SummaryBackgroundCompensatory hyperhidrosis due to the treatment for focal primary hyperhidrosis can be devastating and life‐altering.ObjectiveThe purpose of this paper is to discuss use of the iodine starch test and dilute botulinum toxin to decrease compensatory hyperhidrosis over large surface areas.MethodsA large area of the trunk affected by compensatory hyperhidrosis was treated with dilute botulinum toxin therapy using a starch iodine test for localization.ResultsThe patient had exceptional results with his compensatory truncal sweating returning to normal and remaining stable for multiple months.ConclusionTreating compensatory hyperhidrosis of large surface areas with dilute botulinum toxin therapy is effective and safe.