Treatment of focal hyperhidrosis with botulinum toxin type A: long-term follow-up in 61 patients

Background The blocking action of botulinum toxin type A (BTX-A) on cholinergically innervated sweat glands has been used successfully to treat patients with focal hyperhidrosis. Objectives To investigate the long-term efficacy and safety of intradermal injections of BTX-A. Methods We performed an open-label study in 61 patients treated over a period of 3 years for axillary or palmar hyperhidrosis. A total dose of 400 mU BTX-A (Dysport (R)) was injected into both axillae or 460 mU BTX-A (Dysport (R)) into both palms. The injections were repeated after relapse. Objective quantification of sweat production was performed using digitized ninhydrin-stained sheets. Results Four weeks after BTX-A treatment the median reduction in sweat production was 71% compared with baseline (P < 0.001) in the axillary group and 42% (P = 0.005) in the palmar group. Subjective assessment of sweat production by the patients using a visual analogue scale (0, no sweating; 100, the most severe sweating) showed a significant reduction in both the axillary (P < 0.001) and palmar groups (P < 0.001). Secondary disturbances due to focal hyperhidrosis interfering with daily activities were markedly improved in both groups. The median time interval between the sets of injections was 34 weeks for axillary hyperhidrosis and 25 weeks for palmar hyperhidrosis. The treatment of palmar hyperhidrosis was complicated by transient but not disabling weakness of the small hand muscles in nine of 21 patients. Conclusions Repeated intradermal injections of BTX-A in patients with axillary and palmar hyperhidrosis are as effective as first treatments.