The league announced the punishment after he tested positive for growth hormone-releasing peptide-2 (GHRP-2).
Collins released a statement to ESPN's Adrian Wojnarowski, saying he'll appeal the ban:
"First I want to apologize to my teammates, the Hawks organization, our fans, partners and community as a whole for this situation. 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."
Wojnarowski reported that Collins is working with the National Basketball Players Association to begin the process of appealing the suspension.
Collins is coming off a breakout 2018-19 season with the Hawks, who selected him with the 19th overall pick in the 2017 NBA draft. He averaged 19.5 points, 9.8 rebounds and 2.0 assists across 61 appearances during his second professional campaign.
The 22-year-old Wake Forest product was off to another strong start this season with 17.0 points, 8.8 rebounds and 2.0 blocks through five appearances.
His suspension will begin with Tuesday night's game against the San Antonio Spurs and, barring a successful appeal to reduce the time, run through the Hawks' Dec. 21 clash with the Brooklyn Nets. He'd be eligible to return Dec. 23 when they take on the Cleveland Cavaliers.
Jabari Parker and Alex Len will see a lion's share of the playing time in the Atlanta frontcourt while Collins is out. Bruno Fernando and Damian Jones should also get more minutes off the bench.