Muscle cramps may be caused by fluid and salt loss induced by diffuse or focal hyperhidrosis. Recent reports have described the efficacy of botulinum toxin in the treatment of primary focal hyperhidrosis. Botulinum toxin inhibits sweating by blocking exocytosis of acetylcholine from presynaptic cholinergic nerve terminals. We report the case of a patient who complained of frequent muscle cramps associated with unusually severe axillary hyperhidrosis. We used botulinum toxin to treat the excessive focal sweating presuming that it would also reduce the muscle cramps. A total dose of 200 MU of botulinum A toxin (Dysport) per axilla markedly reduced sweating and cramps. The beneficial effect started four days after the injection and it was still present five months later Treatment was repeated in the sixth month with analogous results. No side-effects were observed and no compensatory sweating occurred
