There are some examples where patient physiology can be responsible for poor yield of hair transplant results. However, this is a very rare occurrence and it is usually difficult to distinguish from human error.
According to various studies that have been worldwide conducted, when it is not a result of an external error, a hair transplant that is simply “rejected” by the body is usually caused by post-transplant Lichen Planopilaris (LPP).
LPP is an inflammatory scalp disorder that normally results in patchy alopecia.
Luckily, these percentages are low and theoretical in nature. This makes worrying about something like this occurring probably unnecessary. In the hands of an experienced hair transplant doctor and medical team, hair transplantation is a very safe and successful procedure. However more importantly, the probability of the body developing a condition and “rejecting” a hair transplant is extremely low.