The Prescription Strength allergy drops work by the principle of desensitization. When you place your Allergy Drops under your tongue a specialized cell called a dendritic cell “grabs” the antigens in the drop and presents them to your body’s immune system. Over time the immune system develops a tolerance to these substances. This process requires daily administration of the substance over a prolonged period of time. But, when used appropriately, the resulting decrease in allergy symptoms persists for years beyond the period of treatment.