An endotoxin-like reaction is a host response to an agent that induces the release of endogenous pyrogens, including cytokines. The typical reaction that is associated with gentamicin is fever and chills, rigor, shivering, tachycardia with hypertension or hypotension, respiratory symptoms and muscle cramps. We report a case of a 92-year-old patient who developed an endotoxin-like reaction in the post-operative recovery unit following 200 mg of gentamicin. The reported side effect is not included in the drug sheet or in the British National Formulary. No similar incidents were reported in the UK. We discuss the clinical picture of this rare event, along with a review of the literature and recommendations.