A leachable cyclic amide (caprolactam) can be found in normal saline (NS) and 5% dextrose in water (D5W) plastic bags widely used in clinical practice if they contain polyamide in a multilayer sheeting. This contamination and the parameters that could influence its content have never been studied in a public work such as a scientific publication. Two independent laboratories validated a caprolactam dosing method and studied contamination levels in several containers. Caprolactam content in multilayer polypropylene/polyamide/polypropylene plastic bags ranged from a mean (SD) of 5.43 (0.21) mg/L (D5W 1,000 mL) to 22.83 (1.26) mg/L (NS 50 mL). NS and D5W can be intravenously administered with a total daily dose of 3 L, corresponding to a minimal daily dose of 16.3 mg of caprolactam. The high levels of contamination we have reported and the possibility of administering caprolactam to high-risk patients (eg, neonates, the elderly) should make it imperative for pharmaceutical companies to communicate publicly on the safety of caprolactam.