifestyle changes such as increasing exercise, lowering fat intake, and losing excess pounds. "Less than 25 percent of my female patients get enough exercise to feel energized," says Ann Kulze, M.D., author of Dr. Ann's 10 Step Diet.