A 40-year-old woman was admitted to the intensive care unit after a radical resection of a recurrent abdominal malignancy. Her postoperative course was complicated by sepsis requiring numerous abdominal operations with the abdomen being left open for drainage and dressings. Use of povidone-iodine soaked abdominal packs to reduce secondary infection led to development of thyrotoxicosis, which resolved following the cessation of the iodine dressings. A high index of suspicion is needed for the diagnosis of this condition in intensive care patients as the usual haemodynamic signs of thyrotoxicosis may be misinterpreted as being caused by sepsis.