Hird reportedly believes the injections, administered around March last year, were legal amino acids and harmless.
He will meet Australian Sports Anti-Doping Authority (ASADA) investigators on Tuesday and tell them he took the injections because he was feeling sick, a source told News Limited.
Fairfax reports that the Australian Sports Anti-Doping Authority is trying to build "a case against Essendon over its use of anti-obesity drug AOD9604".
Meanwhile, AFL CEO Andrew Demetriou says he is "absolutely shocked" at the nature of substances allegedly given to Essendon players last season, describing the drugs crisis as "a terribly disturbing situation".
He said he was looking forward to hearing Hird's side of the story following explosive allegations the Bombers coach had injected a World Anti-Doping Agency-blacklisted drug.
Stephen Dank, the sports scientist that ran the Bombers' supplement program in 2012, has told Fairfax Media he injected Hird with the drug hexarelin, which was banned for players in 2004, and players were given an extract from pig's brains.
Coaches are not obliged to comply with the same rules as players when it comes to WADA-banned substances.
Essendon is conducting its own investigation, with the findings to be released in the coming weeks, while there is an ongoing investigation being undertaken by the Australian Sports Anti-Doping Authority and the Australian Crime Commission.
Hird said in a statement earlier on Thursday the accusations were "horrifying" and are "being made by a person or people who appear determined to destroy my reputation".
The Essendon coach also said he "can't wait" to tell his side of the story to ASADA and Demetriou echoed those comments, adding Hird was entitled to state his own case before any judgements were made.
"James Hird is one of the finest players to have ever played the game," he told reporters in Sydney.
"He's one of the finest contributors to the Essendon Football Club in its long and proud history and I'm sure he at the moment is feeling very, very disturbed by these allegations, as he suggested in his statement.
"He, like any individual, is entitled to have his say and put his case forward and we should, as a minimum, afford him that respect.
"I'm looking forward to hearing what he has to say to the ASADA investigators, which obviously will be conveyed back to the AFL.
"Notwithstanding that, it doesn't matter who you are in this game, the expectation of our supporters is that they watch sport in its purest form and that no person or no action that seeks to gain advantage by improper means will be tolerated in this code."
The first milk from a mother cow and a bark extract are other substances Dank said he had given players and Demetriou admitted he had been shocked to hear some of the allegations.
"Absolutely shocked," Demetriou said.
"I've heard of some of them and I continue to learn more about them and of course I'm shocked.
"I'm shocked by the complexity of the substances, the potential injurious nature of these substances, I'm horrified by a parent that, if true, young people are being injected with these substances.
"It's a terribly disturbing situation."
Hird's Essendon side is on top of the AFL ladder ahead of this week's trip to Perth to face Fremantle on Friday night.
Asked if Hird should be stood down following the latest allegations, Demetriou said the investigation must be allowed to run its course, adding, "We don't conclude investigations on the basis of newspaper reports".
The AFL has established a 'whistle-blower' service, which Demetriou said had already led to two people coming forward to provide information that was yet to be made public.
Demetriou said the AFL had quickly got on the front foot since the ACC and ASADA's announcements regarding drug use in sport, but he couldn't say what damage had already been done to the League.
"What I would say is everyone knows that the AFL has taken this matter seriously, we’ve responded immediately to the ACC report.
"We've put in some significant and enhanced measures that were approved by the AFL Commission – we've now banned the use of IVs, we've done an audit on supplements, we're establishing registers for all people involved in football clubs, we've established a whistle-blower service and we've gone beyond that.
"But I've also said that anyone who thinks they can run the gauntlet with the measures that we've put in place, and partake in any activity that is not in keeping with the spirit of the code and what is legally acceptable in our code, there's no place for them in our code."
James Dampney is a reporter for AFL.com.au. Follow him on Twitter: @AFL_JD
