This is my own experience with the supplement. I took 5000mcg of biotin for several months. In the first instance, I noticed that it made me urinate a lot more often than usual.After a while things went back to normal. I also noticed that during this time a small patch of new hairs that I did not even miss, was growing in at the front section of my scalp. However, when I increased the dosage of biotin to 8000mcg (because I was getting 3000mcg from my daily multivitamin) something strange happened. One morning when I tried to raise up my upper body to get up out of bed, I had a severe pain in my lower back that made it woefully difficult for me to even shuffle my way out of bed or even sit up. I surmised it may have been the biotin so I stopped taking it for a while and I was myself again. However, I decided to try it again since I was not quite convinced that this could have been the reason; furthermore, I had visited my GP (Doctor) and he said that the biotin could not have been responsible for a pain that appeared to be a muscle pain so I resumed with the same dosage of biotin (5000mcg and 3000mcg from multivitamin), for a while a thought I was living a de ja vu. The very same thing happened again and so I was convinced that the high dosage could have been responsible for this odd pain.
I am still taking biotin, but only through multivitamin.
