British sprinter Bernice Wilson has failed in her appeal against a four-year suspension handed out after a positive drugs test in June 2011.
The 27-year-old, who tested positive for two anabolic steroids, broke into the British team last year, competing at the European Indoor Championships.
Wilson blamed a contaminated sample for her positive test.
UK Anti-Doping chief Andy Parkinson said: "This sends a strong message to anyone looking to dope in the UK."
Lincolnshire sprinter Wilson tested positive for banned steroids testosterone and clenbuterol after running the 100m in 11.95 seconds at the Bedford International Games on 12 June.
She issued a statement in July calling for UK Anti-Doping, who administer drug testing in the UK, to withdraw the case and open an internal investigation to determine the cause of the contamination.
However, an independent National Anti-Doping Panel upheld the European Indoor 60m semi-finalist's four-year ban.
"We have successfully argued for a four-year ban which demonstrates that UK Anti-Doping always seeks robust sanctions against athletes who look to cheat the system and betray those around them," Parkinson added.
"[It] gives clean athletes the confidence that we are working hard on their behalf, within the framework of the World Anti-Doping Code, to protect their right to compete in doping-free sport."
Spanish cyclist Alberto Contador tested positive for Clenbuterol during the 2010 Tour de France, which he claimed was a result of eating contaminated beef.
Clenbuterol, similar to the asthma drug salbutamol, is used to treat breathing disorders as a decongestant and bronchodilator. It causes an increase in aerobic capacity, blood pressure and oxygen transportation, and speeds the rate at which fats are burned.
It is officially classified as a sympathomimetic steroid.