Hair loss is caused by genes, hormones (DHT), age (number of hair cycles) and stress. A hair transplant is a stress. In my career, my group has performed over 17,000 surgeries over 31 years so I have seen the impact of a surgery when a man has miniaturized hairs (they lose these miniaturized hairs with a surgery) unless they are on finasteride. This is a fairly reliable assessment of the situation and that is one reason I am never excited about performing any hair transplant procedure on someone under the age of 25 when miniaturization, which precedes balding, is commonplace. So, if I performed a hair transplant just on the receding corners of a 21 year old male, I would witness hair loss that could decimate this young man well beyond what I came to ‘fix’. We call this Shock loss and it is very common in men in their 20s who get a hair transplant, even a small hair transplant.