HGH is not illegal, but it is banned in many professional sports, including in the NFL since 2011.
That's the same year that, according to the documentary by Al Jazeera America, the star quarterback used the performance-enhancing drug to aid his recovery from multiple surgeries.
Manning is not alone in denying the allegation of HGH use -- the doctor and even the source who made the claim to Al Jazeera called the report false.
Allegations from clinic employee
Al Jazeera's report, "The Dark Side
," claims the network's explosive report is based in part on conversations captured on hidden camera.
Dr. Dale Guyer is the owner of the Guyer Institute, an anti-aging clinic in Indianapolis.
Former Guyer Institute employee Charlie Sly alleges Manning and other athletes were provided with HGH from the clinic by mail. Sly claimed the packages were sent to Manning -- then a player for the Indianapolis Colts -- under his wife's name, Ashley Manning.
In the documentary, Sly tells Al Jazeera about the drugs Guyer allegedly would provide his clients.
"Like growth hormone, all the time, everywhere..." Sly said in the report. "And it would never be under Peyton's name, it would always be under her name."
"The statements on any recordings or communications that Al Jazeera plans to air are absolutely false and incorrect," Sly said.
In an interview with MSNBC on Monday, Al Jazeera reporter Deborah Davies stood by her work
, saying that the network spent six days recording Sly.
"Let's be clear what the allegation is and what it's not," Davies said. "What Charlie Sly says is that the Guyer Institute shipped human growth hormone to Ashley Manning in Florida. I have not heard anyone deny that."
In the interview with ESPN, Manning said his wife's medical needs and prescriptions were her own private business.
Colts: Report is 'utterly ridiculous'
The Colts, the Broncos and Guyer all released statements Sunday denying the allegations in the story and supporting Manning.
"The allegation that I would do something like that is complete garbage and is totally made up. It never happened. Never," Manning said in a statement released by the Broncos. "I really can't believe somebody would put something like this on air. Whoever said this is making stuff up."
His former team, the Colts, said: "We've been made aware of the recent Al Jazeera report concerning Peyton Manning and find it utterly ridiculous. We are thoroughly familiar with Peyton's tireless work habits, his medical history, and, most importantly, his integrity."
Guyer, for his part, denied that Sly had ever been an employee, but only an unpaid intern who worked in his office for three months.
Tom Brady: 'I fully support Peyton'
Tom Brady also voiced his support for Manning, calling the Broncos quarterback "a guy that I can always count on." On Monday, in his weekly appearance on WEEI's "Dennis & Callahan" show, the New England Patriots quarterback shared his thoughts about the news surrounding Manning.
"Peyton, I would consider him a good friend," Brady said. "You hate to see your good friends go through anything like that. He's been a great player for this league, for his teams, for his organizations. He's been one of the best players to ever play the game. Nobody has more respect for Peyton than I do, and everything that he's accomplished. There's always challenging times, but he's a tough guy. I know that. He's a very mentally and physically tough guy."
Brady is no stranger to controversy, considering the ongoing Deflategate saga
during the last year. But despite Brady's own circumstances, he offered no advice for Manning.
"He's a big boy," Brady said. "He knows how to handle these things."