Methenamine, in a gel stick formulation, effectively decreased palmar and plantar sweating in 24 of 26 individuals studied. All patients had essential hyperhidrosis and were evaluated in a doubleblind, placebo-controlled study. Even though methenamine is believed to act by the slow release of formaldehyde, one patient, who had a formaldehyde sensitivity that was proved by a patch test, was able to use the methenamine gel stick without difficulty. Approximately one third of the patients experienced some continuing relief for one to three weeks after discontinuing the trial medication. I conclude that methenamine is a safe, effective addition to the available types of topical therapy for essential hyperhidrosis.
Cullen SI. Topical Methenamine Therapy for Hyperhidrosis. Arch Dermatol. 1975;111(9):1158-1160. doi:10.1001/archderm.1975.01630210074008