20.2 Botox for excessive sweating. Hyperhidrosis is a stressful 4 medical condition characterized by chronic excessive sweating. Primary hyperhidrosis is inherited and typically starts during adolescence. Botox (botulinum toxin) was approved for treatment of hyperhidrosis in adults in 2004. A clinical trial examined the effectiveness of Botox for excessive armpit sweating in teenagers aged 12 to 17 years. Participants received either a Botox injection or a placebo injection (a simple saline solution) and were examined four weeks later to see if their sweating had been reduced by 50% or more. Here are the study's findings:2 995 At least 50% reduction Treatment Yes No Total Botox 84 20 104 Placebo 44 64 108 Total 128 84 212 Give a 90% confidence interval for the difference (Botox minus placebo) in the proportions of teenagers with hyperhidrosis who experience at least 50% reduction in sweating. Follow the four-step process as illustrated in Examples 20 1 and 20.2