Supplementing 10 mg of biotin per day restores hair loss caused by biotin deficiency, according to Examine.com. As of 2015, there is no evidence showing that biotin restores hair loss in people without a biotin deficiency.
Biotin deficiency is caused by genetic deficiency of biotinidase, avidin consumption or as a side- effect of certain pharmaceuticals. Biotin deficiency causes hair loss, along with changes in nails and skin, as stated by Examine.com. Biotin is safe even when supplemented in high doses, and researchers don't know at what dosage biotin might start to pose health risks, as reported by WebMD. Biotin is a common ingredient in hair products.