Finland's Robert Helenius has been hit with a two-year boxing ban by UK Anti-Doping (UKAD) on Friday after failing a drug test following his fight with Anthony Joshua.
Helenius tested positive for the banned substance clomifene after the heavyweight bout at London's O2 Arena in August last year.
The 40-year-old was knocked out by British fighter Joshua in the seventh round.
Helenius denied taking performance-enhancing drugs and, according to UKAD, said the detection of clomifene in his urine sample originated from the consumption of contaminated eggs and chicken.
However, a statement from UKAD read: "Following a request by UKAD, Mr Helenius was unable to provide any evidence that the eggs and chicken meat he had consumed in advance of the bout originated from hens that had been administered clomifene.
"Mr Helenius was therefore unable to identify the source of clomifene in his sample and therefore unable to reduce the applicable period of ineligibility of two years."
Female fertility drug clomifene can be used to boost testosterone levels in men and is banned by the World Anti-Doping Agency (Wada).
Helenius is entitled to credit for the time he has spent provisionally suspended since September, meaning his ban will end on September 17, 2025.
Nicknamed 'The Nordic Nightmare', Helenius had stepped in as a last-minute replacement for the fight after Joshua's original opponent Dillian Whyte tested positive for a banned substance.