A manufacturer of a syringe product received complaints about discolored product that was nearing the end of shelf life. A root cause investigation was started and product syringes were put on stability. Headspace oxygen of syringe product samples with three different fill levels (Level 1=low, Level 2= medium, Level 3= high) was monitored over a period of 12 months. The initial levels of oxygen in the product samples were low. In the filling process, a nitrogen overlay was used to fill the headspace with nitrogen in order to protect the formulation from degradation by air. A laser-based headspace analysis proved to be a useful tool to check package integrity and for the presence of reactive headspace gases that can degrade the formulation.