Iga Swiatek, the world No 2, has received a one-month ban after testing positive for the banned substance trimetazidine (TMZ) in August 2024.

In a statement on Thursday, the International Tennis Integrity Agency, which governs the tennis anti-doping programme, ruled that Swiatek’s anti-doping rule violation (ADRV) was not intentional and that she bore no significant fault or negligence for the positive test on “the lowest end of the range”.

The ITIA accepted that Swiatek’s positive doping test had been caused by her contaminated medication, melatonin, which she had taken for jet lag and sleep issues.

Swiatek wrote on Instagram: “I’m finally allowed … so I instantly want to share with you something that became the worst experience of my life.

“In the last 2.5 months I was subject to strict ITIA proceedings, which confirmed my innocence. The only positive doping test in my career, showing unbelievably low level of a banned substance I’ve never heard about before, put everything I’ve worked so hard for my entire life into question.

“Both me and my team had to deal with tremendous stress and anxiety. Now everything has been carefully explained, and with a clean slate I can go back to what I love most. I know I will be stronger than ever.

“I’m leaving with you a long video and right now I’m just relieved it’s over. I want to be open with you, even though I know I did nothing wrong.”

Swiatek had tested positive for TMZ in an out-of-competition urine sample taken on 12 August 2024 and she received a provisional suspension for three weeks between 12 September and 4 October. Swiatek withdrew from three tournaments during that period – the Korea Open, China Open and Wuhan Open – citing personal reasons.

After her three-week absence, Swiatek successfully appealed against her provisional suspension and she returned for the final two tournaments of the season, the WTA Finals and Billie Jean King Cup.

Over the past few years, Swiatek has established herself as the most successful tennis player of her generation. The 23-year-old Pole has won five grand slam titles, including four of the past five titles at Roland Garros, and she has been No 1 for 125 weeks, including for most of the 2024 season.

In a statement, the ITIA chief executive, Karen Moorhouse, said: “Once the source of the TMZ had been established, it became clear that this was a highly unusual instance of a contaminated product, which in Poland is a regulated medicine.

“However, the product does not have the same designation globally, and the fact that a product is a regulated medication in one country cannot of itself be sufficient to avoid any level of fault. Taking into account the nature of the medication, and all the circumstances, it does place that fault at the lowest end of the scale.

“This case is an important reminder for tennis players of the strict liability nature of the World Anti-Doping Code and the importance of players carefully considering the use of supplements and medications. It is vital that appropriate due diligence takes place to minimise the risk of inadvertent ADRVs such as this.”

The Women’s Tennis Association, meanwhile, acknowledged the findings of Swiatek’s anti-doping case and offered its support to Swiatek: “The WTA fully supports Iga during this difficult time. Iga has consistently demonstrated a strong commitment to fair play and upholding the principles of clean sport, and this unfortunate incident highlights the challenges athletes face in navigating the use of medications and supplements.

“The WTA remains steadfast in our support for a clean sport and the rigorous processes that protect the integrity of competition.”

Swiatek’s anti-doping case is the second high-profile case in tennis over the past four months after Jannik Sinner, the men’s No 1, received a ruling of no fault or negligence and no suspension in August after testing positive for the banned substance clostebol in March.

As with Sinner, the failed test and provisional suspension was not made public, and as with the Italian’s case some players have taken to social media stating that they believe those at the top of the game have greater resources that mean they are treated differently by authorities during the process.

However, the ITIA said of Swiatek: “As the player appealed the provisional suspension within 10 days of the notice and this appeal was successful, in line with the TADP (Tennis Anti-Doping Programme) rules, it was therefore not publicly disclosed.”