Niacin Toxicity (Nicotinic Acid Toxicity) By Larry E Johnson, MD, PhD, University of Arkansas for Medical Sciences Reviewed / Revised Nov 2022 View Patient Education Niacin (nicotinic acid) in large amounts is sometimes used to lower low-density lipoprotein (LDL) cholesterol and triglyceride levels and to increase high-density lipoprotein (HDL) cholesterol levels.