What dosage of biotin is good for 26 female 105lbs?

30 mcg usually: Adequate amounts of biotin are provided by the bacteria in your gut normally. Supplementation is rarely necessary. There is no significant body of data that shows that extra biotin supplementation works except possibly in some diabetics. Supplements can cause hideous constipation in some too (Trust me on this one). See http://www.med.nyu.edu/content?ChunkIID=21571