I'm a 20 years old. My hair is good but it's falling out. Can I take 1 tablet of biotin 10,000 mcg per a day?

You can take any supplements you think may help.  Biotin is associated with hair health but it will likely not keep your hair from falling out if your hair loss is genetic.  

you can use biotin to help with your hair loss. However the genetic progression of your hair loss is inevitable and will eventually fall off. There are two FDA approved medications that you use to help with your hair loss as well Propecia and rogaine. To find out about more about the supplements and products visit my website.

Of course you can take Biotin, or any vitamin but nothing will stop your hair loss if you have genetic balding other than Propecia. Why waste your valuable time a loose more hair while you fool around with worthless medications that will not impact your hair loss. My job is to help people and stop hair loss, and that is what should be your job, so go see a good doctor and get the diagnosis made and the drug Propecia if that is what you need.