Adenosine is frequently administered to convert the rhythm of patients with paroxysmal supraventricular tachycardia to sinus rhythm. Adverse reactions are common after its administration, but these have been short-lived because adenosine has a half-life of less than 10 seconds. This report describes a 54-year-old male patient with chronic obstructive pulmonary disease who presented with paroxysmal supraventricular tachycardia at 200 beats/min. A 12-mg bolus injection of adenosine aggravated mild bronchospasm and produced respiratory failure. The patient subsequently required ventilatory support for 9 days. The presence of bronchoconstriction should be considered as a possible contraindication to the administration of intravenous adenosine.