Nicotinamide

Nicotinamide is a form of Vitamin B3. It's found in natural sources and in synthesized supplements. Unlike niacin, it does not cause flushing of the skin. It's available over the counter without a prescription. It's generally safe to use although high doses can cause damage to the liver. It's safe to use during pregnancy.
Nicotinamide is found naturally in yeast, meat, milk and green vegetables. 
Nicotinamide at Wikipedia