Abstract: The subject invention provides methods for treating symptoms and/or conditions associated with idiopathic hyperhidrosis by using compounds that decrease the activity of serotonin 5-HT2C receptors. Compounds that can ameliorate symptoms of idiopathic hyperhidrosis and associated conditions include 5-HT2C receptor antagonists (i.e., ketanserin, ritanserin, mianserin, mesulergine, cyproheptadine, fluoxetine, mirtazapine, olanzapine, and ziprasidone) as well as 5-HT2C receptor modulators (i.e., inverse agonists, partial agonists, and allosteric modulators).