Rookie reliever Andrew McKirahan is set to return to the Braves on July 20 after serving his 80-game suspension for testing positive for performance-enhancing drugs.

He last pitched in the bigs in Toronto on April 19 — the day he learned of his suspension and spoiled his teammates’ celebration after a 5-2 win.

“It was something obviously that was difficult to do,” McKirahan, 25, said Wednesday. “But it was something I felt I had to do as a man and a professional baseball player. To tell the truth, to lay it all out there and let (the team) know that I made a mistake and move forward.”

The suspension, which the commissioner’s office levied April 20, stemmed from a drug test McKirahan took while he was with the Marlins in spring training. He said Wednesday he didn’t knowingly take the banned substance, Ipamorelin.

“I was in spring training, and I was going through a little dead arm, and I used a cream that I shouldn’t have used, obviously,” he said. “It happened to have a peptide in it that they test for. It was a careless mistake of mine and something that I learned from. So, it wasn’t like I went out there and shot myself up with steroids or anything else and tried to get an extra leg up. It was a careless mistake and something that I’ll definitely learn from and pay a lot more attention to.”

McKirahan currently plays for Triple-A Gwinnett. Players are granted 16 days of minor-league rehab assignment during their suspension. He’s pitched twice since arriving July 4, allowing no runs on three hits and striking one over two innings.

Before landing in Gwinnett, he threw simulated games for the Braves’ Gulf Coast League affiliate in Orlando, Fla., where he said he stayed sharp against the younger hitters and learned to relax more on the mound.

But it’s nice to prep for a big-league return against guys who didn’t recently graduate high school.

“It’s obviously different (in Gwinnett), being in a game environment,” McKirahan said. “You have a lot of experienced hitters, so I think the next couple weeks will really help me to be ready to join up with the big-league team.”

The Braves claimed McKirahan off waivers from the Marlins on April 1 after he spent four years in the Cubs’ farm system, missing parts of 2012-13 with Tommy John surgery.

He pitched in three games this season before the suspension, allowing two runs on three hits while striking out two over 4 1/3 innings. The Braves needed a lefty arm to ease Luis Avilan’s workload, and McKirahan was making a solid case for the job.

Then the commissioner’s office called.

“(A suspension) really humbles you as a person,” McKirahan said. “When you’re doing something that you love and you make it to the highest level for the first time, and then two weeks later it’s all taken away. You really come down to earth, and yeah, it puts everything in perspective. You realize how lucky you are to be there and you do everything you can to not take it for granted.”

The Braves still haven’t found that other lefty, forcing Avilan into a league-high 44 games. Manny Banuelos, who likely will go to the bullpen when Williams Perez is healthy, could be the solution. But adding McKirahan’s arm to the mix doesn’t hurt.

McKirahan was a Rule 5 draft selection in December, so he must stay on a major-league roster the entire season. Or, if the Braves don’t want him, they must offer him back to the Cubs for half his original $50,000 claiming price.