Former UFC fighter Ketlen Vieira’s difficult period continues even after her move to the PFL. First, she missed her chance to claim the belt against MMA great Cris Cyborg at PFL Tampa in August after missing the featherweight championship limit by 7.2 pounds. Then, she lost the fight by unanimous decision. Now, things have taken a turn for the worse, with the Brazilian failing the doping tests conducted following her fight that night. As such, Vieira has been handed a six-month suspension from the sport.

According to an exclusive report from Sherdog, Mike Mazzulli, director of the Mohegan Tribe Department of Athletic Regulation, which oversees the PFL’s anti-doping program, confirmed that Vieira tested positive for an undisclosed “steroidal substance” prohibited by the World Anti-Doping Agency (WADA).

Mazzulli did not specify which substance was detected in the Brazilian’s sample. However, he did confirm that both her A and B samples collected after her Cris Cyborg fight returned adverse findings for the prohibited substance.

As a result, Ketlen Vieira’s six-month suspension will begin retroactively from August 22, 2026, which was the date of her fight against Cyborg.

Vieira (16-6) has since addressed the suspension in an interview with MMA Fighting, attributing the positive test to medication she took to treat a longstanding knee injury. According to the former UFC fighter, the treatment took place after her release from the UFC in May and before she signed with the PFL in June.

“The thing is, throughout my time in the UFC, my team and I were always extremely careful with supplements and medical treatments to ensure there was never any risk of a test detecting a prohibited substance,” Vieira said. “In 10 years with the organization, there was never a single incident.

“However, after leaving the UFC and becoming a free agent, I had the opportunity to take a more comprehensive approach to my health and undergo medical treatment for a knee injury that I had been monitoring for a long time but that never fully healed due to the various medication restrictions I had to follow while competing in the UFC. So, my team and I took advantage of the fact that I had no active contract and focused heavily on treating my knee. I was able to take the necessary medications to help ensure the best possible recovery.”

Going by Vieira’s statement, she and her team believed that after being let go by the UFC in May, they could finally focus on treating her knee without the medication restrictions she had faced while competing in the MMA promotion. She maintains that the positive test was not the result of a deliberate attempt to use performance-enhancing substances.

The Brazilian went through two notable knee injuries during her ten-year run in the UFC, both of which affected her preparation for scheduled fights.

In August 2018, Viera had to withdraw from her scheduled bout against Tonya Evinger because of a knee injury that required surgery. More than five years later, she injured her knee again ahead of her January 2024 fight against Macy Chiasson.

The 35-year-old revealed that the second injury occurred after one of her training partners landed a shot during practice, resulting in a meniscus injury and a fibula fracture. That time, however, the Amazonas native avoided surgery and recovered after three months of physical therapy.

With her knee still requiring attention, the featherweight believed she finally had an opportunity to address the problem properly. However, she did not expect the PFL to sign her while she was undergoing treatment. The unexpected offer ultimately changed her plans, and she believed the medication would have cleared her system before her fight against Cyborg.

“What none of us expected, however, was to be surprised by the great news that I had been signed by the PFL,” Viera added. “As soon as we learned about the opportunity, we immediately discontinued all medications, but continued with non-medication treatments. To be completely honest, I believed that given the time between stopping the medications and my fight, there would be no possibility of any substance showing up in my tests.

“However, after the fight, we were informed that this had occurred. Despite what happened, we thank God that the knee treatment has produced good results. Since there was no intent to violate any rules on our part, the PFL decided to give me a six-month period to ensure everything is in order before my next fight.”

Ketlen Vieira’s account suggests that she believed stopping the medication before the fight would prevent any prohibited substance from appearing in her test. However, it didn’t go that way.

Now the adverse findings in both samples have resulted in the suspension, regardless of her stated intentions.

It’s worth noting, though, that the Brazilian had maintained a clean record during her UFC tenure. Prior to the latest violation, the UFC had reportedly tested her seven times between 2025 and 2026 without a positive result.

This again suggests the doping violation could be, as she said, unintentional.

Regardless, Ketlen Vieira will be eligible to return to competition after her suspension ends on March 22, 2027. Nevertheless, the six-month ban has already drawn a reaction from her last opponent, Cyborg, who thanked the PFL’s anti-doping program for taking swift action.

Cris Cyborg reacts to Ketlen Vieira’s doping violation

When it comes to doping violations, Cris Cyborg has experienced her own share of controversy. In 2011, the Brazilian MMA legend tested positive for stanozolol metabolites following her victory over Hiroko Yamanaka in a Strikeforce featherweight championship bout.

Cyborg attributed her violation to a dietary supplement. However, the California State Athletic Commission overturned her victory to a no-contest, suspended her for one year, and imposed a $2,500 fine. Strikeforce subsequently stripped her of the featherweight title, marking one of the most controversial moments of her career.

After Vieira’s positive test became public, Cyborg reflected on her own experience with doping and thanked Mike Mazzulli and the athletic commission for taking drug testing seriously. She also shared words of encouragement and respect for her former opponent in a lengthy Instagram post.

“I want to take a moment to thank Mike Mazzulli and the athletic commission for taking drug testing seriously and holding fighters to a high standard,” Cyborg wrote in a lengthy Instagram post. “My career has not been perfect, and I have never tried to hide from my past. In 2011, I had a positive test for a banned substance, served my suspension, accepted responsibility for what was in my body, and made major changes to the way I managed my team and supplements.

“Since then, I have competed under some of the most rigorous testing programs in MMA, including testing overseen by Mike Mazzulli, and I have continued to pass those tests. That is why I believe strict, independent testing is important. It protects the fighters, the sport, and the legacy we work our entire lives to build. I also want to give respect to Ketlen Vieira. She is a tough competitor, a fellow Brazilian and a former UFC title challenger.”

For Ketlen Vieira, the immediate priority will be ensuring that her treatment and recovery remain on track before she returns to competition. Her six-month suspension gives her a timeline to work toward, but her next appearance will come after a difficult stretch that has included a missed championship opportunity, a loss to Cris Cyborg, and now a failed doping test. The PFL’s decision also shows that its anti-doping rules apply to established fighters.