In the field of pharmacy, compounding (performed in compounding pharmacies) is the preparation of a custom formulation of a medication to fit the unique need of a patient which cannot be met with commercially available products. This may be done for medical reasons, such as to be administered by a different route (ex: tablet to liquid), to avoid a non-active ingredient the patient is allergic to, or to provide an exact dose that isn't commercially available. Medically necessary compounding is referred to as "traditional" compounding. Compounding may also be done for optional reasons, such as preference of flavor or texture, or dietary restrictions.