Lipid injectable emulsions are an essential source of fatty acids, as well as a daily source of calories. They have been used in the clinical setting for almost 40 years, but despite this, there are no established official standards governing pharmaceutical quality. After 15 years of development, the United States Pharmacopeia (USP), which writes such standards for all FDA-approved pharmaceuticals, is poised to adopt an official monograph for lipid injectable emulsions that sets pharmaceutical requirements on all manufacturers placing limits on pH, free fatty acid concentrations and globule size (both mean droplet size and the population of large fat globules larger than 5 micrometers). Recent animal data has shown pathophysiologic changes in vital organs for lipids that fall outside the USP-proposed globule size limits. From a clinical perspective, newer lipid injectable emulsions show great promise in certain patient settings, most notably in the intensive care unit in both adults and infants. The clinical use of alternative oils, such as medium-chain triglycerides, fish oil and olive oil show benefits over conventional soybean oil formulations. In adults, for example, the administration of omega-fatty acids via soybean oil-based lipids produces a heightened inflammatory response via production of 2-series prostaglandins, whereas substitution of a portion of the lipid with omega-3 fatty acids via fish oil can favorably dampen the inflammatory response. In infants, for example, substitution of soybean oil with fish oil has recently been shown to reverse parenteral nutrition-associated liver disease. These advances should lead to safer infusion therapy in patients receiving lipid injectable emulsions.