Wasps forward Ashley Johnson will be available for the start of the Premiership season despite receiving a six-month ban for failing a drugs test.
The 32-year-old convinced an independent panel that he mistakenly consumed his wife's dietary supplement before failing the test on 7 February.
His ban has been backdated to February, despite Johnson playing four times for Wasps since then.
Hydrochlorothiazide was found in his urine in an out-of-competition test.
South African Johnson said: "I was horrified when I got the test results and once we tracked back and worked out I had inadvertently taken the wrong tablet.
"I completely accept that I am responsible for everything in my body."
The Rugby Football Union's lawyers wanted the suspension to be imposed from 16 March, when Johnson was informed of his provisional suspension.
That would have seen Johnson miss three further league matches, with Wasps opening their 2018-19 campaign at Worcester Warriors on 1 September.
He will now be free to resume playing from 7 August.
A statement from Wasps read: "At a hearing conducted by the independent national anti-doping panel, [Johnson] advised he mistakenly took his wife's fat burner 'the Secret' rather than his own legitimate supplement 'Nutrilean'.
"Under World Rugby regulations, Johnson is permitted to fully resume training with his club with immediate effect."
Johnson was 'careless' - RFU's Watkins
Wasps Director of rugby David Young said: "This situation has highlighted just how easily a player can make a mistake of this kind.
"We have therefore strongly reinforced to all our squad that they must always be on their guard and fully aware of exactly what they consume."
Johnson added: "Drug use is not something I would ever condone, and from now on I will be extra vigilant at all times."
The fat burner product was tested by both the player and the RFU for hydrochlorothiazide - which was not listed in the product's ingredients - and on both occasions it returned a positive result, an RFU statement said.
Stephen Watkins, RFU anti-doping and illicit drugs programme manager, added: "[Johnson] was careless in his failure to acknowledge his responsibilities as a rugby player and ensure he was dutiful in checking what he consumed.
"The risk of contamination in supplements is significant to all players and therefore we advise that there is no guarantee that a supplement is free from prohibited substances."