Many commonly prescribed medications are capable of causing adverse oral drug reactions. The oral manifestations of drug therapy are often nonspecific and variable in significance. However, these undesirable effects can mimic many disease processes, such as pemphigus, erythema multiforme, lupus erythematosus, and lichen planus. They may also be very characteristic of a particular drug reaction. This article will first briefly describe the common presentations of oral drug reactions. The drugs most commonly responsible for these reactions will then be discussed along with any specific treatment. Finally, general clinical management and therapies will be outlined.