A Pilot Study Exploring the Efficacy and Safety of Topical Oxybutynin 3% Gel for Primary Focal Hyperhidrosis in Adolescents and Young Adults

Inclusion Criteria: * Eligible subjects must be 12-25 years old and meet consensus criteria for primary focal hyperhidrosis: focal, visible, excessive sweating of at least 6 months duration without apparent cause with at least two of the following characteristics: 1) Bilateral and relatively symmetric, 2) Impairs daily activities, 3) Frequency of at least one episode per week, 4) Age of onset less than 25 years, 5) Positive family history, 6) Cessation of focal sweating during sleep. * Eligible subjects must have moderate to severe hyperhidrosis which correlates to a score of 3 or 4 on the HDSS. * Hyperhidrosis must affect the bilateral axilla; however, patients with concurrent focal hyperhidrosis affecting the palms, soles, face, or other area will not be excluded. * Subjects must be willing to comply with the study protocol. Exclusion Criteria: * Subjects with hyperhidrosis of less than 6 months duration or hyperhidrosis secondary to an underlying infectious, endocrine, or neurologic disorder. * Treatment with botulinum toxin injections to the axillae or other affected areas within the last 12 weeks OR treatment with other agents (oral anticholinergic medications, topical aluminum chloride) in the last 4 weeks. * Subjects with active skin inflammation or infection affecting the axilla * Subjects who report history of closed-angle glaucoma, urinary retention, decreased gastrointestinal motility, hiatal hernia, cardiac arrhythmia, coronary artery disease, congestive health failure, hyperthyroidism, myasthenia gravis, xerostomia, renal insufficiency, or hepatic impairment. * Subjects with hypertension defined as systolic blood pressure \> 140 or diastolic blood pressure \> 90 on more than 1 occasion separated by 1 week. * Subjects with the following: history of somnolence, confusion, hallucinations OR subjects taking other medications that may cause somnolence, confusion, hallucinations OR subjects with other medical conditions that may predispose them for somnolence, confusion, or hallucinations. * Subjects who have demonstrated hypersensitivity to the drug substance or other components of the product * Subjects taking drugs which inhibit Cytochrome P450 3A4 (CYP3A4) * Pregnant and/or nursing females * Any other disease that would interfere with the study or place them at undue risk or who are in any way unable to comply with study requirements.