Niacin is a vitamin available in both prescription form and as over-the-counter dietary supplements. It is best known for its ability to improve cholesterol levels. The product comes in capsule and tablet form and is taken once daily, once or twice daily, or several times a day (depending on the specific product). Potential side effects of niacin include flushing, nausea or vomiting, and diarrhea.
Niacin (brand names include Niacor®, Niaspan®, Slo-Niacin®, and several others) is another name for vitamin B3. Some niacin products are non-prescription supplements, while others are prescription medications.
The term "niacin" can have several different meanings. In the strictest sense, niacin refers to just one compound -- nicotinic acid. However, it can also be used generally to describe other related compounds, including nicotinamide (niacinamide) and inositol nicotinate (inositol hexaniacinate). These types of niacin are not interchangeable and may have different medicinal activities. For the purposes of this article, the term "niacin" will mean nicotinic acid (not the other forms), unless otherwise stated.
Niacin is most often used for high cholesterol, although it may provide other benefits as well.
Niacor and Slo-Niacin are both made by Upsher-Smith Laboratories, Inc. Niaspan is made by Abbott Laboratories. Generic niacin products are made by various manufacturers.