Disulfiram

In Europe, where this drug is used more than in America, significant success rates have been documented from the long-term use of disulfiram (or antabuse).

Here is how it works:

When alcohol is consumed it is metabolized by the body into acetaldehyde, a very toxic substance that causes many hangover symptoms heavy drinkers experience. Usually, the body continues to oxidize acetaldehyde into acetic acid, which is harmless.

Antabuse interferes with this metabolic process, and hence a person taking antabuse  and then drinking with have 5 or 10 times more acetaldehyde than would normally be produced when they drink alcohol.  Like a super hangover from just one drink.

But there are also possibilities of more severe reactions including respiratory depression, cardiovascular collapse, myocardial infarction, acute congestive heart failure, unconsciousness, arrhythmias, convulsions, and death.