The Manchester City defender is suspended from all forms of the game until a hearing into his case is held by the Football Association. Toure is facing the possibility of anything up to a two-year ban unless he can come up with some mitigation for testing positive for a 'specified substance', which the 29-year-old believes came from a stimulant contained in one of his wife's slimming tablets.
Wenger said: "He is devastated but legally, what is forbidden is forbidden. The mistake he made is not to have asked the Manchester City doctor whether he could take it or not."
He added: "It was completely the kind of stupid thing that can happen when you're punished in life.
"Cross the road, don't look right or left and boom. Half the people don't ask if you deserve it, if you're caught, you're caught.
"He wants to control his weight a little bit because that is where he has some problems and he took a product belonging to his wife. I don't think there's a desire there to do something wrong and hide it. He was not cautious enough."
A devout Muslim and one of the cornerstones of City's continued push into the Manchester community, Toure seemed the least likely player to get embroiled in such a situation.
However, a player's public profile may not be enough to save him according to Michele Verroken, founding director of Sporting Integrity and formerly UK Sport's Director of Drug-Free Sport.
"There are enough warnings out there," she said. "It is a risk for any professional athlete to take any supplements without speaking to their club's medical staff first.
"If what is being said by Mr Wenger is correct, then it is what we call a fat burner, which increases the heart rate. You simply cannot afford to be taking this stuff. There is no excuse."