Chris Froome turned down the use of therapeutic use exemption (TUE) during his 2015 Tour de France success.
The Team Sky rider, and three-time tour winner, revealed that he rejected medical help in the last week of his second tour triumph.
Froome has admitted to receiving TUEs twice during his career.
The 31-year-old struggled in the final stages of the 2015 campaign, but clung on to win his second yellow jersey by one minute and twelve seconds.
As reported by the Mirror, Froome admitted that he struggled with an unspecified ailment but did not accept any assistance.
“I didn't feel having a TUE in the last week of the Tour was something I was prepared to do," said Froome.
"It did not sit well morally with me."
Cycling’s policy of using TUEs - where banned drugs are allowed to be used to treat medical conditions - came under scrutiny when Russian hackers published confidential details of athletes’ TUEs.
Froome used TUEs during a week’s oral course of the anti-inflammatory drug prednisolone to treat chest infections that aggravated his asthma in 2013 and 2014.
Former Team Sky teammate Sir Bradley Wiggins also suffers from asthma.
He was found to have three TUEs for the anti-inflammatory drug triamcinolone, taken on the eve of the 2011 and 2012 Tour de France and 2013 Giro D’Italia.
Wiggins became the first British rider to win the Tour de France in 2012.
Froome, Wiggins or Team Sky have not been accused of any wrongdoing or breaking any rules in all of the above cases.
However, Froome has said that the TUE system in cycling is “open to abuse”.
He believes that the World Anti-Doping Agency (Wada) needs to clamp down on their use.
“The fact that we're having that debate about authenticity means there's a problem with the system," he told the BBC.
"I think Wada need to tighten their regulations around TUEs, so they're not something that we question, their legitimacy.
"It's not good for sport in general. The fact that we're discussing the validity of results, that brings it back to the authorities, it is something they need to tighten up on so that there aren't questions being asked anymore."
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