Is flushing one of the side effects of b vitamin complex?

Effect of Niacin: Flushing is an effect of one specific b vitamin, a from of vitamin b3 called niacin; another form of b3, niacinamide, does not cause flushing. Most b vitamin complexes contain niacinamide an thus do not cause flushing. The main advantage of Niacin is that it lowers cholesterol better than niacinamide. The flushing is due to vasodilation so Niacin improves circulation.