There are many factors that can influence nutritional intake. Food availability, physical capability, appetite, presence of gastrointestinal symptoms and perception of food are examples. Drug therapy can negatively influence nutritional intake through their effect on these factors, predominantly due to side effects. This review aims to give a brief overview of each of these factors and how drug therapy can affect them. Specific examples are given for each section and an indication of the impact on nutritional status. This article aims to assist the clinician in the identification of the effects of drug therapy on nutritional intake and provides advice on appropriate intervention. A drug history and side effect review should form an integral part of nutritional assessment. Early identification and effective therapeutic use of alternative drug therapy can also positively influence nutritional intake.