I found this:
“Deer antler, which has the ability to continually regrow, has been used in traditional medicine for over a millennium because there’s an idea that the velvet from antlers and the rich blood beneath it increases human energy, muscle repair, and libido. The science, however, is lacking.”
“Overall the conclusion that we came to, based on the studies that we reviewed, was that there really is very little evidence that velvet antler is effective for any conditions for humans,” Massey University psychologist Andrew Gilbey, Ph.D., who co-authored a 2012 paper titled “Health benefits of deer and elk velvet antler supplements,” tells Inverse.
“Claims by manufacturers do not seem to be supported by high-quality evidence.”