Can You Clarify Why There Is a Time Period it Takes for Propecia to Start?

Doctor Rassman, I appreciate your great blog. There is no more informative site on hair transplants. I am 51 yr old male with the following question on propecia:

Having gone through all of your archives, and other sites, I still am confused as to what exactly happens when one takes propecia that makes it necessary to weight six to eight months before we can tell if hair loss is being stopped. I know you use the terminology of anagen cycle but could you be more detailed and explain this a bit better. I have read web sites claiming hair loss stops in 4 months on propecia, but other doctors, like yourself and Dr. Bernstein suggest no benefits with regards to stopping hair loss until at least the 6th to 8th month. Could you clarify this, please. Knowledge is power.

Everyone responds differently to Propecia (finasteride). Some people get great results rapidly, while other go the ‘slow route’. Usually, the better results (quicker) are seen in the younger man or the man who has had recent hair loss, more so in the crown than the front. The 8 month recommendation is a ‘catch-all’ recommendation, knowing that the good studies on the drug show effectiveness between 8-12 months. The visual benefits require hair length and as the hair grows at about 1/2 inch a month, it takes time for the hair that grows under the influence of the Propecia to work its way up the ‘visual’ shaft. Much of what we report here are statistics that we have learned work well. Be patient and wait it out if you have just started taking the medication.