As an ingredient that has received significant attention and studies in the past, the safety and degree of effectiveness of Niacinamide has been well established to be on the safe side.
EWG: 1 (Low Hazard)
As of September 16, 2019, Niacinamide has achieved the lowest risk level possible from the Environmental Working Group, at score level 1. This ingredient has been reported in over 450 different products within the EWG database, with a number vastly larger to be more likely available in the general public. It has been quoted as not to be persistent or bioaccumulative according to the Environment Canada Domestic Substance List.
You can view EWG’s Niacinamide entry here.
US FDA: The US FDA has classified Niacinamide as ‘General Recognized As Safe (GRAS)’, meaning that it can be used in limited quantities and/or concentrations in nutrients and/or dietary supplements. As a dietary supplement, however, there are no strict regulations on its inclusion in skincare products and/or other applications. The continuing interest in Niacinamide and its effects on brightening skin has also afforded a number of studies to be conducted for efficacy and safety purposes.
Read more about the Efficacy of Niacinamide at the National Institutes of Health (NIH) Website
Read more about the Safety of Niacinamide at the National Institutes of Health (NIH) Website