Niacin, or vitamin B3, is an agent that results in the following physiologic changes: LDL reductions tend to occur in 5-7 days with the maximal effect seen in 3-5 weeks; triglycerides and VLDL are reduced by 20% to 40% in 1-4 days; and HDL levels can increase by 20%. This agent is indicated as adjunctive therapy in patients with elevated cholesterol and triglycerides when diet and other nondrug therapies are inadequate. The most common adverse effect of this agent is generalized flushing with a sensation of warmth, especially in the facial area. This reaction may be so severe in some patients that they discontinue therapy. Other common adverse effects include hepatotoxicity, tachycardia, hypoalbuminemia, hyperglycemia, nausea, vomiting, hyperuricemia, glucose intolerance, pruritus, peptic ulcer disease, and dry skin.