Botulinum toxin can also be used to treat excessive sweating. In the same way that it blocks nerves from acting on muscles in the face, it blocks nerves from stimulating sweat glands. It involves approximately 15-20 injections into the armpit area with a tiny needle. It takes full effect within a few weeks and lasts around 6 months. The treatment takes about 15 minutes and is done in the clinic. Studies suggest that around eighty percent of patients have a 50% reduction in sweating following treatment.