London - Former Springbok Ashley Johnson said he was horrified to discover he had taken a banned substance, after receiving a six-month ban on Thursday.
The 32-year-old Wasps star - capped three times by the Springboks - had the ban backdated to February 7, making him eligible to play again from August 6, 2018, as the independent panel deemed he had not acted with intent.
The ban will therefore expire before the new European season starts.
Johnson, who can play at either hooker or in the back row and has been with Wasps since 2012, can resume training immediately.
"Johnson tested positive for the presence of a specified substance, hydrochlorothiazide (S5 Diuretics and Masking Agents), following an out-of-competition test at the Premiership club," read the panel's findings.
"The South African's urine sample returned an Adverse Analytical Finding (AAF) after being tested on 7 February 2018.
"The 32-year-old claimed the AAF was the result of mistakenly consuming his wife's dietary supplement - a fat burner called "The Secret" - which she purchased from South Africa.
"The 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.
"The independent panel accepted that the prohibited substance was not ingested intentionally."
Stephen Watkins, the Anti-Doping and Illicit Drugs Programme Manager for the Rugby Football Union (RFU), said Johnson should have been more responsible about finding out what the ingredients were in the product.
"Ashley Johnson was careless in his failure to acknowledge his responsibilities as a rugby player and ensure he was dutiful in checking what he consumed," he said.
"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."
Johnson, who signed a contract extension with Wasps last November, said this would make him be far more attentive in the future.
"I was horrified when I got the test results and once we tracked back and worked out I had inadvertently taken the wrong tablet," said Johnson.
"I completely accept that I am responsible for everything in my body. Drug use is not something I would ever condone, and from now on I will be extra vigilant at all times."