But while McGwire seemed to imply the performance-enhancing drugs didn't contribute to his record-setting home run totals, Harrison -- who reportedly admitted taking human growth hormone -- said the fact the PEDs helped overcome injuries provided an advantage.
"Yes, anything that makes you feel better I think is a benefit," Harrison said on "The Waddle & Silvy Show" on ESPN 1000. "If it's banned by Major League Baseball or the National Football League, you shouldn't use it.
"If it's something that increased and accelerated the healing process, then yes, it's something that you get a benefit from."
Harrison, who won two Super Bowls with the New England Patriots, was suspended for the first four games of the 2007 season.
"I think the toughest part about it was when you come out and say that you made a mistake, really the disappointment in yourself that you have," said Harrison, who is an NFL analyst for NBC. "Also the impact you had on others, especially kids, because so many kids looked up to me and kids really thought of me as being a role model.
"And to come out, yes it was a negative situation, but I think it served as a positive light to let kids know as famous as we are and we're on TV, and you think we are this icon, we make mistakes, we screw up."
Harrison, a native of Markham, Ill., said McGwire's admission was commendable.
"The simple fact that he came out and he said he made a mistake, and he felt terrible about it, I give the guy a lot of props and a lot of respect," Harrison said.
"It was tough initially, because you are embarrassed and you are disappointed and you feel shame in yourself for making that mistake, but at the same time people have to be willing to forgive you," Harrison continued. "You have to forgive yourself first and foremost, but other people will forgive you if they feel like that you've admitted to what you did was wrong and that you are willing to move forward."
Harrison offered some advice to McGwire.
"I think the message here is for Mark McGwire to go out there and for him to tell others, 'I made a mistake, don't do this, this is bad,'" Harrison said. "[It] really made me feel crappy, because I have kids, and to put something in your body and not truly know what it is, you're being very selfish.
"And to really hurt yourself, because you don't know what's going to happen, what's going to be that first effect 10, 15, 20, 30 years from now. And I think it's really selfish, and loving the game more than you love your family, more than you love yourself at that particular time, I just think it was very selfish of myself, very selfish of other guys who have done it regardless if you have done HGH or if it was some other banned substance, or it was steroids, it's still something that we are not one hundred percent familiar with. And it's something you shouldn't do, because you have family and loved ones that need you to be around."