can biotin upset the stomach?
<answer> Yes,Because of toxicity,It upset the stomach. <context> Along with vitamins B1, B2, B6, pantothenic acid (B5), and biotin, niacin works to release energy from the foods that we eat: protein ... Toxicity will not only cause stomach upset, but may also cause bleeding problems, flushed, itchy skin, and liver damage, a very serious side effect.