Baclofen, a commonly prescribed muscle relaxant, is primarily excreted via the kidneys; toxicity is a potentially serious adverse outcome in patients with decreased kidney function. We describe a patient with end-stage kidney disease receiving hemodialysis who developed neurotoxicity and hemodynamic instability after receiving baclofen for muscle spasms. In this case, prompt recognition of baclofen toxicity and urgent hemodialysis were effective in reversing this toxicity. This case is used to examine the pharmacokinetics and pathophysiology of baclofen toxicity and discuss appropriate diagnosis and management of baclofen toxicity. We recommend reducing the baclofen dose in patients who have moderately reduced kidney function (estimated glomerular filtration rate, 30-60mL/min/1.73m2) and avoiding use in patients with severely reduced kidney function (estimated glomerular filtration rate < 30mL/min/1.73m2) or on renal replacement therapy.