This paper reviews the effects that drugs may have on the gingival and periodontal tissues. Drug-induced gingival overgrowth has been recognised for over 70 years but is becoming a more prevalent occurrence with wider use of antihypertensive and immunosuppressant drugs. The anti-inflammatory steroids, non-steroidal drugs and anti-TNF-α agents might all be expected to exert a dampening effect on chronic periodontitis although the evidence is somewhat equivocal and none of these drugs has emerged as potentially valuable adjuncts to treat periodontal disease. Desquamative gingivitis is a clinical appearance of aggressive gingival inflammation with which a number of drugs have been associated and the oral contraceptives have also been implicated in the development of gingival inflammation. Patients who are prescribed bisphosphonates and anti-platelet drugs are at risk of serious side effects following more invasive dental procedures including extractions and surgical treatments although timely, conventional management of periodontal disease may be undertaken to reduce periodontal inflammation, prevent disease progression and ultimately the need for extractions.