I have scalp issues, and 5mg of biotin is usually prescribed by dermatologists for patients with hormonal alopecia, chemical damage or something 'lacking'. I think it's not as helpful for 'normal' people just looking for growth, because I have definitely seen a BIG difference. I heard lots of horror stories on here about people getting severe acne break outs, so started taking Biotin in small doses.
I started at 1mg for about a week, then moved up to 3mg for a week then moved up to 5mg.
When i got up to 5mg I started to get small complexion spots (bumps on the surface) and the odd zit, which is weird because I don't really get spots much anymore. However, they're not really that noticeable and went away when I started to drink more water.
I've been taking it for about 4 months, and while my skin looks more healthy and glow-y, it has taken me back to my teenage oily skin. As far as hair, it has definitely gave me some new growth and very soon after taking it I noticed my hair get darker/stronger from the roots.