Niacinamide is the amide form of nicotinic acid (Niacin). It is often used interchangeably with niacin. However it does not cause the flushing that niacin does. Caution must be exercised with niacin, niacinamide and sustained release niacin because larger doses may cause liver damage. The first indications of over-use are usually nausea and elevations of liver enzymes.