Platelet rich plasma or PRP is very effective in all race or sex. However, some people has better response than others. Individual may see some results after only one treatment but it is highly recommended to get multiple PRP treatments. Results also depends on the quality of PRP. Some hair clinics may be using poor quality of PRP and that may not produce good results but if a higher quality of PRP with proper activation is used than results are very good. First response after getting the PRP hair treatment is decrease hair loss than people start to see hair growth. If someone is looking for much better results than they could add ACell or AmnioFix which could be combined with PRP.
The hair follicle will respond the same to PRP and skin color does not matter in that respect. I would recommend you try it.
