Biotin users generally see thicker, fuller hair within two to three weeks of use. Biotin helps to boost keratin structure in the human body. The strengthened keratin structure gives added strength to hair in the shaft leading to less hair loss and longer hair.
Biotin is not proven to actually cause hair to grow longer. However, it does cause hair to become stronger at the shaft, reducing hair loss in the process. Many people use this complex B vitamin daily in oral form to help lessen hair loss and breakage. The stronger the hair, the better the chances of it growing longer.