Prescription enzymes differ from over-the-counter products in that they offer much higher doses of enzymes that are standardized (precisely controlled) and regulated by the FDA.  If you have a condition called pancreatic insufficiency, in which the pancreas doesn't produce enough of the key digestive enzymes (lipase, protease, and amylase), a prescription enzyme regimen (known as pancreatic enzyme replacement therapy or PERT) is advised. Although some over-the-counter digestive enzymes offer the same enzymes found in the prescription formula, the dosage is significantly lower and typically insufficient for improving digestion.  Similarly, if your digestive symptoms stem from sucrose intolerance–a diagnosable condition known as sucrase isomaltase deficiency or CSID–enzymes bought at a store will not meet your needs. A digestive enzyme called sacrosidase (Sucraid) is available by prescription only. It comes in a liquid form that needs to be refrigerated and there is currently no over-the-counter substitute.