PRP (Platelet-Rich Plasma) injections can be beneficial for both patches of lost/thinning hair and global hair loss, but the effectiveness depends on the underlying cause and severity of hair loss. Localized Thinning/Patches (e.g., traction alopecia, small areas of androgenetic alopecia): PRP can help stimulate regrowth in these targeted areas by increasing blood flow, reducing inflammation, and activating dormant follicles. Global Hair Loss (e.g., diffuse androgenetic alopecia, telogen effluvium): PRP can improve hair density and thickness overall, but results may vary. It is typically most effective when combined with other treatments like topical solutions, scalp treatments, and/or light therapies. PRP works best for early-stage hair loss when hair follicles are still viable. If someone has significant bald areas where follicles are already lost, PRP alone may not be enough, and hair transplants might be needed. Best of luck, I hope this helps! Genie Alexander, RN BSN for Anna Petropoulos, MD FRCS at Center for Classic Beauty, Boston & Danvers MA.