How much biotin should you take for hair growth? 2-5 milligrams
How long does it take biotin to work on 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.
What are the side effects of biotin? No side effects have been reported for biotin in amounts up to 10 milligrams a day. However, check with your health care professional if you notice any unusual effects while you are taking it.