Here's a bried synopsis of biotion from about.com:
Biotin
Type
Water Soluble
Forms / Names
Vitamin H and Coenzyme R
Functions
Coenzyme in energy metabolism, glycogen and fat synthesis
Deficiencies
Loss of appetite, nausea, depression, muscle pain, hair thinning, weakness, fatigue, rash, loss of hair, hallucinations
Toxicity
None known
Recommended Intakes
Estimated Safe and Adequate Intake:
30-100 µg/day for adults
30 µg/d for children ages 7-10 years
25 µg/d for children 4-6 years
20 µg/d for children 1-3 years
15 µg/d for children six months to 1 year
10 µg/d for infants birth to six months
Food Sources
Widespread in foods
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When you start using biotin, start of by using the smallest dosage because a number of people have a reaction from it. You can also take evening primrose oil, flaxseed oil, MSM, gelatin, natural vitamin E, and silica to aid in hair growth. But remember start off slow so you wouldn't have any adverse reation.