Vancomycin is a terror of a drug. The dosing is all weight-based (which is an outrage for us adult physicians who thought they had left paediatrics behind), but worse, drug level monitoring is both mandatory and confusing. And worst still, the old method of monitoring trough levels just got binned by half the world's pharmacologists in the last 3 years, in favour of more complex methods with exotic names like "trapezoidal equations" and "Bayesian models". Just what on earth is going on? Jeremy tries to explain everything, without causing anyone's aneurysms to pop.