How long does it take for biotin to regrow hair? It takes months to see results on biotin. According to The Journal of Clinical and Aesthetic Dermatology (source), biotin takes around 90 days to begin to work. Contrary to some of the claims you may have heard, biotin is not an overnight remedy that will magically give you 5 inches of hair growth in 24 hours.
How much biotin should you take for hair growth? Recommended dosage The Food and Drug Administration (FDA) does not have a daily recommended dietary allowance for biotin. However, according to estimates, an intake of 30 micrograms (mcg) may be adequate. The average intake of biotin in Western countries, excluding the United States, is an estimated 35–70 mcg per day.