People with hair thinning, in the following scenarios, meet criteria for PRP: Those who do not wish to start minoxidil (Rogaine) or hormone blocking medications (e.g. Propecia  or Spironolactone). Those who started minoxidil (Rogaine) or hormone blocking medications but stopped due to side effects. Those with hair thinning who had an improvement in their hair density with minoxidil (Rogaine) or hormone blocking medications and wish to try to achieve even further improvement ( This is the category that Dr. Craig Singer was in prior to receiving PRP). Those undergoing hair transplantation. Those with alopecia areata, traction alopecia or chronic telogen effluvium who did not respond to standard treatments.