Niacin (a B-vitamin) is used to treat low levels of HDL-C and elevated triglycerides and LDL-C. Niacin can increase HDL-C levels by 30% (and often by an even higher percentage with long-term treatment) and is the most effective agent for increasing low HDL-C levels. Immediate-release niacin is most effective but must be taken three times a day to develop a tolerance to the vasodilatory side effects, commonly known as “flushing”. Slow-release niacin is better tolerated but less effective in increasing HDL-C.