Errani had competed at the Roland Garros final in 2012 where she lost to Maria Sharapova and reached her highest ever world ranking of five the following year which was a huge rise for a player who had only just entered the top 100.
It was banned because of World Anti-Doping Agency concerns it was being abused by bodybuilders.
Though an independent tribunal set up by the International Tennis Federation has accepted Errani's explanation, she has still been handed a suspension as the Federation felt that she could have done more to prevent this happening, but the maximum punishment of a two-year ban for an accidental violation of this type was considered excessive. "There is no evidence I have intentionally violated the anti-doping rules; there is no evidence that Letrozole would enhance the performance of a female tennis player".
It ruled there was only a light degree of fault and consequently a two-month suspension commencing on August 3 was imposed, while Errani's results and prize money from February 16 to June 7 - the date of her next test, which was negative - have been disqualified.
Former would number five Sara Errani has been banned for two months after testing positive for a banned substance.
According to The Times, Errani was staying at her mother's house when she failed the test.More news: Eight people injured as van rams into diners, driver arrested
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The drug was present in her household because Errani's mother has been fighting breast cancer since 2005, and the substance Letrzole is in Errani's mother's breast cancer medication, Femara.
The tribunal sanctioned Errani, 30, after ruling that she could have done more to protect herself.
Commenting on the decision via a lengthy statement posted on her official Twitter account, Errani wrote: "I never took, in my life and during my career, any prohibited substance. The only hypothesis is food contamination".
The written reasons for the verdict revealed Errani had been visiting her mother prior to the date of her positive test on February 16.
"She [Fulvia] explained how in the past she had accidentally dropped pills from the blister pack from which Femara (letrozole) was discharged by hand on to the worktop or on to the floor", the tribunal's decision read.