We report the case of a 16-year-old boy who was admitted to our hospital for acute urinary retention, flaccid paralysis of the legs and arms and rhabdomyolysis due to a nasal spray containing 9-alpha-fluoroprednisolone. In our normotensive subject, rhabdomyolysis occurred after vigorous physical activity performed before the administration. The case emphasizes the need to avoid the use of 9-alpha-fluoroprednisolone considering its intense mineralocorticoid activity.