Coffee Brown and Joe Alcock discuss the perils and pitfalls of too much oxygen. We discuss the recent IOTA study - a metaanalysis done by Paul Young's team and the upcoming ICUROX trial. This evidence is going to change how we practice medicine. It also has insights for evolutionary biology - our bodies can be self destructive, as in heart attacks and strokes, but healing processes may rely on normal to low normal oxygen levels. Too much oxygen may indeed be a bad thing