Disulfiram and calcium carbimide are widely used alcohol deterrents. Their safe use, however, requires a knowledge of their pharmacology, toxicity, and interactions with alcohol and other drugs. The absorption, metabolism, and elimination of these compounds are described, as is the mechanism of their reaction with ethanol. The effects and limitations of the interaction between ethanol and disulfiram and calcium carbimide are discussed. Four areas of concern regarding toxicity are discussed, including medical complications of the reactions with alcohol, toxicity associated with repeated doses of disulfiram or calcium carbimide, possible interactions with other drugs, and acetaldehyde-induced hepatotoxicity and cardiotoxicity.