Patients with allergies or intolerances and those requiring special diets are among the groups that require formulations with special excipients. When compounding preparations for this population, the suitability of dyes, flavorings, sweeteners, preservatives, gelatins, milk products, gluten, corn, soy, nuts, alcohol, chocolate, and other animal-derived ingredients must be considered. Unlike manufacturers of foods and nutritional supplements, pharmaceutical companies are not required to list certain ingredients of manufactured drugs, such as wheat. Therefore, a patient may unknowingly purchase a manufactured drug containing an excipient that he cannont tolerate. Once informed of a patient's allergy, intolerance, or special diet, the compounding pharmacist is able to prepare a prescription from which a particular excipient has been eliminated. In many cases, however, the particulars of a patient's specific allergy or intolerance are difficult to determine and predict, and thus creative thinking is required from the copounding pharmacist. Without question, the need for special excipients will continue.