Does taking biotin 2500 mcg cause thin ur blood? I am taking gnc ultra nourish hair what are the side effect of this vitamins?? Plz help. .

Vitamins. Biotin does not thin blood. The major side effect of the gnc battery is taking rupees from your pocket for something that has not been proven to work and it can contain anything they want to put in it as their products are controlled by any agency.