A medicine is a product that is suitable for treatment or prevention of diseases, or a product that can be used in or given to humans to modify body functions or to make a medical diagnosis. A medicinal product is composed of one or more active ingredients and other substances (excipients) which make up the rest of the product. An active ingredient is the substance in a medicinal product that is biologically active and produces the effect. Before you take a medicine, there are certain things you should keep in mind. Read the label and package leaflet to make sure you are taking the medicine correctly.