A 75-year-old man who had previously received complementary intravesical treatment with MMC and BCG. After tumour recurrence, he started treatment with intravesical gemcitabine. During the first instillation, the patient presented intense local burning, dizziness and profuse sweating (grade 2)5, which made it necessary to stop treatment. Although hypotension (90/60 mmHg) occurred post instillation, blood pressure normalised (130/80 mmHg) within a few minutes with postural measures. Dysuria improved over the next 24 hours with oral anti-inflammatory treatment. Urine culture was negative. Treatment was discontinued by patient's decision. After two weeks he started intravesical treatment with MMC with good tolerance after four instillations.