A method where the body is repeatedly exposed to small amounts of an allergy causing substance, an allergen , in order to reduce the allergic reaction. For instance, if a person with diabetes has a bad reaction to taking a full dose of beef insulin, the doctor gives the person a very small amount of the insulin at first. Over a period of time, larger doses are given until the person is taking the full dose. This is one way to help the body get used to the full dose and to avoid an allergic reaction.