YOU SAID:
「"I can state with certainty that this medicine is not very effective."」
INTO JAPANESE
「この薬はあまり効かないと断言できます。」
BACK INTO ENGLISH
"I can safely say that this medicine doesn't work very well."
INTO JAPANESE
「この薬はあまり効かないと言っても過言ではない。」
BACK INTO ENGLISH
"It's no exaggeration to say that this drug doesn't work very well."
INTO JAPANESE
「この薬はあまり効かないと言っても過言ではない。」
BACK INTO ENGLISH
"It's no exaggeration to say that this drug doesn't work very well."
You've done this before, haven't you.