The NBA announced Collins, who is in his third season with the Hawks, was handed a 25-game suspension after testing positive for growth hormone-releasing Peptide-2 (GHRP-2).
"First I want to apologize to my teammates, the Hawks organization, our fans, partners and community as a whole for this situation," Collins said in a statement. "I understand the impact this matter has on what we are trying to achieve together this season, and I am incredibly frustrated and disappointed in myself for putting all of us in this position.
"I have always been incredibly careful about what I put in my body, but I took a supplement, which, unbeknownst to me, had been contaminated with an illegal component. I plan to appeal my suspension in arbitration so I can get back on the court as soon as possible and continue to contribute to our 2019-20 campaign."
Collins is averaging 17 points in 32.2 minutes per game this season. He averages two blocks a game and leads the Hawks with 8.8 rebounds per game.
Collins became the third player in the league to receive a 25-game suspension for a drug violation this season. Phoenix Suns center Deandre Ayton was suspended after testing positive for a diuretic, and Brooklyn Nets forward Wilson Chandler was banned for testing positive for Ipamorelin.