Can a 14 year old take a biotin pill that is 10,000 mcg?

Hmmm....: Biotin deficiency is rare, but can occur in persons with genetic mutations, on long-term antibiotics or anti-convulsants, or who eat a lot of raw egg whites. There is no good evidence that this easily available, over-the-counter supplement is the magic potion to grow hair or prevent hair loss. Biotin is safe to take, but 10000 mcg per day is over 60 times the usual dose, so is not advisable.

Yes: I'm not sure it will help but while 10,000 mcg sounds like a lot it's equal to 10 mg,which doesn't seem so high. I have a patient who claims this dose improved hair growth but there's no research on this.There's no evidence of toxicity of high doses so safe to try.The main benefit of this dose is lower sugars in diabetics. Doses up to 300mg being researched in MS. See https://tinyurl.com/yas8kbou

Sure: It is unlikely to produce any benefit beyond what she would get from any other placebo.