Does the PRP treatment works for areas that does not have any hair follicles?

It depends on your definition of no hair follicles or use of the word "bald".  If you are using the phrase "no hair follicles" to mean lack of terminal hairs, the answer is yes.  PRP can stimulate vellus hairs as stated below.  If there are no terminal or vellus hairs present, its unlikely (not impossible) that PRP will make any visible changes.  

This needs an in-person evaluation. I suggest seeing a hair loss expert now to evaluate and go over your condition and provide you information about your best treatment options. There are great non-invasive options like prp/progesterone and/or hair transplantation. See an expert. Best, Dr. Emer

PRP and the delivered growth factors are dependent upon the presence of viable follicles. It will not regenerate follicles de novo. Thus its benefits in areas with a history scarring alopecia are only seen in conjunction with grafting.
As always, discuss your concerns with a board certified plastic surgeon (ABPS), with experience in hair restoration.
Donovan Rosas MD
Board Certified by the American Board of Plastic Surgery
Member: American Society for Aesthetic Plastic Surgery, American Society of Plastic Surgeons
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