The rare syndrome of episodic hyperhidrosis with hypothermia is thought to be due to an abnormality in the hypothalamus. A patient with this syndrome had relief of his extreme sweating when prescribed the anticholinergic oxybutynin for unrelated urinary urgency.
Recently, the International Hyperhidrosis Society and two of its physician leaders conducted an in-depth webinar all about the use of oral medications, including oxybutynin, to treat a variety of types of hyperhidrosis. You can "watch the full video here." During this program, experts discussed oxybutynin as being one of the two most commonly used oral medications for hyperhidrosis, even in small children.