Generally, drug induced reactions are more commonly seen in population. Certain drugs have the capacity to cause pathologic reactions in the oral and perioral region.Drug induced diseases can help the clinician to determine the relationship with a particular group of drugs. The underlying mechanism is unknown but the final outcome of the disease can be predicted by pharmacodynamics and/or pharmacokinetics. Xerostomia, Swelling, Dysguesia, Nonspecific Ulceration, Vesiculobullous or ulcerative mucositis, pigmentation of mucosa, Gingival enlargement, oral malodour, taste alterations, discoloration of teeth are the clinical presentation of drug induced reaction. This review article gives a brief description about the diseases caused by drugs, so that dentists can update their knowledge for a better diagnosis and treatment.