Yorkshire Carnegie back row Brandon Staples has been banned for four years by the Rugby Football Union (RFU) following an anti-doping violation.
South Africa-born Staples, 20, tested positive for three steroids -- Dehydrochloromethyl-Testosterone, Metandienone and Stanozolol -- in August last year.
He claimed the adverse finding was the result of consuming a whey protein shake while on holiday in South Africa seven weeks previously.
However, that defence, and a subsequent appeal, was dismissed. Staples' ban has been backdated to Sept. 7, 2017 -- the date of his provisional suspension -- meaning he will be ineligible until Sept. 6, 2021.
"This is the first failed test for a performance enhancing substance in English professional rugby since 2011 and a reminder to all that we cannot be complacent in our efforts to keep rugby a clean sport," Stephen Watkins, RFU Anti-Doping and Illicit Drugs Programme Manager said.
"Education and deterrence remain core pillars to our anti-doping strategy and we must ensure we continue to educate players of the risks involved in supplementation. Ultimately individuals are responsible for what they put into their bodies and this case highlights what can happen if a player is not vigilant."