The only reason I know for sure that I am on the real thing and not on a placebo is the fact that at about the 14th day of taking it, I decided to use a facial cleanser that I hadn't used for a long time. I didn't know it had alcohol in it, but I soon found out, as my face felt like it was going to burn up. I've retired that skin care regimen until I'm secure enough in my sobriety to get off the antabuse. I guess it is working after all, and even that small experience makes me sure I never want to know what would happen if I knowingly decide to ingest alcohol.