Italy’s Sara Errani says she is “disgusted” her ban has been increased from two to 10 months after a cancer drug showed up in a failed test.
The former world number five, runner-up at the 2012 French Open, tested positive for banned drug letrozole.
The Court of Arbitration for Sport accepted medication taken by her mother found its way into a family meal.
But it said Errani, 31, was guilty of a “light degree of fault” which justified a 10-month ban.
She reacted by saying: “I am really disgusted by this matter. I don’t think anything similar has ever happened or been managed – in my humble opinion – in such a shameful manner.”
The decision followed appeals by the Italian anti-doping agency, which asked for a longer ban, and Errani, who wanted her voided results to be reinstated.
Errani, who reached the final four of last week’s Croatia Bol Open but withdrew before her semi-final match, must now serve another eight months of suspension.
The winner of five Grand Slam doubles titles, she was initially banned for two months by the International Tennis Federation (ITF) in August 2017 and her results from 16 February to 7 June that year were declared void.
Errani said her mother had been using the drug as part of her breast cancer treatment and had dropped some pills on a kitchen worktop where tortellini and broth were later prepared.
Letrozole increases lean body mass and was banned by the World Anti-Doping Agency (Wada) over concerns it was being abused by bodybuilders.
An independent tribunal, appointed by the ITF, said there was no evidence it would enhance the performance of an elite tennis player.